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  1. 09 6月, 2015 1 次提交
    • A
      PCI: pciehp: Wait for hotplug command completion where necessary · a5dd4b4b
      由 Alex Williamson 提交于 
      The commit referenced below deferred waiting for command completion until
the start of the next command, allowing hardware to do the latching
asynchronously.  Unfortunately, being ready to accept a new command is the
only indication we have that the previous command is completed.  In cases
where we need that state change to be enabled, we must still wait for
completion.  For instance, pciehp_reset_slot() attempts to disable anything
that might generate a surprise hotplug on slots that support presence
detection.  If we don't wait for those settings to latch before the
secondary bus reset, we negate any value in attempting to prevent the
spurious hotplug.

Create a base function with optional wait and helper functions so that
pcie_write_cmd() turns back into the "safe" interface which waits before
and after issuing a command and add pcie_write_cmd_nowait(), which
eliminates the trailing wait for asynchronous completion.  The following
functions are returned to their previous behavior:

  pciehp_power_on_slot
  pciehp_power_off_slot
  pcie_disable_notification
  pciehp_reset_slot

The rationale is that pciehp_power_on_slot() enables the link and therefore
relies on completion of power-on.  pciehp_power_off_slot() and
pcie_disable_notification() need a wait because data structures may be
freed after these calls and continued signaling from the device would be
unexpected.  And, of course, pciehp_reset_slot() needs to wait for the
scenario outlined above.

Fixes: 3461a068 ("PCI: pciehp: Wait for hotplug command completion lazily")
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# v3.17+
      a5dd4b4b
  3. 24 9月, 2014 3 次提交
    • Y
      PCI: pciehp: Stop disabling notifications during init · 31ff2a5e
      由 Yinghai Lu 提交于 
      During pciehp initialization, we previously wrote two hotplug commands:

  pciehp_probe
    pcie_init
      pcie_disable_notification
        pcie_write_cmd           # command 1
    pcie_init_notification
      pcie_enable_notification
        pcie_write_cmd           # command 2

For controllers with errata like Intel CF118, we previously waited for a
timeout before issuing the second hotplug command because the first command
only updates interrupt enable bits and is not a "real" hotplug command, so
the controller doesn't report Command Completed for it.

But there's no need to disable notifications in the first place.  If BIOS
left them enabled, we could easily take an interrupt before disabling them,
so there's no benefit in disabling them for the tiny window before we
enable them.

Drop the unnecessary pcie_disable_notification() call.

[bhelgaas: changelog]
Link: http://www.intel.com/content/www/us/en/processors/xeon/xeon-e7-v2-spec-update.htmlSigned-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
      31ff2a5e
    • Y
      PCI: pciehp: Add more Slot Control debug output · cf8d7b58
      由 Yinghai Lu 提交于 
      Add more Slot Control debug output and move one print after
pcie_write_cmd() to be consistent with other debug output.
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
      cf8d7b58
    • Y
      PCI: pciehp: Fix wait time in timeout message · d433889c
      由 Yinghai Lu 提交于 
      When we warned about a timeout on a hotplug command, we previously printed
the time between calls to pcie_write_cmd(), without accounting for any time
spent actually waiting.  Consider this sequence:

  pcie_write_cmd
    write SLTCTL
    cmd_started = jiffies          # T1

  pcie_write_cmd
    pcie_wait_cmd
      now = jiffies                # T2
      wait_event_timeout           # we may wait here
      if (timeout)
        ctrl_info("Timeout on command issued %u msec ago",
                  jiffies_to_msecs(now - cmd_started))

We previously printed (T2 - T1), but that doesn't include the time spent in
wait_event_timeout().

Fix this by using the current jiffies value, not the one cached before
calling wait_event_timeout().

