Commit Graph

138 Commits

Author SHA1 Message Date
Kirill A. Shutemov
9f5bd30818 vgaarb: fix signal handling in vga_get()
There are few defects in vga_get() related to signal hadning:

  - we shouldn't check for pending signals for TASK_UNINTERRUPTIBLE
    case;

  - if we found pending signal we must remove ourself from wait queue
    and change task state back to running;

  - -ERESTARTSYS is more appropriate, I guess.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: stable@vger.kernel.org
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-12-11 14:04:44 +10:00
Al Viro
dfbf53ed54 vgaarb: remove bogus checks
neither ->release() nor ->poll() can be called unless ->open()
has succeeded on the same struct file, so checking for "has
open() failed" is pointless.  What's more, ->poll() doesn't
return -E... - it always returns a bitmap of POLL... values,
so the dead code in that one had been actively bogus.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-06 21:17:17 -05:00
Lukas Wunner
e02328f47b vga_switcheroo: Drop client power state VGA_SWITCHEROO_INIT
hda_intel.c:azx_probe() defers initialization of an audio controller
on the discrete GPU if the GPU is powered off. The power state of the
GPU is determined by calling vga_switcheroo_get_client_state().

vga_switcheroo_get_client_state() returns VGA_SWITCHEROO_INIT if
vga_switcheroo is not enabled, i.e. if no second GPU or no handler
has registered.

This can go wrong in the following scenario:
- Driver for the integrated GPU is not loaded.
- Driver for the discrete GPU registers with vga_switcheroo, uses driver
  power control to power down the GPU, handler cuts power to the GPU.
- Driver for the audio controller gets loaded after the GPU was powered
  down, calls vga_switcheroo_get_client_state() which returns
  VGA_SWITCHEROO_INIT instead of VGA_SWITCHEROO_OFF.
- Consequence: azx_probe() tries to initialize the audio controller even
  though the GPU is powered down.

The power state VGA_SWITCHEROO_INIT was introduced by c8e9cf7bb2
("vga_switcheroo: Add a helper function to get the client state").
It is not apparent what its benefit might be. The idea seems to
be to initialize the audio controller even if the power state is
VGA_SWITCHEROO_OFF (were vga_switcheroo enabled), but as shown
above this can fail.

Drop VGA_SWITCHEROO_INIT to solve this.

Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-11-05 11:07:36 +10:00
Lukas Wunner
5d170139eb vga_switcheroo: Constify vga_switcheroo_handler
vga_switcheroo_client_ops has always been declared const since its
introduction with 26ec685ff9 ("vga_switcheroo: Introduce struct
vga_switcheroo_client_ops").

Do so for vga_switcheroo_handler as well.

 drivers/gpu/drm/amd/amdgpu/amdgpu.ko:
   6 .rodata       00009888
- 19 .data         00001f00
+ 19 .data         00001ee0
 drivers/gpu/drm/nouveau/nouveau.ko:
   6 .rodata       000460b8
  17 .data         00018fe0
 drivers/gpu/drm/radeon/radeon.ko:
-  7 .rodata       00030944
+  7 .rodata       00030964
- 21 .data         0000d6a0
+ 21 .data         0000d678
 drivers/platform/x86/apple-gmux.ko:
-  7 .rodata       00000140
+  7 .rodata       00000160
- 11 .data         000000e0
+ 11 .data         000000b8

Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Darren Hart <dvhart@linux.intel.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Christian König <christian.koenig@amd.com>.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-10-20 20:19:29 +02:00
Lukas Wunner
fa3e967fff vga_switcheroo: Use enum vga_switcheroo_client_id instead of int
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-10-16 15:50:56 +02:00
Lukas Wunner
21c5ba8c1e vga_switcheroo: Use VGA_SWITCHEROO_UNKNOWN_ID instead of -1
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-10-16 15:50:56 +02:00
Lukas Wunner
203d027de4 vga_switcheroo: Use enum vga_switcheroo_state instead of int
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-10-16 15:50:55 +02:00
Lukas Wunner
8f12a3118f vga_switcheroo: Add missing locking
The following functions iterate over the client list, invoke client
callbacks or invoke handler callbacks without locking anything at all:

- Introduced by c8e9cf7bb2 ("vga_switcheroo: Add a helper function to
  get the client state"):
  vga_switcheroo_get_client_state()

- Introduced by 0d69704ae3 ("gpu/vga_switcheroo: add driver control
  power feature. (v3)"):
  vga_switcheroo_set_dynamic_switch()
  vga_switcheroo_runtime_suspend()
  vga_switcheroo_runtime_resume()
  vga_switcheroo_runtime_resume_hdmi_audio()

Refactor vga_switcheroo_runtime_resume_hdmi_audio() a bit to be able to
release vgasr_mutex immediately after iterating over the client list.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-10-02 10:21:13 +02:00
Rasmus Villemoes
945ef5bb14 vgaarb: use kzalloc in vga_arbiter_add_pci_device()
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-10-01 11:25:23 +02:00
Lukas Wunner
21b45676b7 vga_switcheroo: Set active attribute to false for audio clients
The active attribute in struct vga_switcheroo_client denotes whether
the outputs are currently switched to this client. The attribute is
only meaningful for vga clients. It is never used for audio clients.

The function vga_switcheroo_register_audio_client() misuses this
attribute to store whether the audio device is fully initialized.
Most likely there was a misunderstanding about the meaning of
"active" when this was added.

Comment from Takashi's review:

"Not really.  The full initialization of audio was meant that the audio
is active indeed.  Admittedly, though, the active flag for each audio
client doesn't play any role because the audio always follows the gfx
state changes, and the value passed there doesn't reflect the actual
state due to the later change.  So, I agree with the removal of the
flag itself -- or let the audio active flag following the
corresponding gfx flag.  The latter will make the proc output more
consistent while the former is certainly more reduction of code."

Set the active attribute to false for audio clients. Remove the
active parameter from vga_switcheroo_register_audio_client() and
its sole caller, hda_intel.c:register_vga_switcheroo().

vga_switcheroo_register_audio_client() was introduced by 3e9e63dbd3
("vga_switcheroo: Add the support for audio clients"). Its use in
hda_intel.c was introduced by a82d51ed24 ("ALSA: hda - Support
VGA-switcheroo").

v1.1: The changes above imply that in find_active_client() the call
to client_is_vga() is now superfluous. Drop it.

Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
[danvet: Add Takashi's clarification to the commit message.]
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-09-24 20:14:25 +02:00
Lukas Wunner
4127838c46 vga_switcheroo: Sort headers alphabetically
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-09-24 20:14:19 +02:00
Lukas Wunner
a645654b81 vga_switcheroo: Document _ALL_ the things!
This adds an "Overview" DOC section plus two DOC sections for the modes
of use ("Manual switching and manual power control" and "Driver power
control").

