This addresses deadlocks in these common cases in hierarchies containing
two switches:
- All involved ports are runtime suspended and they are unplugged. This
can happen easily if the drivers involved automatically enable runtime
PM (xHCI for example does that).
- System is suspended (e.g., closing the lid on a laptop) with a dock +
something else connected, and the dock is unplugged while suspended.
These cases lead to the following deadlock:
INFO: task irq/126-pciehp:198 blocked for more than 120 seconds.
irq/126-pciehp D 0 198 2 0x80000000
Call Trace:
schedule+0x2c/0x80
schedule_timeout+0x246/0x350
wait_for_completion+0xb7/0x140
kthread_stop+0x49/0x110
free_irq+0x32/0x70
pcie_shutdown_notification+0x2f/0x50
pciehp_remove+0x27/0x50
pcie_port_remove_service+0x36/0x50
device_release_driver+0x12/0x20
bus_remove_device+0xec/0x160
device_del+0x13b/0x350
device_unregister+0x1a/0x60
remove_iter+0x1e/0x30
device_for_each_child+0x56/0x90
pcie_port_device_remove+0x22/0x40
pcie_portdrv_remove+0x20/0x60
pci_device_remove+0x3e/0xc0
device_release_driver_internal+0x18c/0x250
device_release_driver+0x12/0x20
pci_stop_bus_device+0x6f/0x90
pci_stop_bus_device+0x31/0x90
pci_stop_and_remove_bus_device+0x12/0x20
pciehp_unconfigure_device+0x88/0x140
pciehp_disable_slot+0x6a/0x110
pciehp_handle_presence_or_link_change+0x263/0x400
pciehp_ist+0x1c9/0x1d0
irq_thread_fn+0x24/0x60
irq_thread+0xeb/0x190
kthread+0x120/0x140
INFO: task irq/190-pciehp:2288 blocked for more than 120 seconds.
irq/190-pciehp D 0 2288 2 0x80000000
Call Trace:
__schedule+0x2a2/0x880
schedule+0x2c/0x80
schedule_preempt_disabled+0xe/0x10
mutex_lock+0x2c/0x30
pci_lock_rescan_remove+0x15/0x20
pciehp_unconfigure_device+0x4d/0x140
pciehp_disable_slot+0x6a/0x110
pciehp_handle_presence_or_link_change+0x263/0x400
pciehp_ist+0x1c9/0x1d0
irq_thread_fn+0x24/0x60
irq_thread+0xeb/0x190
kthread+0x120/0x140
What happens here is that the whole hierarchy is runtime resumed and the
parent PCIe downstream port, which got the hot-remove event, starts
removing devices below it, taking pci_lock_rescan_remove() lock. When the
child PCIe port is runtime resumed it calls pciehp_check_presence() which
ends up calling pciehp_card_present() and pciehp_check_link_active(). Both
of these use pcie_capability_read_word(), which notices that the underlying
device is already gone and returns PCIBIOS_DEVICE_NOT_FOUND with the
capability value set to 0. When pciehp gets this value it thinks that its
child device is also hot-removed and schedules its IRQ thread to handle the
event.
The deadlock happens when the child's IRQ thread runs and tries to acquire
pci_lock_rescan_remove() which is already taken by the parent and the
parent waits for the child's IRQ thread to finish.
Prevent this from happening by checking the return value of
pcie_capability_read_word() and if it is PCIBIOS_DEVICE_NOT_FOUND stop
performing any hot-removal activities.
[bhelgaas: add common scenarios to commit log]
Link: https://lore.kernel.org/r/20191029170022.57528-2-mika.westerberg@linux.intel.com
Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
A sysfs request to enable or disable a PCIe hotplug slot should not
return before it has been carried out. That is sought to be achieved by
waiting until the controller's "pending_events" have been cleared.
However the IRQ thread pciehp_ist() clears the "pending_events" before
it acts on them. If pciehp_sysfs_enable_slot() / _disable_slot() happen
to check the "pending_events" after they have been cleared but while
pciehp_ist() is still running, the functions may return prematurely
with an incorrect return value.
Fix by introducing an "ist_running" flag which must be false before a sysfs
request is allowed to return.
Fixes: 32a8cef274 ("PCI: pciehp: Enable/disable exclusively from IRQ thread")
Link: https://lore.kernel.org/linux-pci/1562226638-54134-1-git-send-email-wangxiongfeng2@huawei.com
Link: https://lore.kernel.org/r/4174210466e27eb7e2243dd1d801d5f75baaffd8.1565345211.git.lukas@wunner.de
Reported-and-tested-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org # v4.19+
The PCIe spec doesn't mention "green LEDs" or "amber LEDs". Replace those
terms with "Power Indicator" and "Attention Indicator" so the comments
match the spec language. Comment changes only.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Remove pciehp_green_led_{on,off,blink}() and use pciehp_set_indicators()
instead, since the code is mostly the same.
[bhelgaas: drop set_power_indicator() wrapper to reduce the number of
interfaces]
Link: https://lore.kernel.org/r/20190903111021.1559-5-efremov@linux.com
Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Remove pciehp_set_attention_status() and use pciehp_set_indicators()
instead, since the code is mostly the same.
Link: https://lore.kernel.org/r/20190903111021.1559-4-efremov@linux.com
Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Add pciehp_set_indicators() to set power and attention indicators with a
single register write.
