This fixes a regression for SDVO from
commit fbfcc4f3a0
Author: Jani Nikula <jani.nikula@intel.com>
Date: Mon Oct 22 16:12:18 2012 +0300
drm/i915/sdvo: restore i2c adapter config on intel_sdvo_init() failures
As SDVOB and SDVOC are multiplexed on the same pin, if a chipset does
not have the second SDVO encoder, it will then remove the force-bit
setting on the common i2c adapter during teardown. All subsequent
attempts of trying to use GMBUS with SDVOB then fail.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
[danvet: fixup inversion in the debug printout, noticed by Jani
Nikulai.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Convert #include "..." to #include <path/...> in drivers/gpu/.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>
Remove redundant DRM UAPI header #inclusions from drivers/gpu/.
Remove redundant #inclusions of core DRM UAPI headers (drm.h, drm_mode.h and
drm_sarea.h). They are now #included via drmP.h and drm_crtc.h via a preceding
patch.
Without this patch and the patch to make include the UAPI headers from the core
headers, after the UAPI split, the DRM C sources cannot find these UAPI headers
because the DRM code relies on specific -I flags to make #include "..." work
on headers in include/drm/ - but that does not work after the UAPI split without
adding more -I flags.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>
i2c_add_adapter() may do i2c transfers on the bus to detect supported
devices. Therefore the adapter needs to be all set before adding it. This
was not the case for the bit-banging fallback, resulting in an oops if the
device detection GMBUS transfers timed out. Fix the issue by calling
i2c_add_adapter() only after intel_gpio_setup().
LKML-Reference: <5021F00B.7000503@ionic.de>
Tested-by: Mihai Moldovan <ionic@ionic.de>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
drv_priv->gmbus is an array. Comparing it with NULL is somewhat less useful
than a chocolate teapot.
Possibly we should be testing bus != NULL each iteration of the loop
instead ?
gcc could help by warning too!
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
... flaky ddc hardware can cause a spurious NAK, resulting in the i2c
core and drm edid functions not trying to retry the edid transfer.
Luckily the gmbus quiescenting also times out for these cases, so we
can get out of this mess by returning -ETIMEDOUT for this specific
case. This way we keep the fast-fail of returning -ENXIO if there is
no device present, speeding up the boot process.
This regression has been introduced in
commit e646d57735
Author: Daniel Kurtz <djkurtz@chromium.org>
Date: Fri Mar 30 19:46:38 2012 +0800
drm/i915/intel_i2c: always wait for IDLE before clearing NAK
v2: Return -ETIMEDOUT for this case and keep the -ENXIO for real NAKs,
suggested by Daniel Kurtz.
Cc: Daniel Kurtz <djkurtz@chromium.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49518
Reported-and-Tested-by: Julian Simioni <julian.simioni@gmail.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The hw just returns garbage.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49838
Reported-and-tested-by: Vladyslav <DFEW.Entwickler@googlemail.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Some of these messages can be hit when userspace tries to probe the i2c
with nothing connected or if the driver code tries to do the same.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=48248
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
A common method of probing an i2c bus is trying to do a zero-length read.
Handle this case by checking the length first waiting for data to be read.
This is actually important, since attempting a zero-length read is one
of the ways that i2cdetect and i2c_new_probed_device detect whether
there is device present on the bus with a given address.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=48269
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The POSTING_READ() calls were originally added to make sure the writes
were flushed before any timing delays and across loops.
Now that the code has settled a bit, let's remove them.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Save the GMBUS2 value read while polling for state changes, and then
reuse this value when determining for which reason the loops were exited.
This is a small optimization which saves a couple of bus accesses for
memory mapped IO registers.
To avoid "assigning in if clause" checkpatch errors", use a ret variable
to store the wait_for macro return value.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
It is very common for an i2c device to require a small 1 or 2 byte write
followed by a read. For example, when reading from an i2c EEPROM it is
common to write and address, offset or index followed by a reading some
values.