Also included is kernel-doc for all public functions, structs and enums.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-09-22 10:37:26 +02:00
Thierry Reding
798ae0f669 vga_switcheroo: Remove unnecessary checks
debugfs_remove() gracefully ignores NULL parameters, so the explicit
checks can be removed.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-08-12 17:13:19 +02:00
Thierry Reding
7491bfb446 vga_switcheroo: Wrap overly long lines
Wrap overly long lines to make checkpatch happy. While at it, also add
blank lines after declarations to eliminate additional problems flagged
by checkpatch.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-08-12 17:13:18 +02:00
Thierry Reding
9b0be1ebec vga_switcheroo: Use pr_fmt()
Use pr_fmt() to define the "vga_switcheroo: " prefix that is prepended
to all output messages emitted by pr_*() functions. This allows making
existing strings much shorter and eliminates a bunch of warnings from
checkpatch about lines being overly long.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-08-12 17:13:18 +02:00
Thierry Reding
7130927830 vga_switcheroo: Cleanup header comment
The header comment uses a weird combination of formatting styles. Make
it consistent.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-08-12 17:11:59 +02:00
Thierry Reding
bf8252b3fc vga_switcheroo: Use pr_*() instead of printk()
This silences a bunch of checkpatch warnings and makes the code shorter.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-08-12 17:11:59 +02:00
Thierry Reding
5d90ccf908 vgaarb: Fix a few checkpatch errors and warnings
Wrap overly long lines (offending lines were mostly comments, so trivial
to fix up) and a number of other coding style issues pointed out by the
checkpatch tool.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-08-12 17:11:58 +02:00
Thierry Reding
8b7e2e865f vgaarb: Use vgaarb: prefix consistently in messages
Define the pr_fmt() macro to causes all messages emitted by pr_*()
functions to be prefixed with "vgaarb: ".

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-08-12 17:11:58 +02:00
Thierry Reding
eb6944f2fc vgaarb: Stop complaining about absent devices
Some setups do not register a default VGA device, in which case the VGA
arbiter will still complain about the (non-existent) PCI device being a
non-VGA device.

Fix this by making the error message conditional on a default VGA device
having been set up. Note that the easy route of erroring out early isn't
going to work because otherwise priv->target won't be properly updated.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2015-08-12 17:11:57 +02:00
Linus Torvalds
faafcba3b5 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The main changes in this cycle were:

   - Optimized support for Intel "Cluster-on-Die" (CoD) topologies (Dave
     Hansen)

   - Various sched/idle refinements for better idle handling (Nicolas
     Pitre, Daniel Lezcano, Chuansheng Liu, Vincent Guittot)

   - sched/numa updates and optimizations (Rik van Riel)

   - sysbench speedup (Vincent Guittot)

   - capacity calculation cleanups/refactoring (Vincent Guittot)

   - Various cleanups to thread group iteration (Oleg Nesterov)

   - Double-rq-lock removal optimization and various refactorings
     (Kirill Tkhai)

   - various sched/deadline fixes

  ... and lots of other changes"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (72 commits)
  sched/dl: Use dl_bw_of() under rcu_read_lock_sched()
  sched/fair: Delete resched_cpu() from idle_balance()
  sched, time: Fix build error with 64 bit cputime_t on 32 bit systems
  sched: Improve sysbench performance by fixing spurious active migration
  sched/x86: Fix up typo in topology detection
  x86, sched: Add new topology for multi-NUMA-node CPUs
  sched/rt: Use resched_curr() in task_tick_rt()
  sched: Use rq->rd in sched_setaffinity() under RCU read lock
  sched: cleanup: Rename 'out_unlock' to 'out_free_new_mask'
  sched: Use dl_bw_of() under RCU read lock
  sched/fair: Remove duplicate code from can_migrate_task()
  sched, mips, ia64: Remove __ARCH_WANT_UNLOCKED_CTXSW
  sched: print_rq(): Don't use tasklist_lock
  sched: normalize_rt_tasks(): Don't use _irqsave for tasklist_lock, use task_rq_lock()
  sched: Fix the task-group check in tg_has_rt_tasks()
  sched/fair: Leverage the idle state info when choosing the "idlest" cpu
  sched: Let the scheduler see CPU idle states
  sched/deadline: Fix inter- exclusive cpusets migrations
  sched/deadline: Clear dl_entity params when setscheduling to different class
  sched/numa: Kill the wrong/dead TASK_DEAD check in task_numa_fault()
  ...
2014-10-13 16:23:15 +02:00
Linus Torvalds
1734a6e47f Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux
Pull drm fixes from Dave Airlie:
 "A bunch of radeon fixes for oops on module unload, and problems with
  resetting the dma engine, one nouveau fix for black boxes in rendering
  on my mbp retina, one sti fix, and a couple of intel fixes"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux:
  drm/nouveau: ltc/gf100-: fix cbc issues on certain boards
  drm/bochs: add missing drm_connector_register call
  drm/cirrus: add missing drm_connector_register call
  drm/radeon: Fix typo 'addr' -> 'entry' in rs400_gart_set_page
  drm/nouveau/runpm: fix module unload
  drm/radeon/px: fix module unload
  vgaswitcheroo: add vga_switcheroo_fini_domain_pm_ops
  drm/radeon: don't reset dma on r6xx-evergreen init
  drm/radeon: don't reset sdma on CIK init
  drm/radeon: don't reset dma on NI/SI init
  drm/radeon/dpm: fix resume on mullins
  drm/radeon: Disable HDP flush before every CS again for < r600
  drm/radeon: delete unused PTE_* defines
  drm/i915: Add limited color range readout for HDMI/DP ports on g4x/vlv/chv
  drm: sti: do not iterate over the info frame array
  drm/i915: Fix SRC_COPY width on 830/845g
2014-09-20 10:10:14 -07:00
Kirill Tkhai
f139caf2e8 sched, cleanup, treewide: Remove set_current_state(TASK_RUNNING) after schedule()
schedule(), io_schedule() and schedule_timeout() always return
with TASK_RUNNING state set, so one more setting is unnecessary.

(All places in patch are visible good, only exception is
 kiblnd_scheduler() from:

      drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c

 Its schedule() is one line above standard 3 lines of unified diff)

No places where set_current_state() is used for mb().