This is a minor optimization because we frequently set both indicators and
this can do it with a single command. It also reduces the number of
interfaces related to the indicators and makes them more discoverable
because callers use the PCI_EXP_SLTCTL_ATTN_IND_* and
PCI_EXP_SLTCTL_PWR_IND_* definitions directly.
[bhelgaas: extend commit log, s/PCI_EXP_SLTCTL_.*_IND_NONE/INDICATOR_NOOP/
so they don't look like things defined by the spec, add function doc, mask
commands to make it obvious we only send valid commands
(pcie_do_write_cmd() does mask it, but requires more effort to verify)]
Link: https://lore.kernel.org/r/20190903111021.1559-2-efremov@linux.com
Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
MY_NAME is only used once and offers no benefit, so remove it.
Link: https://lore.kernel.org/lkml/20190509141456.223614-11-helgaas@kernel.org
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Replace the last uses of dbg() with the equivalent pr_debug(), then remove
unused dbg(), err(), info(), and warn() wrappers.
Link: https://lore.kernel.org/lkml/20190509141456.223614-9-helgaas@kernel.org
Signed-off-by: Frederick Lawler <fred@fredlawl.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Log messages with pci_dev, not pcie_device. Factor out common message
prefixes with dev_fmt().
Example output change:
- pciehp 0000:00:06.0:pcie004: Slot(0) Powering on due to button press
+ pcieport 0000:00:06.0: pciehp: Slot(0) Powering on due to button press
Link: https://lore.kernel.org/lkml/20190509141456.223614-8-helgaas@kernel.org
Signed-off-by: Frederick Lawler <fred@fredlawl.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Previously pciehp debug messages were enabled by the pciehp_debug module
parameter, e.g., by booting with this kernel command line option:
pciehp.pciehp_debug=1
Convert this mechanism to use the generic dynamic debug (dyndbg) feature.
After this commit, pciehp debug messages are enabled by building the kernel
with CONFIG_DYNAMIC_DEBUG=y and booting with this command line option:
dyndbg="file pciehp* +p"
The dyndbg facility is much more flexible: messages can be enabled at boot-
or run-time based on the file name, function name, line number, message
test, etc. See Documentation/admin-guide/dynamic-debug-howto.rst for more
details.
Link: https://lore.kernel.org/lkml/20190509141456.223614-7-helgaas@kernel.org
Signed-off-by: Frederick Lawler <fred@fredlawl.com>
[bhelgaas: commit log, comment, remove pciehp_debug parameter]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
When PCIe hotplug port is transitioned into D3hot, the link to the
downstream component will go down. If hotplug interrupt generation is
enabled when that happens, it will trigger immediately, waking up the
system and bringing the link back up.
To prevent this, disable hotplug interrupt generation when system suspend
is entered. This does not prevent wakeup from low power states according
to PCIe 4.0 spec section 6.7.3.4:
Software enables a hot-plug event to generate a wakeup event by
enabling software notification of the event as described in Section
6.7.3.1. Note that in order for software to disable interrupt generation
while keeping wakeup generation enabled, the Hot-Plug Interrupt Enable
bit must be cleared.
So as long as we have set the slot event mask accordingly, wakeup should
work even if slot interrupt is disabled. The port should trigger wake and
then send PME to the root port when the PCIe hierarchy is brought back up.
Limit this to systems using native PME mechanism to make sure older Apple
systems depending on commit e3354628c376 ("PCI: pciehp: Support interrupts
sent from D3hot") still continue working.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The spec has timing requirements when waiting for a link to become active
after a conventional reset. Implement those hard delays when waiting for
an active link so pciehp and dpc drivers don't need to duplicate this.
For devices that don't support data link layer active reporting, wait the
fixed time recommended by the PCIe spec.
Signed-off-by: Keith Busch <keith.busch@intel.com>
[bhelgaas: changelog]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Sinan Kaya <okaya@kernel.org>
When the PCI hotplug core and its first user, cpqphp, were introduced in
February 2002 with historic commit a8a2069f432c, cpqphp allocated a slot
struct for its internal use plus a hotplug_slot struct to be registered
with the hotplug core and linked the two with pointers:
https://git.kernel.org/tglx/history/c/a8a2069f432c
Nowadays, the predominant pattern in the tree is to embed ("subclass")
such structures in one another and cast to the containing struct with
container_of(). But it wasn't until July 2002 that container_of() was
introduced with historic commit ec4f214232cf:
https://git.kernel.org/tglx/history/c/ec4f214232cf
pnv_php, introduced in 2016, did the right thing and embedded struct
hotplug_slot in its internal struct pnv_php_slot, but all other drivers
cargo-culted cpqphp's design and linked separate structs with pointers.
Embedding structs is preferrable to linking them with pointers because
it requires fewer allocations, thereby reducing overhead and simplifying
error paths. Casting an embedded struct to the containing struct
becomes a cheap subtraction rather than a dereference. And having fewer
pointers reduces the risk of them pointing nowhere either accidentally
or due to an attack.