The i915 gmbus controller provides a special "INDEX" cycle for performing
such a small write followed by a read. The INDEX can be either one or two
bytes long. The advantage of using such a cycle is that the CPU has
slightly less work to do once the read with INDEX cycle is started.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The i915 is only able to generate a STOP cycle (i.e. finalize an i2c
transaction) during a DATA or WAIT phase. In other words, the
controller rejects a STOP requested as part of the first transaction in a
sequence.
Thus, for the first transaction we must always use a WAIT cycle, detect
when the device has finished (and is in a WAIT phase), and then either
start the next transaction, or, if there are no more transactions,
generate a STOP cycle.
Note: Theoretically, the last transaction of a multi-transaction sequence
could initiate a STOP cycle. However, this slight optimization is left
for another patch. We return -ETIMEDOUT if the hardware doesn't
deactivate after the STOP cycle.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
[danvet: added comment to the code that gmbus can't generate STOP on
the very first cycle.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The GMBUS controller can report a NAK condition while a transaction is
still active. If the driver is fast enough, and the bus is slow enough,
the driver may clear the NAK condition while the controller is still
busy, resulting in a confused GMBUS controller. This will leave the
controller in a bad state such that the next transaction may fail.
Also, return -ENXIO if a device NAKs a transaction.
Note: this patch also refactors gmbus_xfer to remove the "done" label.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The GMBUS controller GMBUS3 register is double-buffered. Take advantage
of this by writing two 4-byte words before the first wait for HW_RDY.
This helps keep the GMBUS controller from becoming idle during long writes.
In fact, during experiments using the GMBUS interrupts, the HW_RDY
interrupt would only trigger for transactions >4 bytes after 2 writes
to GMBUS3.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
A common method of probing an i2c bus is trying to do a zero-length write.
Handle this case by checking the length first before decrementing it.
This is actually important, since attempting a zero-length write is one
of the ways that i2cdetect and i2c_new_probed_device detect whether
there is device present on the bus with a given address.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This memory is always allocated, and it is always a fixed size, so just
allocate it along with the rest of the driver state.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
There is no GMBUS "disabled" port 0, nor "reserved" port 7.
For the other 6 ports there is a fixed 1:1 mapping between pin pairs and
gmbus ports, which means every real gmbus port has a gpio pin.
Given these realizations, clean up gmbus initialization.
Tested on Sandybridge (gen 6, PCH == CougarPoint) hardware.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Instead of letting other modules directly access the ->gmbus array,
introduce intel_gmbus_get_adapter() for looking up an i2c_adapter
for a given gmbus port identifier. This will enable later refactoring
of the gmbus port list.
Note: Before requesting an adapter for a given gmbus port number, the
driver must first check its validity using i2c_intel_gmbus_is_port_valid().
If this check fails, a call to intel_gmbus_get_adapter() will WARN_ON and
return NULL. This is relevant for parts of the driver that read a port
from VBIOS, which might be improperly initialized and contain an invalid
port. In these cases, the driver must fall back to using a safer default
port.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Instead of rolling our own custom quirk_xfer function, use the bit_algo
pre_xfer and post_xfer functions to setup and teardown bit-banged
i2c transactions.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
According to i915 documentation [1], "Port D" (DP/HDMI Port D) is
actually gmbus pin pair 6 (gmbus0.2:0 == 110b GPIOF), not 7 (111b).
Pin pair 7 is a reserved pair.
[1] Documentation for [DevSNB+] and [DevIBX], as found on
http://intellinuxgraphics.org:
[DevSNB+]:
http://intellinuxgraphics.org/documentation/SNB/IHD_OS_Vol3_Part3.pdf
Section 2.2.2 lists the 6 gmbus ports (gpio pin pairs):
[ 5: HDMI/DPD, 4: HDMIB, 3: HDMI/DPC, 2: LVDS, 1: SSC, 0: VGA ]
2.2.2.1 lists the GPIO registers to control these 6 ports.
2.2.3.1 lists the mapping between 5 of these gmbus ports and the 3
Pin_Pair_Select bits (of the GMBUS0 register). This table is missing
HDMIB (port 101).
[DevIBX]: http://intellinuxgraphics.org/IHD_OS_Vol3_Part3r2.pdf
Section 2.2.2 lists the same 6 gmbus ports plus two 'reserved' gpio
ports.