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1410529254.3569.23.camel@tkhai
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Anil Belur <askb23@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Kleikamp <shaggy@kernel.org>
Cc: David Airlie <airlied@linux.ie>
Cc: David Howells <dhowells@redhat.com>
Cc: Dmitry Eremin <dmitry.eremin@intel.com>
Cc: Frank Blaschka <blaschka@linux.vnet.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Isaac Huang <he.huang@intel.com>
Cc: James E.J. Bottomley <JBottomley@parallels.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: J. Bruce Fields <bfields@fieldses.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Liang Zhen <liang.zhen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Masaru Nomura <massa.nomura@gmail.com>
Cc: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Oleg Drokin <green@linuxhacker.ru>
Cc: Peng Tao <bergwolf@gmail.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Robert Love <robert.w.love@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Ursula Braun <ursula.braun@de.ibm.com>
Cc: Zi Shen Lim <zlim.lnx@gmail.com>
Cc: devel@driverdev.osuosl.org
Cc: dm-devel@redhat.com
Cc: dri-devel@lists.freedesktop.org
Cc: fcoe-devel@open-fcoe.org
Cc: jfs-discussion@lists.sourceforge.net
Cc: linux390@de.ibm.com
Cc: linux-afs@lists.infradead.org
Cc: linux-cris-kernel@axis.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-nfs@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linux-raid@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: qla2xxx-upstream@qlogic.com
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: user-mode-linux-user@lists.sourceforge.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-09-19 12:35:17 +02:00
Alex Deucher
766a53d059 vgaswitcheroo: add vga_switcheroo_fini_domain_pm_ops
Drivers should call this on unload to unregister pmops.

Bug:
https://bugzilla.kernel.org/show_bug.cgi?id=84431

Reviewed-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
2014-09-18 19:21:20 -04:00
Bruno Prémont
ce6eacb07e vgaarb: Drop obsolete #ifndef
Commit 20cde69402 ("x86, ia64: Move EFI_FB vga_default_device()
initialization to pci_vga_fixup()") moved boot video device detection from
efifb to x86 and ia64 pci/fixup.c.

Remove the left-over #ifndef check that will always match since the
corresponding arch-specific define is gone with above patch.

Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Matthew Garrett <matthew.garrett@nebula.com>
2014-09-16 15:02:55 -06:00
Bruno Prémont
86fd887b7f vgaarb: Don't default exclusively to first video device with mem+io
Commit 20cde69402 ("x86, ia64: Move EFI_FB vga_default_device()
initialization to pci_vga_fixup()") moved boot video device detection from
efifb to x86 and ia64 pci/fixup.c.

For dual-GPU Apple computers above change represents a regression as code
in efifb did forcefully override vga_default_device while the merge did not
(vgaarb happens prior to PCI fixup).

To improve on initial device selection by vgaarb (it cannot know if PCI
device not behind bridges see/decode legacy VGA I/O or not), move the
screen_info based check from pci_video_fixup() to vgaarb's init function and
use it to refine/override decision taken while adding the individual PCI
VGA devices.  This way PCI fixup has no reason to adjust vga_default_device
anymore but can depend on its value for flagging shadowed VBIOS.

This has the nice benefit of removing duplicated code but does introduce a
#if defined() block in vgaarb.  Not all architectures have screen_info and
would cause compile to fail without it.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=84461
Reported-and-Tested-By: Andreas Noever <andreas.noever@gmail.com>
Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Matthew Garrett <matthew.garrett@nebula.com>
CC: stable@vger.kernel.org # v3.5+
2014-09-16 13:06:18 -06:00
Alex Williamson
4e4e7dc55a vgaarb: We can own non-decoded resources
The VGA arbiter does not allow devices to "own" resources that it
doesn't "decode".  However, it does allow devices to "lock" resources
that it doesn't decode.  This gets us into trouble because locking
the resource goes through the same bridge routing updates regardless
of whether we decode the resource.  This means that when a non-decoded
resource is released, the bridge is left with VGA routing enabled and
locking a different device won't clear it.

This happens in the following scenario:

VGA device 01:00.0 (VGA1) is owned by the radeon driver, which
registers a set_vga_decode function which releases legacy VGA decodes.

VGA device 02:00.0 (VGA2) is any VGA device.

VGA1 user locks VGA resources triggering first_use callback of
set_vga_decoded, clearing "decode" and "owns" of legacy resources
on VGA1.

VGA1 user unlocks VGA resources.

VGA2 user locks VGA resources, which skips VGA1 as conflicting as it
does not "own" legacy resources, although VGA routing is still enabled
for the VGA1 bridge.  VGA routing is enabled on VGA2 bridge.

VGA2 may or may not receive VGA transactions depending on the bus
priority of VGA1 vs VGA2 bridge.

To resolve this, we need to allow devices to "own" resources that they
do not "decode".  This way we can track bus ownership of VGA.  When a
device decodes VGA, it only means that we must update the command bits
in cases where the conflicting device is on the same bus.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2014-07-08 11:15:09 +10:00
Alex Deucher
f2bc561610 vgaswitcheroo: switch the mux to the igp on power down when runpm is enabled
Avoids blank screens on muxed systems when runpm is active.

bug:
https://bugs.freedesktop.org/show_bug.cgi?id=75917

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
2014-06-02 10:25:08 -04:00
Alex Williamson
5c0f6ee766 vgaarb: Fix VGA decodes changes
When VGA decodes change we need to do a bit more evaluation of exactly what
has changed.  We don't necessarily give up all the old owns resources and
we need to account for resources with locks.  The new algorithm is: If
something is added, update decodes.  If legacy resources were added and
none were there before, we have a new participant.  If something is
removed, update decodes.  If we previously owned it, we no longer own it.
If it was previously locked, invalidate all locks and release it.  If
legacy resources were removed and none are left, remove the participant
from VGA arbitration.

Previously we updated decodes, released ownership of everything that was
previously decoded, ignored all locks, and went off looking for another
device to transfer VGA to.  In a test case where Intel IGD removes only
legacy VGA memory decoding, this left the arbiter switching to discrete
graphics without actually disabling legacy VGA IO from the IGD.  As a
bonus, we bumped up the count of VGA arbitration participants for no
good reason.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Cc: Dave Airlie <airlied@redhat.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
[danvet: Kill now unused variables, reported by the 0-day kernel
builtbot.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2013-09-03 19:17:59 +02:00
Alex Williamson
f22d776f3e vgaarb: Don't disable resources that are not owned
If a device does not own a resource then we don't need to disable it.
This resolves the case where an Intel IGD device can be configured to
disable decode of VGA memory but we still need the arbiter to handle
VGA I/O port routing.  When the IGD device is in conflict, only
PCI_COMMAND_IO should be disabled since VGA memory does not require
arbitration on this device.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Cc: Dave Airlie <airlied@redhat.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2013-09-03 19:17:58 +02:00
Dave Airlie
0d69704ae3 gpu/vga_switcheroo: add driver control power feature. (v3)
For optimus and powerxpress muxless we really want the GPU
driver deciding when to power up/down the GPU, not userspace.

This adds the ability for a driver to dynamically power up/down
the GPU and remove the switcheroo from controlling it, the
switcheroo reports the dynamic state to userspace also.

It also adds 2 power domains, one for machine where the power
switch is controlled outside the GPU D3 state, so the powerdown
ordering is done correctly, and the second for the hdmi audio
device to make sure it can resume for PCI config space accesses.

v1.1: fix build with switcheroo off

v2: add power domain support for radeon and v1 nvidia dsms
v2.1: fix typo in off case

v3: add audio power domain for hdmi audio + misc audio fixes

v4: use PCI_SLOT macro, drop power reference on hdmi audio resume
failure also.