Convert all drivers to embed struct hotplug_slot in their internal slot
struct. The "private" pointer in struct hotplug_slot thereby becomes
unused, so drop it.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com> # drivers/pci/hotplug/rpa*
Acked-by: Sebastian Ott <sebott@linux.ibm.com> # drivers/pci/hotplug/s390*
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> # drivers/platform/x86
Cc: Len Brown <lenb@kernel.org>
Cc: Scott Murray <scott@spiteful.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Oliver OHalloran <oliveroh@au1.ibm.com>
Cc: Gavin Shan <gwshan@linux.vnet.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Corentin Chary <corentin.chary@gmail.com>
Cc: Darren Hart <dvhart@infradead.org>
The members in pciehp's controller struct are arranged in a seemingly
arbitrary order and have grown to an amount that I no longer consider
easily graspable by contributors.
Sort the members into 5 rubrics:
* Slot Capabilities register and quirks
* Slot Control register access
* Slot Status register event handling
* state machine
* hotplug core interface
Obviously, this is just my personal bikeshed color and if anyone has a
better idea, please come forward. Any ordering will do as long as the
information is presented in a manageable manner.
No functional change intended.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Of the members which were just moved from pciehp's slot struct to the
controller struct, rename "lock" to "state_lock" and rename "work" to
"button_work" for clarity. Perform the rename separately to the
unification of the two structs per Sinan's request.
No functional change intended.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Sinan Kaya <okaya@kernel.org>
pciehp was originally introduced together with shpchp in a single
commit, c16b4b14d980 ("PCI Hotplug: Add SHPC and PCI Express hot-plug
drivers"):
https://git.kernel.org/tglx/history/c/c16b4b14d980
shpchp supports up to 31 slots per controller, hence uses separate slot
and controller structs. pciehp has a 1:1 relationship between slot and
controller and therefore never required this separation. Nevertheless,
because much of the code had been copy-pasted between the two drivers,
pciehp likewise uses separate structs to this very day.
The artificial separation of data structures adds unnecessary complexity
and bloat to pciehp and requires constantly chasing pointers at runtime.
Simplify the driver by merging struct slot into struct controller.
Merge the slot constructor pcie_init_slot() and the destructor
pcie_cleanup_slot() into the controller counterparts.
No functional change intended.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
The WiGig Bus Extension (WBE) specification allows tunneling PCIe over
IEEE 802.11. A product implementing this spec is the wil6210 from
Wilocity (now part of Qualcomm Atheros). It integrates a PCIe switch
with a wireless network adapter:
00.0-+ [1ae9:0101] Upstream Port
+-00.0-+ [1ae9:0200] Downstream Port
| +-00.0 [168c:0034] Atheros AR9462 Wireless Network Adapter
+-02.0 [1ae9:0201] Downstream Port
+-03.0 [1ae9:0201] Downstream Port
Wirelessly attached devices presumably appear below the hotplug ports
with device ID [1ae9:0201]. Oddly, the Downstream Port [1ae9:0200]
leading to the wireless network adapter is likewise Hotplug Capable,
but has its Presence Detect State bit hardwired to zero. Even if the
Link Active bit is set, Presence Detect is zero, so this cannot be
caused by in-band presence detection but only by broken hardware.
pciehp assumes an empty slot if Presence Detect State is zero,
regardless of Link Active being one. Consequently, up until v4.18 it
removes the wireless network adapter in pciehp_resume(). From v4.19 it
already does so in pciehp_probe().
Be lenient towards broken hardware and assume the slot is occupied if
Link Active is set: Introduce pciehp_card_present_or_link_active()
and use it in lieu of pciehp_get_adapter_status() everywhere, except
in pciehp_handle_presence_or_link_change() whose log messages depend
on which of Presence Detect State or Link Active is set.
Remove the Presence Detect State check from __pciehp_enable_slot()
because it is only called if either of Presence Detect State or Link
Active is set.
Caution: There is a possibility that broken hardware exists which has
working Presence Detect but hardwires Link Active to one. On such
hardware the slot will now incorrectly be considered always occupied.
If such hardware is discovered, this commit can be rolled back and a
quirk can be added which sets is_hotplug_bridge = 0 for [1ae9:0200].
Link: https://bugzilla.kernel.org/show_bug.cgi?id=200839
Reported-and-tested-by: David Yang <mmyangfl@gmail.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Rajat Jain <rajatja@google.com>
Cc: Ashok Raj <ashok.raj@intel.com>
pciehp's ->enable_slot, ->disable_slot, ->get_attention_status and
->reset_slot callbacks are currently implemented by wrapper functions
that do nothing else but call down to a backend function. The backends
are not called from anywhere else, so drop the wrappers and use the
backends directly as callbacks, thereby shaving off a few lines of
unnecessary code.
No functional change intended.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Drop the following includes from pciehp source files which no longer use
any of the included symbols:
* <linux/sched/signal.h> in pciehp.h
<linux/signal.h> in pciehp_hpc.c
Added by commit de25968cc8 ("fix more missing includes") to
accommodate for a call to signal_pending().
The call was removed by commit 262303fe32 ("pciehp: fix wait command
completion").
* <linux/interrupt.h> in pciehp_core.c
Added by historic commit f308a2dfbe63 ("PCI: add PCI Express Port Bus
Driver subsystem") to accommodate for a call to free_irq():
https://git.kernel.org/tglx/history/c/f308a2dfbe63
The call was removed by commit 407f452b05 ("pciehp: remove
unnecessary free_irq").
* <linux/time.h> in pciehp_core.c and pciehp_hpc.c
Added by commit 34d03419f0 ("PCIEHP: Add Electro Mechanical
Interlock (EMI) support to the PCIE hotplug driver."),
which was reverted by commit bd3d99c170 ("PCI: Remove untested
Electromechanical Interlock (EMI) support in pciehp.").