2.2.2.1 lists 8 GPIO registers... however, it says the size of the
block is 6x32, which implies that those 2 reserved GPIO registers
(GPIO_6 & GPIO_7) don't actually exist (or are irrelevant).
2.2.3.1 lists the mapping between the 6 named gmbus ports and the 3
Pin_Pair_Select bits (of the GMBUS0 register). This table has HDMIB.
Note: the "reserved" and "disabled" pairs do not actually map to a
physical pair of pins, nor GPIO regs and shouldn't be initialized or used.
Fixing this is left for a later patch.
This bug had not been noticed earlier for two reasons:
1) Until recently, "gmbus" mode was disabled - all transfers actually
used "bit-bang" mode on GPIO port 5 (the "HDMI/DPD CTLDATA/CLK"
pair), at register 0x5024 (defined as GPIOF i915_reg.h).
Since this is the correct pair of pins for HDMI1, transfers succeed.
2) Even if gmbus mode is re-enabled, the first attempted transaction
will fail because it tries to use the wrong ("Reserved") pin pair.
However, the driver immediately falls back again to the bit-bang
method, which correctly uses GPIOF, so again, transfers succeed.
However, if gmbus mode is re-enabled and the GPIO fall-back mode is
disabled, then reading an attached monitor's EDID fail.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Split out gmbus_xfer_read/write() helper functions.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
With the recent set of gmbus fixes, this seems to work on my i855gm.
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Again, Valleyview modes these around, so make the mmio base more
explicit to consolidate the base address computations to one
HAS_PCH_SPLIT check.
v2: Fix up the PCH_SPLIT braino ... it actually works that way round.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
With the rework to merge the bit-banging fallback into the gmbus
i2c adapter we've gotten rid of the deadlock possibility that
originally lead to the disabling of this code.
This reverts the revert
commit 826c7e4147
Author: Jean Delvare <khali@linux-fr.org>
Date: Sat Jun 4 19:34:56 2011 +0000
Revert "drm/i915: Enable GMBUS for post-gen2 chipsets"
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=35572
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This way we can simplify the setup and teardown a bit.
Because we don't actually allocate anything anymore for the force_bit
case, we can now convert that into a boolean.
Also and the functionality supported by the bit-banging together with
what gmbus can do, so that this doesn't randomly change any more.
v2: Chris Wilson noticed that I've mixed up && and & ...
v3: Clarify an if block as suggested by Eugeni Dodonov.
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
... and directly call the newly exported i2c bit-banging functions.
The code is still pretty convoluted because we only set up the gpio
i2c stuff when actually falling back, resulting in more complexity
than necessary. This will be fixed up in the next patch.
v2: Use exported i2c_bit_algo vtable instead of exported functions.
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
When we set up the gpio fallback, we always have a 1:1 relationship
with an intel_gmbus. Exploit that to store all gpio related data in
there, too. This is a preparation step to merge the tw i2c adapters
controlling the same bus into one.
Just mundane code-munging in this patch.
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This way we can free up the bus->adaptor.algo_data pointer and make it
available for use with the bitbanging fallback algo.
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
gmbus_xfer with a single message (particularly a single message write) would
set Bus Cycle Select to 100b, the Gen Stop cycle, instead of 101b,
No Index, Stop cycle. This would not start single message i2c transactions.
Also, gmbus_xfer done: will disable the interface without checking if
it is idle. In the case of writes, there will be no wait on status or delay
to ensure the write starts and completes before the interface is turned off.
Fixed the former issue by using the same cycle selection as used in the
I2C_M_RD for the write case.
GMBUS_CYCLE_WAIT | (i + 1 == num ? GMBUS_CYCLE_STOP : 0)
Fixed the latter by waiting on GMBUS_ACTIVE to deassert before disable.
Note from the grumpy d-i-n maintainer: The first hunk that changes the
gmbus read path is just cosmetics to align the code with the write
path. I.e. the commit message above is slightly lying because the
first issue is _only_ with writes (and not simply "particularly").