Signed-off-by: Dave Airlie <airlied@redhat.com>
2013-08-29 13:30:21 +10:00
Dave Airlie
054430e773 fbcon: fix locking harder
Okay so Alan's patch handled the case where there was no registered fbcon,
however the other path entered in set_con2fb_map pit.

In there we called fbcon_takeover, but we also took the console lock in a couple
of places. So push the console lock out to the callers of set_con2fb_map,

this means fbmem and switcheroo needed to take the lock around the fb notifier
entry points that lead to this.

This should fix the efifb regression seen by Maarten.

Tested-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Tested-by: Lu Hua <huax.lu@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2013-02-08 12:02:43 +10:00
Linus Torvalds
3c2e81ef34 Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux
Pull DRM updates from Dave Airlie:
 "This is the one and only next pull for 3.8, we had a regression we
  found last week, so I was waiting for that to resolve itself, and I
  ended up with some Intel fixes on top as well.

  Highlights:
   - new driver: nvidia tegra 20/30/hdmi support
   - radeon: add support for previously unused DMA engines, more HDMI
     regs, eviction speeds ups and fixes
   - i915: HSW support enable, agp removal on GEN6, seqno wrapping
   - exynos: IPP subsystem support (image post proc), HDMI
   - nouveau: display class reworking, nv20->40 z compression
   - ttm: start of locking fixes, rcu usage for lookups,
   - core: documentation updates, docbook integration, monotonic clock
     usage, move from connector to object properties"

* 'drm-next' of git://people.freedesktop.org/~airlied/linux: (590 commits)
  drm/exynos: add gsc ipp driver
  drm/exynos: add rotator ipp driver
  drm/exynos: add fimc ipp driver
  drm/exynos: add iommu support for ipp
  drm/exynos: add ipp subsystem
  drm/exynos: support device tree for fimd
  radeon: fix regression with eviction since evict caching changes
  drm/radeon: add more pedantic checks in the CP DMA checker
  drm/radeon: bump version for CS ioctl support for async DMA
  drm/radeon: enable the async DMA rings in the CS ioctl
  drm/radeon: add VM CS parser support for async DMA on cayman/TN/SI
  drm/radeon/kms: add evergreen/cayman CS parser for async DMA (v2)
  drm/radeon/kms: add 6xx/7xx CS parser for async DMA (v2)
  drm/radeon: fix htile buffer size computation for command stream checker
  drm/radeon: fix fence locking in the pageflip callback
  drm/radeon: make indirect register access concurrency-safe
  drm/radeon: add W|RREG32_IDX for MM_INDEX|DATA based mmio accesss
  drm/exynos: support extended screen coordinate of fimd
  drm/exynos: fix x, y coordinates for right bottom pixel
  drm/exynos: fix fb offset calculation for plane
  ...
2012-12-17 08:26:17 -08:00
Jan Glauber
1150f25441 vga: compile fix, disable vga for s390
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2012-11-30 17:47:28 +01:00
Igor Murzov
9499c82da2 vga_switcheroo: Drop unused include and unused variables.
Signed-off-by: Igor Murzov <e-mail@date.by>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2012-11-20 16:06:29 +10:00
Bjorn Helgaas
78c8f84302 Merge branch 'pci/yinghai-misc' into next 2012-09-24 17:24:11 -06:00
Yinghai Lu
84544a1dea PCI: Fix default vga ref_count
when __ARCH_HAS_VGA_DEFAULT_DEVICE is not defined, aka EFIFB is not used,
for static path, vga_default setting is through vga_arbiter_add_pci_device.
and later x86 pci_fixup_video, will skip setting again.
- subsys_initcall(vga_arb_device_init) come first to call
vga_arbiter_add_pci_device. It will call pci_get_dev to hold one reference.

for hotplug add path, even vga_arbiter_add_pci_device is called via
notifier, but it will check VGA_RSRC_LEGACY_MASK that is not set for
hotplug path.  So x86 pci_fixup_video will take over to call
vga_set_default_device().  It will not hold one refrence.

Later for hotplug remove path, vga_arbiter_del_pci_device that does not
check VGA_RSRC_LEGACY_MASK will call put_device and it will cause ref_count
to decrease extra. that will have that pci device get deleted early
wrongly.

Need to make get/put balance for both cases.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: x86@kernel.org
Cc: Dave Airlie <airlied@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Julia Lawall <julia@diku.dk>
Cc: Matthew Garrett <mjg@redhat.com>
2012-09-24 13:35:00 -06:00
Bjorn Helgaas
b895e663f4 Merge branch 'pci/jiang-get-domain-bus-slot' into next
* pci/jiang-get-domain-bus-slot:
  xen-pcifront: Use hotplug-safe pci_get_domain_bus_and_slot()
  PCI: Use hotplug-safe pci_get_domain_bus_and_slot()
  PCI/cpcihp: Use hotplug-safe pci_get_domain_bus_and_slot()
  PCI/vga: Use hotplug-safe pci_get_domain_bus_and_slot()
  ia64/PCI: Use hotplug-safe pci_get_domain_bus_and_slot()
2012-09-17 15:44:20 -06:00
Jiang Liu
f85567c89e PCI/vga: Use hotplug-safe pci_get_domain_bus_and_slot()
Following code has a race window between pci_find_bus() and pci_get_slot()
if PCI hotplug operation happens between them which removes the pci_bus.
So use PCI hotplug safe interface pci_get_domain_bus_and_slot() instead,
which also reduces code complexity.

    struct pci_bus *pci_bus = pci_find_bus(domain, busno);
    struct pci_dev *pci_dev = pci_get_slot(pci_bus, devfn);

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
2012-09-12 14:13:11 -06:00
Seth Forshee
e99eac5e4e vga_switcheroo: Don't require handler init callback
This callback is a no-op in nouveau, and the upcoming apple-gmux
switcheroo support won't require it either. Rather than forcing drivers
to stub it out, just make it optional and remove the callback from
nouveau.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
2012-08-17 17:34:41 -04:00
Seth Forshee
36704c0c4c vga_switcheroo: Remove assumptions about registration/unregistration ordering
vga_switcheroo assumes that the handler will be registered before the
last client, otherwise switching will not be enabled. Likewise it's
assumed that the handler will not be unregistered without at least one
client also being unregistered, otherwise switching will remain enabled
despite no longer having a handler. These assumptions cannot be enforced
if the handler is in a separate driver from both clients, as with the
gmux found in Apple laptops. Remove this assumption.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
2012-08-17 17:34:41 -04:00
Takashi Iwai
c91c3faea5 vga_switcheroo: Enable/disable audio clients at the right time
The audio clients have to be disabled before disabling the VGA and
switching.  Similarly, enabling the audio client should be done at
last.  Otherwise the audio-side operation stalls, eventually leading
to Oops or lockups.