* <linux/module.h> in pciehp_ctrl.c, pciehp_hpc.c and pciehp_pci.c
Added by historic commit c16b4b14d980 ("PCI Hotplug: Add SHPC and PCI
Express hot-plug drivers"):
https://git.kernel.org/tglx/history/c/c16b4b14d980
Module-related symbols were neither used back then in those files,
nor are they used today.
* <linux/slab.h> in pciehp_ctrl.c
Added by commit 5a0e3ad6af ("include cleanup: Update gfp.h and
slab.h includes to prepare for breaking implicit slab.h inclusion from
percpu.h") to accommodate for calls to kmalloc().
The calls were removed by commit 0e94916e60 ("PCI: pciehp: Handle
events synchronously").
* "../pci.h" in pciehp_ctrl.c
Added by historic commit 67f4660b72f2 ("PCI: ASPM patch for") to
accommodate for usage of the global variable pcie_mch_quirk:
https://git.kernel.org/tglx/history/c/67f4660b72f2
The global variable was removed by commit 0ba379ec0f ("PCI: Simplify
hotplug mch quirk").
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
When removing PCI devices below a hotplug bridge, pciehp marks them as
disconnected if the card is no longer present in the slot or it quiesces
them if the card is still present (by disabling INTx interrupts, bus
mastering and SERR# reporting).
To detect whether the card is still present, pciehp checks the Presence
Detect State bit in the Slot Status register. The problem with this
approach is that even if the card is present, the link to it may be
down, and it that case it would be better to mark the devices as
disconnected instead of trying to quiesce them. Moreover, if the card
in the slot was quickly replaced by another one, the Presence Detect
State bit would be set, yet trying to quiesce the new card's devices
would be wrong and the correct thing to do is to mark the previous
card's devices as disconnected.
Instead of looking at the Presence Detect State bit, it is better to
differentiate whether the card was surprise removed versus safely
removed (via sysfs or an Attention Button press). On surprise removal,
the devices should be marked as disconnected, whereas on safe removal it
is correct to quiesce the devices.
The knowledge whether a surprise removal or a safe removal is at hand
does exist further up in the call stack: A surprise removal is
initiated by pciehp_handle_presence_or_link_change(), a safe removal by
pciehp_handle_disable_request().
Pass that information down to pciehp_unconfigure_device() and use it in
lieu of the Presence Detect State bit. While there, add kernel-doc to
pciehp_unconfigure_device() and pciehp_configure_device().
Tested-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Keith Busch <keith.busch@intel.com>
If a hotplug port is able to send an interrupt, one would naively assume
that it is accessible at that moment. After all, if it wouldn't be
accessible, i.e. if its parent is in D3hot and the link to the hotplug
port is thus down, how should an interrupt come through?
It turns out that assumption is wrong at least for Thunderbolt: Even
though its parents are in D3hot, a Thunderbolt hotplug port is able to
signal interrupts. Because the port's config space is inaccessible and
resuming the parents may sleep, the hard IRQ handler has to defer
runtime resuming the parents and reading the Slot Status register to the
IRQ thread.
If the hotplug port uses a level-triggered INTx interrupt, it needs to
be masked until the IRQ thread has cleared the signaled events. For
simplicity, this commit also masks edge-triggered MSI/MSI-X interrupts.
Note that if the interrupt is shared (which can only happen for INTx),
other devices are starved from receiving interrupts until the IRQ thread
is scheduled, has runtime resumed the hotplug port's parents and has
read and cleared the Slot Status register.
That delay is dominated by the 10 ms D3hot->D0 transition time of each
parent port. The worst case is a Thunderbolt downstream port at the
end of a daisy chain: There may be up to six Thunderbolt controllers
in-between it and the root port, each comprising an upstream and
downstream port, plus its own upstream port. That's 13 x 10 = 130 ms.
Possible mitigations are polling the interrupt while it's disabled or
reducing the d3_delay of Thunderbolt ports if possible.
Open code masking of the interrupt instead of requesting it with the
IRQF_ONESHOT flag to minimize the period during which it is masked.
(IRQF_ONESHOT unmasks the IRQ only after the IRQ thread has finished.)
PCIe r4.0 sec 6.7.3.4 states that "If wake generation is required by the
associated form factor specification, a hotplug capable Downstream Port
must support generation of a wakeup event (using the PME mechanism) on
hotplug events that occur when the system is in a sleep state or the
Port is in device state D1, D2, or D3Hot."
This would seem to imply that PME needs to be enabled on the hotplug
port when it is runtime suspended. pci_enable_wake() currently doesn't
enable PME on bridges, it may be necessary to add an exemption for
hotplug bridges there. On "Light Ridge" Thunderbolt controllers, the
PME_Status bit is not set when an interrupt occurs while the hotplug
port is in D3hot, even if PME is enabled. (I've tested this on a Mac
and we hardcode the OSC_PCI_EXPRESS_PME_CONTROL bit to 0 on Macs in
negotiate_os_control(), modifying it to 1 didn't change the behavior.)