Signed-off-by: Benson Leung <bleung@chromium.org>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Manually resolve the conflict between the new enum drm property
helpers in drm-next and the new "force-dvi" option that the "audio" output
property gained in drm-intel-next.
While resolving this conflict, switch the new drm_prop_enum_list to
use the newly introduced enum defines instead of magic values.
Conflicts:
drivers/gpu/drm/i915/intel_modes.c
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
GMBUS has several ports and each has it's own corresponding
I2C adpater. When multiple I2C adapters call gmbus_xfer() at
the same time there is a race condition in using the underlying
GMBUS controller. Fixing this by adding a mutex lock when calling
gmbus_xfer().
v2: Moved gmbus_mutex below intel_gmbus and added comments.
Rebased to drm-intel-next-queued.
Signed-off-by: Yufeng Shen <miletus@chromium.org>
[danvet: Shortened the gmbus_mutex comment a bit and add the patch
revision comment to the commit message.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
The first parameter should be "number of elements" and the second parameter
should be "element size".
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
A udelay value of 20 leads to an I2C bus running at only 25 kbps. I2C
devices can typically operate faster than this, 50 kbps should be fine
for all devices (and compliant devices can always stretch the clock if
needed.)
FWIW, the vast majority of framebuffer drivers set udelay to 10
already. So set it to 10 in DRM drivers too, this will make EDID block
reads faster. We might even lower the udelay value later if no problem
is reported.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Acked-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Cc: Keith Packard <keithp@keithp.com>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Revert commit 8f9a3f9b63. This fixes a
hang when loading the eeprom driver (see bug #35572.) GMBUS will be
re-enabled later, differently.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Reported-by: Marek Otahal <markotahal@gmail.com>
Tested-by: Yermandu Patapitafious <yermandu.dev@gmail.com>
Tested-by: Andrew Lutomirski <luto@mit.edu>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Once a NAK has been asserted by the slave, we need to reset the GMBUS
controller in order to continue. This is done by asserting the Software
Clear Interrupt bit and then clearing it again to restore operations.
If we don't clear the NAK, then all future GMBUS xfers will fail,
including DDC probes and EDID retrieval.
v2: Add some comments as suggested by Keith Packard.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=35781
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Keith Packard <keithp@keithp.com>
Tested-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: "Mengmeng Meng" <mengmeng.meng@intel.com>
With the recent SDVO fix, this is working on all the machines I have to
hand - except for an 845G.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Fix many small bugs in I2C adapter registration:
* Properly reject unsupported GPIO pin.
* Fix improper use of I2C_NAME_SIZE (which is the size of
i2c_client.name, not i2c_adapter.name.)
* Prefix adapter names with "i915" so that the user knows what the
I2C channel is connected to.
* Fix swapped characters in the string used to name the GPIO-based
adapter.
* Add missing comma in gmbus name table.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
As we use POSTING_READ to flush the write to the register before
proceeding, we do not care what the return value is and similar we do
not care for the read to be recorded whilst tracing register
read/writes.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
These registers are written very frequently, are timing sensitive, and
not particularly relevant to any debugging, so remove the tracepoints
from these.
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
In i2c GPIO fallback, index 6 is reserved for nothing.
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
There are several reported instances of GMBUS failing to successfully
read the EDID, so revert back to bit banging until the issue is
resolved.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=30371
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Besides a couple of bugs when writing more than a single byte along the
GMBUS, SDVO was completely failing whilst trying to use GMBUS, so use
bit banging instead.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Use the GMBUS interface rather than direct bit banging to grab the EDID
over DDC (and for other forms of auxiliary communication with external
display controllers). The hope is that this method will be much faster
and more reliable than bit banging for fetching EDIDs from buggy monitors
or through switches, though we still preserve the bit banging as a
fallback in case GMBUS fails.
Based on an original patch by Jesse Barnes.
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
The SDVO proxy i2c adapter wants to be able to use information stored in
the encoder, so pass that through intel_i2c rather than iterate over all
known encoders every time.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Remove our redundant udelay() as the timings are already handled by the
i2c-algo-bit controller.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