Tested-by: Jörg-Volker Peetz <jvpeetz@web.de>
Acked-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2012-06-09 12:14:43 +02:00
Takashi Iwai
c8e9cf7bb2 vga_switcheroo: Add a helper function to get the client state
Add vga_switcheroo_get_client_state() to get the current state of the
client.  This is necessary to determine the proper initial state of
audio clients in HD-audio driver.

Acked-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2012-06-08 11:24:12 +02:00
Takashi Iwai
3e9e63dbd3 vga_switcheroo: Add the support for audio clients
Add the support for audio clients to VGA-switcheroo for handling the
HDMI audio controller together with VGA switching.  The id of the
audio controller should be given explicitly at registration time
unlike the video controller.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43155

Signed-off-by: Takashi Iwai <tiwai@suse.de>
2012-05-13 11:27:21 +02:00
Takashi Iwai
26ec685ff9 vga_switcheroo: Introduce struct vga_switcheroo_client_ops
This changes the API as a clean-up.  Instead of passing multiple
function pointers at each time, introduce a new struct holding the
whole callback functions and pass it to the registration.

The same struct will be used for the upcoming audio client
registration, too.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
2012-05-13 11:24:09 +02:00
Takashi Iwai
79721e0a91 vga_switcheroo: Refactor using linked list
Refactor the code base a bit for the further work to adapt more clients.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
2012-05-13 11:21:56 +02:00
Matthew Garrett
1b23170a8e vga: fix build when fbdev is a module
This fixes the build breakage reported by Stephen in -next
when merging the drm-next tree.

Signed-off-by: Dave Airlie <airlied@redhat.com>
2012-04-24 09:50:21 +01:00
Dave Airlie
343d4a79fd vga-switcheroo: select VGA arbitration.
Since Matthew's changes we have to select arbitration.

Reported-by: devh on #radeon
Signed-off-by: Dave Airlie <airlied@redhat.com>
2012-04-24 09:50:19 +01:00
Matthew Garrett
2fbe8c7c3e vga-switcheroo: Use vga_default_device()
vga-switcheroo currently changes the default VGA device by fiddling with
the IORESOURCE_ROM_SHADOW flag on the device. This isn't strictly accurate,
since there's no guarantee that switching also changes the ROM decoding.
Switch over to using the vgaarb functions for this.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2012-04-24 09:50:16 +01:00
Matthew Garrett
1a39b310e9 vgaarb: Add support for setting the default video device (v2)
The default VGA device is a somewhat fluid concept on platforms with
multiple GPUs. Add support for setting it so switching code can update
things appropriately, and make sure that the sysfs code returns the right
device if it's changed.

v2: Updated to fix builds when __ARCH_HAS_VGA_DEFAULT_DEVICE is false.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: benh@kernel.crashing.org
Cc: airlied@redhat.com
Signed-off-by: Dave Airlie <airlied@redhat.com>
2012-04-24 09:50:15 +01:00
Julia Lawall
c916874d60 drivers/gpu/vga/vgaarb.c: add missing kfree
kbuf is a buffer that is local to this function, so all of the error paths
leaving the function should release it.

Signed-off-by: Julia Lawall <julia@diku.dk>
Cc: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-11-22 20:21:10 +00:00
Dave Airlie
f6252114cb vgaarb: a NULL bridge is acceptable for root devices.
I assumed all PCI buses had a bridge, but playing with qemu recently, I
discovered vgaarb bug where it wasn't detecting both devices shared a bridge
at the root level.

Don't check for NULL, if two buses have a NULL bridge, assume they share the
root bus.

Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-11-14 10:03:15 +00:00
Rakib Mullick
f35119d668 drivers: use kzalloc/kcalloc instead of 'kmalloc+memset', where possible
Signed-off-by: Rakib Mullick <rakib.mullick@gmail.com>
Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Tejun Heo <tj@kernel.org>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-07-25 20:57:13 -07:00
Linus Torvalds
98b98d3163 Merge branch 'drm-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6
* 'drm-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6: (169 commits)
  drivers/gpu/drm/radeon/atom.c: fix warning
  drm/radeon/kms: bump kms version number
  drm/radeon/kms: properly set num banks for fusion asics
  drm/radeon/kms/atom: move dig phy init out of modesetting
  drm/radeon/kms/cayman: fix typo in register mask
  drm/radeon/kms: fix typo in spread spectrum code
  drm/radeon/kms: fix tile_config value reported to userspace on cayman.
  drm/radeon/kms: fix incorrect comparison in cayman setup code.
  drm/radeon/kms: add wait idle ioctl for eg->cayman
  drm/radeon/cayman: setup hdp to invalidate and flush when asked
  drm/radeon/evergreen/btc/fusion: setup hdp to invalidate and flush when asked
  agp/uninorth: Fix lockups with radeon KMS and >1x.
  drm/radeon/kms: the SS_Id field in the LCD table if for LVDS only
  drm/radeon/kms: properly set the CLK_REF bit for DCE3 devices
  drm/radeon/kms: fixup eDP connector handling
  drm/radeon/kms: bail early for eDP in hotplug callback
  drm/radeon/kms: simplify hotplug handler logic
  drm/radeon/kms: rewrite DP handling
  drm/radeon/kms/atom: add support for setting DP panel mode
  drm/radeon/kms: atombios.h updates for DP panel mode
  ...
2011-05-24 12:06:40 -07:00
Florian Mickler
a67b8887ce vga_switcheroo: don't toggle-switch devices
If the requested device is already active, ignore the request.

This restores the original behaviour of the interface. The change was
probably an unintended side effect of

commit 66b37c6777 vga_switcheroo: split switching into two stages

which did not take into account to duplicate the !active check in the split-off
stage2.

Fix this by factoring that check out of stage1 into the debugfs_write routine.

References: https://bugzilla.kernel.org/show_bug.cgi?id=34252
Reported-by: Igor Murzov <e-mail@date.by>
Tested-by: Igor Murzov <e-mail@date.by>
Signed-off-by: Florian Mickler <florian@mickler.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-05-16 08:57:04 +10:00
Dave Airlie
3448a19da4 vgaarb: use bridges to control VGA routing where possible.
So in a lot of modern systems, a GPU will always be below a parent bridge that won't share with any other GPUs. This means VGA arbitration on those GPUs can be controlled by using the bridge routing instead of io/mem decodes.

The problem is locating which GPUs share which upstream bridges. This patch attempts to identify all the GPUs which can be controlled via bridges, and ones that can't. This patch endeavours to work out the bridge sharing semantics.

When disabling GPUs via a bridge, it doesn't do irq callbacks or touch the io/mem decodes for the gpu.

Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-05-04 13:38:46 +10:00
Alex Williamson
d4a3b10c16 vga_switcheroo: Remove unbalanced pci_enable_device
This is unbalanced and probably more fitting for the client
to take care of.  Remove it.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-05-04 13:46:01 +10:00
Lucas De Marchi
25985edced Fix common misspellings
Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-31 11:26:23 -03:00
Chris Wilson
8a327f23e2 Merge remote branch 'linus/master' into drm-intel-fixes
Merge with Linus to resolve conflicting fixes for the reusing the stale
HEAD value during intel_ring_wait().

Conflicts:
	drivers/gpu/drm/i915/intel_ringbuffer.c
2011-01-24 18:27:32 +00:00
Chris Wilson
934f992c76 drm/i915: Recognise non-VGA display devices
Starting with SandyBridge (though possible with earlier hacked BIOSes),
the BIOS may initialise the IGFX as secondary to a discrete GPU. Prior,
it would simply disable the integrated GPU. So we adjust our PCI class
mask to match any DISPLAY_CLASS device.

In such a configuration, the IGFX is not a primary VGA controller and
so should not take part in VGA arbitration, and the error return from
vga_client_register() is expected.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
2011-01-23 12:52:16 +00:00
David Rientjes
6a108a14fa kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT
The meaning of CONFIG_EMBEDDED has long since been obsoleted; the option
is used to configure any non-standard kernel with a much larger scope than
only small devices.

This patch renames the option to CONFIG_EXPERT in init/Kconfig and fixes
references to the option throughout the kernel.  A new CONFIG_EMBEDDED
option is added that automatically selects CONFIG_EXPERT when enabled and
can be used in the future to isolate options that should only be
considered for embedded systems (RISC architectures, SLOB, etc).

Calling the option "EXPERT" more accurately represents its intention: only
expert users who understand the impact of the configuration changes they
are making should enable it.

Reviewed-by: Ingo Molnar <mingo@elte.hu>
Acked-by: David Woodhouse <david.woodhouse@intel.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Greg KH <gregkh@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Robin Holt <holt@sgi.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-20 17:02:05 -08:00
Dan Carpenter
fea6f330cd vga_switcheroo: comparing too few characters in strncmp()
This is a copy-and-paste bug.  We should be comparing 4 characters here
instead of 3.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-01-07 15:29:37 +10:00
Dave Airlie
66b37c6777 vga_switcheroo: split switching into two stages.
stage 1: turn card on, switch boot vga pointer.
stage 2: switch fbs, switch mux and power off old card.

Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-01-05 13:45:46 +10:00
Dave Airlie
8d608aa629 vga_switcheroo: add reprobe hook for fbcon to recheck connected outputs.
This adds a hook after the mux is switched for the driver to reprobe
the connected outputs.

Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-01-05 13:44:07 +10:00
Dave Airlie
851ab954da vga_switcheroo: add debugging mux switch option.
This allows the mux to be switched from userspace using MIGD/MDIS
command to the switch.

Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-01-05 13:43:15 +10:00
Dave Airlie
5cfb3c3a10 vga_switcheroo: make power switch handler optional
At least on the nvidia mux the power switch seems to be executed
by the ACPI PS0/PS3 methods so need to do it explicitly.

Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-01-05 13:43:05 +10:00
Dave Airlie
6c2df40ec0 vga_switcheroo: print the IGD/DIS flag in the debugfs output.
We really want to see this so we can confirm that we pick the right one.

Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-01-05 13:42:59 +10:00
Linus Torvalds
092e0e7e52 Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl
* 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl:
  vfs: make no_llseek the default
  vfs: don't use BKL in default_llseek
  llseek: automatically add .llseek fop
  libfs: use generic_file_llseek for simple_attr
  mac80211: disallow seeks in minstrel debug code
  lirc: make chardev nonseekable
  viotape: use noop_llseek
  raw: use explicit llseek file operations
  ibmasmfs: use generic_file_llseek
  spufs: use llseek in all file operations
  arm/omap: use generic_file_llseek in iommu_debug
  lkdtm: use generic_file_llseek in debugfs
  net/wireless: use generic_file_llseek in debugfs
  drm: use noop_llseek
2010-10-22 10:52:56 -07:00
Arnd Bergmann
6038f373a3 llseek: automatically add .llseek fop
All file_operations should get a .llseek operation so we can make
nonseekable_open the default for future file operations without a
.llseek pointer.

The three cases that we can automatically detect are no_llseek, seq_lseek
and default_llseek. For cases where we can we can automatically prove that
the file offset is always ignored, we use noop_llseek, which maintains
the current behavior of not returning an error from a seek.

New drivers should normally not use noop_llseek but instead use no_llseek
and call nonseekable_open at open time.  Existing drivers can be converted
to do the same when the maintainer knows for certain that no user code
relies on calling seek on the device file.

The generated code is often incorrectly indented and right now contains
comments that clarify for each added line why a specific variant was
chosen. In the version that gets submitted upstream, the comments will
be gone and I will manually fix the indentation, because there does not
seem to be a way to do that using coccinelle.

Some amount of new code is currently sitting in linux-next that should get
the same modifications, which I will do at the end of the merge window.

Many thanks to Julia Lawall for helping me learn to write a semantic
patch that does all this.

===== begin semantic patch =====
// This adds an llseek= method to all file operations,
// as a preparation for making no_llseek the default.
//
// The rules are
// - use no_llseek explicitly if we do nonseekable_open
// - use seq_lseek for sequential files
// - use default_llseek if we know we access f_pos
// - use noop_llseek if we know we don't access f_pos,
//   but we still want to allow users to call lseek
//
@ open1 exists @
identifier nested_open;
@@
nested_open(...)
{
<+...
nonseekable_open(...)
...+>
}

@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
<+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+>
}

@ read disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
<+...
(
   *off = E
|
   *off += E
|
   func(..., off, ...)
|
   E = *off
)
...+>
}

@ read_no_fpos disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
... when != off
}

@ write @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
<+...
(
  *off = E
|
  *off += E
|
  func(..., off, ...)
|
  E = *off
)
...+>
}

@ write_no_fpos @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
... when != off
}

@ fops0 @
identifier fops;
@@
struct file_operations fops = {
 ...
};

@ has_llseek depends on fops0 @
identifier fops0.fops;
identifier llseek_f;
@@
struct file_operations fops = {
...
 .llseek = llseek_f,
...
};

@ has_read depends on fops0 @
identifier fops0.fops;
identifier read_f;
@@
struct file_operations fops = {
...
 .read = read_f,
...
};

@ has_write depends on fops0 @
identifier fops0.fops;
identifier write_f;
@@
struct file_operations fops = {
...
 .write = write_f,
...
};

@ has_open depends on fops0 @
identifier fops0.fops;
identifier open_f;
@@
struct file_operations fops = {
...
 .open = open_f,
...
};

// use no_llseek if we call nonseekable_open
////////////////////////////////////////////
@ nonseekable1 depends on !has_llseek && has_open @
identifier fops0.fops;
identifier nso ~= "nonseekable_open";
@@
struct file_operations fops = {
...  .open = nso, ...
+.llseek = no_llseek, /* nonseekable */
};