(Side note: Section 6.7.3.4 also states that "PME and Hot-Plug Event
interrupts (when both are implemented) always share the same MSI or
MSI-X vector". That would only seem to apply to Root Ports, however
the section never mentions Root Ports, only Downstream Ports. This is
explained in the definition of "Downstream Port" in the "Terms and
Acronyms" section of the PCIe Base Spec: "The Ports on a Switch that
are not the Upstream Port are Downstream Ports. All Ports on a Root
Complex are Downstream Ports.")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Thunderbolt hotplug ports that were occupied before system sleep resume
with their downstream link in "off" state. Only after the Thunderbolt
controller has reestablished the PCIe tunnels does the link go up.
As a result, a spurious Presence Detect Changed and/or Data Link Layer
State Changed event occurs.
The events are not immediately acted upon because tunnel reestablishment
happens in the ->resume_noirq phase, when interrupts are still disabled.
Also, notification of events may initially be disabled in the Slot
Control register when coming out of system sleep and is reenabled in the
->resume_noirq phase through:
pci_pm_resume_noirq()
pci_pm_default_resume_early()
pci_restore_state()
pci_restore_pcie_state()
It is not guaranteed that the events are acted upon at all: PCIe r4.0,
sec 6.7.3.4 says that "a port may optionally send an MSI when there are
hot-plug events that occur while interrupt generation is disabled, and
interrupt generation is subsequently enabled." Note the "optionally".
If an MSI is sent, pciehp will gratuitously turn the slot off and back
on once the ->resume_early phase has commenced.
If an MSI is not sent, the extant, unacknowledged events in the Slot
Status register will prevent future notification of presence or link
changes.
Commit 13c65840fe ("PCI: pciehp: Clear Presence Detect and Data Link
Layer Status Changed on resume") fixed the latter by clearing the events
in the ->resume phase. Move this to the ->resume_noirq phase to also
fix the gratuitous disable/enablement of the slot.
The commit further restored the Slot Control register in the ->resume
phase, but that's dispensable because as shown above it's already been
done in the ->resume_noirq phase.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
The ->reset_slot callback introduced by commits:
2e35afaefe ("PCI: pciehp: Add reset_slot() method") and
06a8d89af5 ("PCI: pciehp: Disable link notification across slot reset")
disables notification of Presence Detect Changed and Data Link Layer
State Changed events for the duration of a secondary bus reset.
However a bus reset not only triggers these events, but may also clear
the Presence Detect State bit in the Slot Status register and the Data
Link Layer Link Active bit in the Link Status register momentarily.
According to Sinan Kaya:
"I know for a fact that bus reset clears the Data Link Layer Active bit
as soon as link goes down. It gets set again following link up.
Presence detect depends on the HW implementation. QDT root ports
don't change presence detect for instance since nobody actually
removed the card. If an implementation supports in-band presence
detect, the answer is yes. As soon as the link goes down, presence
detect bit will get cleared until recovery."
https://lkml.kernel.org/r/42e72f83-3b24-f7ef-e5bc-290fae99259a@codeaurora.org
In-band presence detect is also covered in Table 4-15 in PCIe r4.0,
sec 4.2.6.
pciehp should therefore ensure that any parts of the driver that access
those bits do not run concurrently to a bus reset. The only precaution
the commits took to that effect was to halt interrupt polling. They
made no effort to drain the slot workqueue, cancel an outstanding
Attention Button work, or block slot enable/disable requests via sysfs
and in the ->probe hook.
Now that pciehp is converted to enable/disable the slot exclusively from
the IRQ thread, the only places accessing the two above-mentioned bits
are the IRQ thread and the ->probe hook. Add locking to serialize them
with a bus reset. This obviates the need to halt interrupt polling.
Do not add locking to the ->get_adapter_status sysfs callback to afford
users unfettered access to that bit. Use an rw_semaphore in lieu of a
regular mutex to allow parallel execution of the non-reset code paths
accessing the critical bits, i.e. the IRQ thread and the ->probe hook.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Rajat Jain <rajatja@google.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Sinan Kaya <okaya@kernel.org>
A hotplug port's Slot Status register does not count how often each type
of event occurred, it only records the fact *that* an event has occurred.
Previously pciehp queued a work item for each event. But if it missed
an event, e.g. removal of a card in-between two back-to-back insertions,
it queued up the wrong work item or no work item at all. Commit
fad214b0aa ("PCI: pciehp: Process all hotplug events before looking
for new ones") sought to improve the situation by shrinking the window
during which events may be missed.
But Stefan Roese reports unbalanced Card present and Link Up events,
suggesting that we're still missing events if they occur very rapidly.
Bjorn Helgaas responds that he considers pciehp's event handling
"baroque" and calls for its simplification and rationalization:
https://lkml.kernel.org/r/20180202192045.GA53759@bhelgaas-glaptop.roam.corp.google.com
It gets worse once a hotplug port is runtime suspended: The port can
signal an interrupt while it and its parents are in D3hot, i.e. while
it is inaccessible. By the time we've runtime resumed all parents to D0
and read the port's Slot Status register, we may have missed an arbitrary
number of events. Event handling therefore needs to be reworked to
become resilient to missed events.
Assume that a Presence Detect Changed event has occurred.
Consider the following truth table:
- Slot is in OFF_STATE and is currently empty. => Do nothing.
(The event is trailing a Link Down or we've
missed an insertion and subsequent removal.)
- Slot is in OFF_STATE and is currently occupied. => Turn the slot on.
- Slot is in ON_STATE and is currently empty. => Turn the slot off.
- Slot is in ON_STATE and is currently occupied. => Turn the slot off,
(Be cautious and assume the card in then back on.
the slot isn't the same as before.)
This leads to the following simple algorithm:
1 If the slot is in ON_STATE, turn it off unconditionally.
2 If the slot is currently occupied, turn it on.
Because those actions are now carried out synchronously, rather than by
scheduled work items, pciehp reacts to the *current* situation and
missed events no longer matter.
Data Link Layer State Changed events can be handled identically to
Presence Detect Changed events. Note that in the above truth table,
a Link Up trailing a Card present event didn't have to be accounted for:
It is filtered out by pciehp_check_link_status().
As for Attention Button Pressed events, PCIe r4.0, sec 6.7.1.5 says:
"Once the Power Indicator begins blinking, a 5-second abort interval
exists during which a second depression of the Attention Button cancels
the operation." In other words, the user can only expect the system to
react to a button press after it starts blinking. Missed button presses
that occur in-between are irrelevant.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Mayurkumar Patel <mayurkumar.patel@intel.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
No callers of pciehp_enable/disable_slot() outside of pciehp_ctrl.c
remain, so declare the functions static. For now this requires forward
declarations. Those can be eliminated by reshuffling functions once the
ongoing effort to refactor the driver has settled.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Previously slot enablement and disablement could happen concurrently.
But now it's under the exclusive control of the IRQ thread, rendering
the locking obsolete. Drop it.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Besides the IRQ thread, there are several other places in the driver
which enable or disable the slot:
- pciehp_probe() enables the slot if it's occupied and the pciehp_force
module parameter is used.
- pciehp_resume() enables or disables the slot after system sleep.
- pciehp_queue_pushbutton_work() enables or disables the slot after the
5 second delay following an Attention Button press.
- pciehp_sysfs_enable_slot() and pciehp_sysfs_disable_slot() enable or
disable the slot on sysfs write.
This requires locking and complicates pciehp's state machine.
A simplification can be achieved by enabling and disabling the slot
exclusively from the IRQ thread.
Amend the functions listed above to request slot enable/disablement from
the IRQ thread by either synthesizing a Presence Detect Changed event or,
in the case of a disable user request (via sysfs or an Attention Button
press), submitting a newly introduced force disable request. The latter
is needed because the slot shall be forced off despite being occupied.
For this force disable request, avoid colliding with Slot Status register
bits by using a bit number greater than 16.
For synchronous execution of requests (on sysfs write), wait for the
request to finish and retrieve the result. There can only ever be one
sysfs write in flight due to the locking in kernfs_fop_write(), hence
there is no risk of returning the result of a different sysfs request to
user space.
The POWERON_STATE and POWEROFF_STATE is now no longer entered by the
above-listed functions, but solely by the IRQ thread when it begins a
power transition. Afterwards, it moves to STATIC_STATE. The same
applies to canceling the Attention Button work, it likewise becomes an
IRQ thread only operation.
An immediate consequence is that the POWERON_STATE and POWEROFF_STATE is
never observed by the IRQ thread itself, only by functions called in a
different context, such as pciehp_sysfs_enable_slot(). So remove
handling of these states from pciehp_handle_button_press() and
pciehp_handle_link_change() which are exclusively called from the IRQ
thread.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
handle_button_press_event() currently determines whether the slot has
been turned on or off by looking at the Power Controller Control bit in
the Slot Control register. This assumes that an attention button
implies presence of a power controller even though that's not mandated
by the spec. Moreover the Power Controller Control bit is unreliable
when a power fault occurs (PCIe r4.0, sec 6.7.1.8). This issue has
existed since the driver was introduced in 2004.
Fix by replacing STATIC_STATE with ON_STATE and OFF_STATE and tracking
whether the slot has been turned on or off. This is also a required
ingredient to make pciehp resilient to missed events, which is the
object of an upcoming commit.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Previously the slot workqueue was used to handle events and enable or
disable the slot. That's no longer the case as those tasks are done
synchronously in the IRQ thread. The slot workqueue is thus merely used
to handle a button press after the 5 second delay and only one such work
item may be in flight at any given time. A separate workqueue isn't
necessary for this simple task, so use the system workqueue instead.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Up until now, pciehp's IRQ handler schedules a work item for each event,
which in turn schedules a work item to enable or disable the slot. This
double indirection was necessary because sleeping wasn't allowed in the
IRQ handler.
However it is now that pciehp has been converted to threaded IRQ handling
and polling, so handle events synchronously in pciehp_ist() and remove
the work item infrastructure (with the exception of work items to handle
a button press after the 5 second delay).
For link or presence change events, move the register read to determine
the current link or presence state behind acquisition of the slot lock
to prevent it from becoming stale while the lock is contended.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
We've just converted pciehp to threaded IRQ handling, but still cannot
sleep in pciehp_ist() because the function is also called in poll mode,
which runs in softirq context (from a timer).
Convert poll mode to a kthread so that pciehp_ist() always runs in task
context.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
pciehp's IRQ handler queues up a work item for each event signaled by
the hardware. A more modern alternative is to let a long running
kthread service the events. The IRQ handler's sole job is then to check
whether the IRQ originated from the device in question, acknowledge its
receipt to the hardware to quiesce the interrupt and wake up the kthread.