@ nonseekable2 depends on !has_llseek @
identifier fops0.fops;
identifier open.open_f;
@@
struct file_operations fops = {
...  .open = open_f, ...
+.llseek = no_llseek, /* open uses nonseekable */
};

// use seq_lseek for sequential files
/////////////////////////////////////
@ seq depends on !has_llseek @
identifier fops0.fops;
identifier sr ~= "seq_read";
@@
struct file_operations fops = {
...  .read = sr, ...
+.llseek = seq_lseek, /* we have seq_read */
};

// use default_llseek if there is a readdir
///////////////////////////////////////////
@ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier readdir_e;
@@
// any other fop is used that changes pos
struct file_operations fops = {
... .readdir = readdir_e, ...
+.llseek = default_llseek, /* readdir is present */
};

// use default_llseek if at least one of read/write touches f_pos
/////////////////////////////////////////////////////////////////
@ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read.read_f;
@@
// read fops use offset
struct file_operations fops = {
... .read = read_f, ...
+.llseek = default_llseek, /* read accesses f_pos */
};

@ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write.write_f;
@@
// write fops use offset
struct file_operations fops = {
... .write = write_f, ...
+	.llseek = default_llseek, /* write accesses f_pos */
};

// Use noop_llseek if neither read nor write accesses f_pos
///////////////////////////////////////////////////////////

@ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
identifier write_no_fpos.write_f;
@@
// write fops use offset
struct file_operations fops = {
...
 .write = write_f,
 .read = read_f,
...
+.llseek = noop_llseek, /* read and write both use no f_pos */
};

@ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write_no_fpos.write_f;
@@
struct file_operations fops = {
... .write = write_f, ...
+.llseek = noop_llseek, /* write uses no f_pos */
};

@ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
@@
struct file_operations fops = {
... .read = read_f, ...
+.llseek = noop_llseek, /* read uses no f_pos */
};

@ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Julia Lawall <julia@diku.dk>
Cc: Christoph Hellwig <hch@infradead.org>
2010-10-15 15:53:27 +02:00
Daniel J Blueman
201ba4c432 vgaarb: trivial fix
Correct function being needlessly visible outside compilation unit
when the only users are internal.

Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-09-24 10:13:44 +10:00
Tiago Vignatti
c0db9cbc73 vgaarb: use MIT license
Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
Cc: Henry Zhao <Henry.Zhao@Sun.COM>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-06-03 13:13:34 +10:00
Tiago Vignatti
2d6e9b9197 vgaarb: convert pr_devel() to pr_debug()
We want to be able to use CONFIG_DYNAMIC_DEBUG in arbiter code, switch
the few existing pr_devel() calls to pr_debug().

Also, add one more debug information regarding decoding count.

Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-06-03 13:13:33 +10:00
Dave Airlie
05ea893c46 Merge remote branch 'anholt/drm-intel-next' into drm-next
* anholt/drm-intel-next: (515 commits)
  drm/i915: Fix out of tree builds
  drm/i915: move fence lru to struct drm_i915_fence_reg
  drm/i915: don't allow tiling changes on pinned buffers v2
  drm/i915: Be extra careful about A/D matching for multifunction SDVO
  drm/i915: Fix DDC bus selection for multifunction SDVO
  drm/i915: cleanup mode setting before unmapping registers
  drm/i915: Make fbc control wrapper functions
  drm/i915: Wait for the GPU whilst shrinking, if truly desperate.
  drm/i915: Use spatio-temporal dithering on PCH
  [MTD] Remove zero-length files mtdbdi.c and internal.ho
  pata_pcmcia / ide-cs: Fix bad hashes for Transcend and kingston IDs
  libata: Fix several inaccuracies in developer's guide
  slub: Fix bad boundary check in init_kmem_cache_nodes()
  raid6: fix recovery performance regression
  KEYS: call_sbin_request_key() must write lock keyrings before modifying them
  KEYS: Use RCU dereference wrappers in keyring key type code
  KEYS: find_keyring_by_name() can gain access to a freed keyring
  ALSA: hda: Fix 0 dB for Packard Bell models using Conexant CX20549 (Venice)
  ALSA: hda - Add quirk for Dell Inspiron 19T using a Conexant CX20582
  ALSA: take tu->qlock with irqs disabled
  ...
2010-05-19 09:35:51 +10:00
Randy Dunlap
ca117d6df9 vga: fix kconfig text typos
Fix typos in vga/Kconfig file
and use GPU (upper case) consistently.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-05-18 15:55:31 +10:00
Linus Torvalds
7ebd467551 Merge branch 'drm-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6
* 'drm-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
  drm/radeon/kms/legacy: only enable load detection property on DVI-I
  drm/radeon/kms: fix panel scaling adjusted mode setup
  drivers/gpu/drm/drm_sysfs.c: sysfs files error handling
  drivers/gpu/drm/radeon/radeon_atombios.c: range check issues
  gpu: vga_switcheroo, fix lock imbalance
  drivers/gpu/drm/drm_memory.c: fix check for end of loop
  drivers/gpu/drm/via/via_video.c: fix off by one issue
  drm/radeon/kms/agp The wrong AGP chipset can cause a NULL pointer dereference
  drm/radeon/kms: r300 fix CS checker to allow zbuffer-only fastfill
2010-05-04 19:08:12 -07:00
Jiri Slaby
8c88e50bcf gpu: vga_switcheroo, fix lock imbalance
Stanse found that one error path in vga_switcheroo_debugfs_write omits to
unlock vgasr_mutex.  Fix that.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-04-28 18:41:52 +10:00
Tejun Heo
5a0e3ad6af include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00
Linus Torvalds
03a2c4d76c Merge branch 'drm-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6
* 'drm-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6: (151 commits)
  vga_switcheroo: disable default y by new rules.
  drm/nouveau: fix *staging* driver build with switcheroo off.
  drm/radeon: fix typo in Makefile
  vga_switcheroo: fix build on platforms with no ACPI
  drm/radeon: Fix printf type warning in 64bit system.
  drm/radeon/kms: bump the KMS version number for square tiling support.
  vga_switcheroo: initial implementation (v15)
  drm/radeon/kms: do not disable audio engine twice
  Revert "drm/radeon/kms: disable HDMI audio for now on rv710/rv730"
  drm/radeon/kms: do not preset audio stuff and start timer when not using audio
  drm/radeon: r100/r200 ums: block ability for userspace app to trash 0 page and beyond
  drm/ttm: fix function prototype to match implementation
  drm/radeon: use ALIGN instead of open coding it
  drm/radeon/kms: initialize set_surface_reg reg for rs600 asic
  drm/i915: Use a dmi quirk to skip a broken SDVO TV output.
  drm/i915: enable/disable LVDS port at DPMS time
  drm/i915: check for multiple write domains in pin_and_relocate
  drm/i915: clean-up i915_gem_flush_gpu_write_domain
  drm/i915: reuse i915_gpu_idle helper
  drm/i915: ensure lru ordering of fence_list
  ...