One benefit is reduced latency to handle the IRQ, which is a necessity
for realtime environments. Another benefit is that we can make pciehp
simpler and more robust by handling events synchronously in process
context, rather than asynchronously by queueing up work items. pciehp's
usage of work items is a historic artifact, it predates the introduction
of threaded IRQ handlers by two years. (The former was introduced in
2007 with commit 5d386e1ac4 ("pciehp: Event handling rework"), the
latter in 2009 with commit 3aa551c9b4 ("genirq: add threaded interrupt
handler support").)
Convert pciehp to threaded IRQ handling by retrieving the pending events
in pciehp_isr(), saving them for later consumption by the thread handler
pciehp_ist() and clearing them in the Slot Status register.
By clearing the Slot Status (and thereby acknowledging the events) in
pciehp_isr(), we can avoid requesting the IRQ with IRQF_ONESHOT, which
would have the unpleasant side effect of starving devices sharing the
IRQ until pciehp_ist() has finished.
pciehp_isr() does not count how many times each event occurred, but
merely records the fact *that* an event occurred. If the same event
occurs a second time before pciehp_ist() is woken, that second event
will not be recorded separately, which is problematic according to
commit fad214b0aa ("PCI: pciehp: Process all hotplug events before
looking for new ones") because we may miss removal of a card in-between
two back-to-back insertions. We're about to make pciehp_ist() resilient
to missed events. The present commit regresses the driver's behavior
temporarily in order to separate the changes into reviewable chunks.
This doesn't affect regular slow-motion hotplug, only plug-unplug-plug
operations that happen in a timespan shorter than wakeup of the IRQ
thread.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Mayurkumar Patel <mayurkumar.patel@intel.com>
Cc: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Document the driver's data structures to lower the barrier to entry for
contributors.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Since commit 0f4bd8014d ("PCI: hotplug: Drop checking of PCI_BRIDGE_
CONTROL in *_unconfigure_device()"), pciehp_unconfigure_device() can no
longer fail, so declare it and its sole caller remove_board() void, in
keeping with the usual kernel pattern that enablement can fail, but
disablement cannot. No functional change intended.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
When pciehp is unbound (e.g. on unplug of a Thunderbolt device), the
hotplug_slot struct is deregistered and thus freed before freeing the
IRQ. The IRQ handler and the work items it schedules print the slot
name referenced from the freed structure in various informational and
debug log messages, each time resulting in a quadruple dereference of
freed pointers (hotplug_slot -> pci_slot -> kobject -> name).
At best the slot name is logged as "(null)", at worst kernel memory is
exposed in logs or the driver crashes:
pciehp 0000:10:00.0:pcie204: Slot((null)): Card not present
An attacker may provoke the bug by unplugging multiple devices on a
Thunderbolt daisy chain at once. Unplugging can also be simulated by
powering down slots via sysfs. The bug is particularly easy to trigger
in poll mode.
It has been present since the driver's introduction in 2004:
https://git.kernel.org/tglx/history/c/c16b4b14d980
Fix by rearranging teardown such that the IRQ is freed first. Run the
work items queued by the IRQ handler to completion before freeing the
hotplug_slot struct by draining the work queue from the ->release_slot
callback which is invoked by pci_hp_deregister().
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org # v2.6.4
After a suspend/resume cycle the Presence Detect or Data Link Layer Status
Changed bits might be set. If we don't clear them those events will not
fire anymore and nothing happens for instance when a device is now
hot-unplugged.
Fix this by clearing those bits in a newly introduced function
pcie_reenable_notification(). This should be fine because immediately
after, we check if the adapter is still present by reading directly from
the status register.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: stable@vger.kernel.org
pcieport_if.h contained the interfaces to register port service driver,
e.g., pcie_port_service_register(). portdrv.h contained internal data
structures of the port driver.
I don't think it's worth keeping those files separate, since both headers
and their users are all inside the PCI core.
Merge pcieport_if.h directly in drivers/pci/pcie/portdrv.h and update the
users to include that instead.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Move pcieport_if.h from include/linux to drivers/pci/pcie/pcieport_if.h
because the interfaces there are only used by the PCI core.
Replace all uses of #include<linux/pcieport_if.h> with relative paths to
the new file location, e.g., #include "../pcieport_if.h"
Signed-off-by: Frederick Lawler <fred@fredlawl.com>
Signed-off-by: Bjorn Helgaas <helgaas@kernel.org>
Add SPDX GPL-2.0+ to all PCI files that specified the GPL and allowed
either GPL version 2 or any later version.
Remove the boilerplate GPL version 2 or later language, relying on the
assertion in b24413180f ("License cleanup: add SPDX GPL-2.0 license
identifier to files with no license") that the SPDX identifier may be used
instead of the full boilerplate text.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fix up affected files that include this signal functionality via sched.h.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
PCIe hotplug supports optional Attention and Power Indicators, which are
used internally by pciehp. Users can't control the Power Indicator, but
they can control the Attention Indicator by writing to a sysfs "attention"
file.
The Slot Control register has two bits for each indicator, and the PCIe
spec defines the encodings for each as (Reserved/On/Blinking/Off). For
sysfs "attention" writes, pciehp_set_attention_status() maps into these
encodings, so the only useful write values are 0 (Off), 1 (On), and 2
(Blinking).
However, some platforms use all four bits for platform-specific indicators,
and they need to allow direct user control of them while preventing pciehp
from using them at all.
Add a "hotplug_user_indicators" flag to the pci_dev structure. When set,
pciehp does not use either the Attention Indicator or the Power Indicator,
and the low four bits (values 0x0 - 0xf) of sysfs "attention" write values
are written directly to the Attention Indicator Control and Power Indicator
Control fields.
[bhelgaas: changelog, rename flag and accessors to s/attention/indicator/]
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Fix all whitespace issues (missing or needed whitespace) in all files in
drivers/pci. Code is compiled with allyesconfig before and after code
changes and objects are recorded and checked with objdiff and they are not
changed after this commit.
Signed-off-by: Bogicevic Sasa <brutallesale@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
We queued interrupt events for the MRL being opened or closed, but the code
in interrupt_event_handler() that handles these events ignored them.
Stop enabling MRL interrupts and remove the ignored events.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
The list of interrupt events (INT_BUTTON_IGNORE, INT_PRESENCE_ON, etc.) was
copied from other hotplug drivers, but pciehp doesn't use them all.
Remove the interrupt events that aren't used by pciehp.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
The pciehp_handle_*() functions (pciehp_handle_attention_button(), etc.)
only contain a line or two of useful code, so it's clumsy to put
them in separate functions. All they so is add an event to a work queue,
and it's clearer to see that directly in the ISR.
Inline them directly into pcie_isr(). No functional change.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rajat Jain <rajatja@google.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Jarod Wilson reports that ExpressCard hotplug doesn't work on HP ZBook G2.
The problem turns out to be the ACPI-based "slot detection" code called
from pciehp_probe() which uses questionable heuristics based on what ACPI
objects are present for the PCIe port device to figure out whether to
register a hotplug slot for that port.
That code is used if there is at least one PCIe port having an ACPI device
configuration object related to hotplug (such as _EJ0 or _RMV), and the
Thunderbolt port on the ZBook has _RMV. Of course, Thunderbolt and PCIe
native hotplug need not be mutually exclusive (as they aren't on the
ZBook), so that rule is simply incorrect.
Moreover, the ACPI-based "slot detection" check does not add any value if
pciehp_probe() is called at all and the service type of the device object
it has been called for is PCIE_PORT_SERVICE_HP, because PCIe hotplug
services are only registered if the _OSC handshake in acpi_pci_root_add()
allows the kernel to control the PCIe native hotplug feature. No more
checks need to be carried out to decide whether or not to register a native
PCIe hotlug slot in that case.
For the above reasons, make pciehp_probe() check if it has been called for
the right service type and drop the pointless ACPI-based "slot detection"
check from it. Also remove the entire code whose only user is that check
(the entire pciehp_acpi.c file goes away as a result) and drop function
headers related to it from the internal pciehp header file.
Link: http://lkml.kernel.org/r/1431632038-39917-1-git-send-email-jarod@redhat.com
Link: https://bugzilla.kernel.org/show_bug.cgi?id=98581
Reported-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jarod Wilson <jarod@redhat.com>
Tested-by: Jarod Wilson <jarod@redhat.com>
4283c70e91 ("PCI: pciehp: Make pcie_wait_cmd() self-contained") added
a cache of the most recent command written to the Slot Control register.
This register is only 16 bits wide, but the cache ("slot_ctrl") is 32 bits.
Reduce slot_ctrl to a u16 so it matches the register size. No functional
change.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
"no_cmd_complete" is only used once, and it duplicates read-only
information we already have in the cached Slot Capabilities value.
Remove the field and use the existing macro NO_CMD_CMPL() instead.
[bhelgaas: changelog]
Signed-off-by: Rajat Jain <rajatxjain@gmail.com>
Signed-off-by: Rajat Jain <rajatjain@juniper.net>
Signed-off-by: Guenter Roeck <groeck@juniper.net>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
If we issue a hotplug command, go do something else, then come back and
wait for the command to complete, we don't have to wait the whole timeout
period, because some of it elapsed while we were doing something else.
Keep track of the time we issued the command, and wait only until the
timeout period from that point has elapsed.
For controllers with errata like Intel CF118, we previously timed out
before issuing the second hotplug command:
At time T1 (during boot):
- Write DLLSCE, ABPE, PDCE, etc. to Slot Control
At time T2 (hotplug event):
- Wait for command completion (CC) in Slot Status
- Timeout at T2 + 1 second because CC is never set in Slot Status
- Write PCC, PIC, etc. to Slot Control
With this change, we wait until T1 + 1 second instead of T2 + 1 second.
If the hotplug event is more than 1 second after the boot-time
initialization, we won't wait for the timeout at all.
We still emit a "Timeout on hotplug command" message if it timed out; we
should see this on the first hotplug event on every controller with this
erratum, as well as on real errors on controllers without the erratum.
Link: http://www.intel.com/content/www/us/en/processors/xeon/xeon-e7-v2-spec-update.html
Tested-by: Rajat Jain <rajatxjain@gmail.com> (IDT 807a controller)
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
pcie_wait_cmd() waits for the controller to finish a hotplug command. Move
the associated logic (to determine whether waiting is required and whether
we're using interrupts or polling) from pcie_write_cmd() to
pcie_wait_cmd().
No functional change.
Tested-by: Rajat Jain <rajatxjain@gmail.com> (IDT 807a controller)
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