Fixed trivial conflicts in drivers/gpu/vga/Kconfig
2010-03-04 07:49:37 -08:00
Dave Airlie
d424b925f7 vga_switcheroo: disable default y by new rules.
Another undocumented rule of kernel folklore, no default y
config options anymore, apparantly hinting to distros they might
want something isn't preferred anymore.

Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-03-03 09:26:35 +10:00
Dave Airlie
8edb381d67 vga_switcheroo: fix build on platforms with no ACPI
radeon was always including the atpx code unnecessarily, also core
switcheroo was including acpi headers.

Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-03-01 22:21:58 +11:00
Dave Airlie
6a9ee8af34 vga_switcheroo: initial implementation (v15)
Many new laptops now come with 2 gpus, one to be used for low power
modes and one for gaming/on-ac applications. These GPUs are typically
wired to the laptop panel and VGA ports via a multiplexer unit which
is controlled via ACPI methods.

4 combinations of systems typically exist - with 2 ACPI methods.
Intel/ATI - Lenovo W500/T500 - use ATPX ACPI method
ATI/ATI - some ASUS - use ATPX ACPI Method
Intel/Nvidia - - use _DSM ACPI method
Nvidia/Nvidia -  - use _DSM ACPI method.

TODO:
This patch adds support for the ATPX method and initial bits
for the _DSM methods that need to written by someone with
access to the hardware.
Add a proper non-debugfs interface - need to get some proper
testing first.

v2: add power up/down support for both devices
on W500 puts i915/radeon into D3 and cuts power to radeon.

v3: redo probing methods, no DMI list, drm devices call to
register with switcheroo, it tries to find an ATPX method on
any device and once there is two devices + ATPX it inits the
switcher.

v4: ATPX msg handling using buffers - should work on more machines

v5: rearchitect after more mjg59 discussion - move ATPX handling to
    radeon driver.

v6: add file headers + initial nouveau bits (to be filled out).

v7: merge delayed switcher code.

v8: avoid suspend/resume of gpu that is off

v9: rearchitect - mjg59 is always right. - move all ATPX code to
radeon, should allow simpler DSM also proper ATRM handling

v10: add ATRM support for radeon BIOS, add mutex to lock vgasr_priv

v11: fix bug in resuming Intel for 2nd time.

v12: start fixing up nvidia code blindly.

v13: blindly guess at finishing nvidia code

v14: remove radeon audio hacks - fix up intel resume more like upstream

v15: clean up printks + remove unnecessary igd/dis pointers

mount debugfs

/sys/kernel/debug/vgaswitcheroo/switch - should exist if ATPX detected
 + 2 cards.

DIS - immediate change to discrete
IGD - immediate change to IGD
DDIS - delayed change to discrete
DIGD - delayed change to IGD
ON - turn on not in use
OFF - turn off not in use

Tested on W500 (Intel/ATI) and T500 (Intel/ATI)

Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-03-01 16:20:37 +10:00
Linus Torvalds
c7e15899d0 Merge branch 'x86-pci-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-pci-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Enable NMI on all cpus on UV
  vgaarb: Add user selectability of the number of GPUS in a system
  vgaarb: Fix VGA arbiter to accept PCI domains other than 0
  x86, uv: Update UV arch to target Legacy VGA I/O correctly.
  pci: Update pci_set_vga_state() to call arch functions
2010-02-28 10:59:18 -08:00
Kyle McMartin
2cc9116c2b vgaarb: fix "target=default" passing
Commit 77c1ff3982 fixed the userspace
pointer dereference, but introduced another bug pointed out by Eugene Teo
in RH bug #564264. Instead of comparing the point we were at in the string,
we instead compared the beginning of the string to "default".

Signed-off-by: Kyle McMartin <kyle@redhat.com>
Reported-by: Eugene Teo <eteo@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-02-20 07:28:04 +10:00
Andy Getzendanner
77c1ff3982 vgaarb: fix incorrect dereference of userspace pointer.
This patch corrects a userspace pointer dereference in the VGA arbiter
in 2.6.32.1.

copy_from_user() is used at line 822 to copy the contents of buf into
kbuf, but a call to strncmp() on line 964 uses buf rather than kbuf.  This
problem led to a GPF in strncmp() when X was started on my x86_32 systems.
 X triggered the behavior with a write of "target PCI:0000:01:00.0" to
/dev/vga_arbiter.

The patch has been tested against 2.6.32.1 and observed to correct the GPF
observed when starting X or manually writing the string "target
PCI:0000:01:00.0" to /dev/vga_arbiter.

Signed-off-by: Andy Getzendanner <james.getzendanner@students.olin.edu>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-02-11 14:04:48 +10:00
Mike Travis
36028f3383 vgaarb: Add user selectability of the number of GPUS in a system
Update the VGA Arbiter to allow the user to select the number
of GPU's supported in a system.

v2: simplify setting of MAX_USER_CARDS, revert back to original default of 16

Signed-off-by: Mike Travis <travis@sgi.com>
LKML-Reference: <4B68D51D.6090401@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Robin Holt <holt@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: David Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2010-02-05 15:02:47 -08:00
Mike Travis
773a38dbda vgaarb: Fix VGA arbiter to accept PCI domains other than 0
Update the VGA Arbiter to accept PCI Domains other than 0.

Signed-off-by: Mike Travis <travis@sgi.com>
LKML-Reference: <201002022238.o12McFe8018730@imap1.linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Robin Holt <holt@sgi.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: David Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2010-02-05 14:05:41 -08:00
Dave Airlie
6ac3bd5270 PCI/vgaarb: cleanup some warnings + cleanup some comments.
Fix some warnings reported in linux-next + also cleanup some
comment errors noticed by Pekka Paalanen.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
2009-09-09 13:29:41 -07:00
Benjamin Herrenschmidt
deb2d2ecd4 PCI/GPU: implement VGA arbitration on Linux
Background:
Graphic devices are accessed through ranges in I/O or memory space. While most
modern devices allow relocation of such ranges, some "Legacy" VGA devices
implemented on PCI will typically have the same "hard-decoded" addresses as
they did on ISA. For more details see "PCI Bus Binding to IEEE Std 1275-1994
Standard for Boot (Initialization Configuration) Firmware Revision 2.1"
Section 7, Legacy Devices.

The Resource Access Control (RAC) module inside the X server currently does
the task of arbitration when more than one legacy device co-exists on the same
machine. But the problem happens when these devices are trying to be accessed
by different userspace clients (e.g. two server in parallel). Their address
assignments conflict. Therefore an arbitration scheme _outside_ of the X
server is needed to control the sharing of these resources. This document
introduces the operation of the VGA arbiter implemented for Linux kernel.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Tiago Vignatti <tiago.vignatti@nokia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
2009-09-09 13:29:36 -07:00