[bhelgaas: changelog, use current jiffies instead of adding timeout]
Fixes: 40b96083 ("PCI: pciehp: Compute timeout from hotplug command start time")
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
      d433889c
  5. 23 9月, 2014 1 次提交
  7. 13 9月, 2014 1 次提交
  9. 11 9月, 2014 1 次提交
    • B
      PCI: Add pci_ignore_hotplug() to ignore hotplug events for a device · b440bde7
      由 Bjorn Helgaas 提交于 
      Powering off a hot-pluggable device, e.g., with pci_set_power_state(D3cold),
normally generates a hot-remove event that unbinds the driver.

Some drivers expect to remain bound to a device even while they power it
off and back on again.  This can be dangerous, because if the device is
removed or replaced while it is powered off, the driver doesn't know that
anything changed.  But some drivers accept that risk.

Add pci_ignore_hotplug() for use by drivers that know their device cannot
be removed.  Using pci_ignore_hotplug() tells the PCI core that hot-plug
events for the device should be ignored.

The radeon and nouveau drivers use this to switch between a low-power,
integrated GPU and a higher-power, higher-performance discrete GPU.  They
power off the unused GPU, but they want to remain bound to it.

This is a reimplementation of f244d8b6 ("ACPIPHP / radeon / nouveau:
Fix VGA switcheroo problem related to hotplug") but extends it to work with
both acpiphp and pciehp.

This fixes a problem where systems with dual GPUs using the radeon drivers
become unusable, freezing every few seconds (see bugzillas below).  The
resume of the radeon device may also fail, e.g.,

This fixes problems on dual GPU systems where the radeon driver becomes
unusable because of problems while suspending the device, as in bug 79701:

    [drm] radeon: finishing device.
    radeon 0000:01:00.0: Userspace still has active objects !
    radeon 0000:01:00.0: ffff8800cb4ec288 ffff8800cb4ec000 16384 4294967297 force free
    ...
    WARNING: CPU: 0 PID: 67 at /home/apw/COD/linux/drivers/gpu/drm/radeon/radeon_gart.c:234 radeon_gart_unbind+0xd2/0xe0 [radeon]()
    trying to unbind memory from uninitialized GART !

or while resuming it, as in bug 77261:

    radeon 0000:01:00.0: ring 0 stalled for more than 10158msec
    radeon 0000:01:00.0: GPU lockup ...
    radeon 0000:01:00.0: GPU pci config reset
    pciehp 0000:00:01.0:pcie04: Card not present on Slot(1-1)
    radeon 0000:01:00.0: GPU reset succeeded, trying to resume
    *ERROR* radeon: dpm resume failed
    radeon 0000:01:00.0: Wait for MC idle timedout !

Link: https://bugzilla.kernel.org/show_bug.cgi?id=77261
Link: https://bugzilla.kernel.org/show_bug.cgi?id=79701Reported-by: NShawn Starr <shawn.starr@rogers.com>
Reported-by: NJose P. <lbdkmjdf@sharklasers.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NAlex Deucher <alexander.deucher@amd.com>
Acked-by: NRajat Jain <rajatxjain@gmail.com>
Acked-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: NDave Airlie <airlied@redhat.com>
CC: stable@vger.kernel.org	# v3.15+
      b440bde7
  11. 08 7月, 2014 1 次提交
    • M
      PCI: pciehp: Clear Data Link Layer State Changed during init · 0d25d35c
      由 Myron Stowe 提交于 
      During PCIe hot-plug initialization - pciehp_probe() - data structures
related to slot capabilities are set up.  As part of this set up, ISRs are
put in place to handle slot events and all event bits are cleared out.

This patch adds the Data Link Layer State Changed (PCI_EXP_SLTSTA_DLLSC)
Slot Status bit to the event bits that are cleared out during
initialization.

If the BIOS doesn't clear DLLSC before handoff to the OS, pciehp notices
that it's set and interprets it as a new Link Up event, which results in
spurious messages:

  pciehp 0000:82:04.0:pcie24: slot(4): Link Up event
  pciehp 0000:82:04.0:pcie24: Device 0000:83:00.0 already exists at 0000:83:00, cannot hot-add
  pciehp 0000:82:04.0:pcie24: Cannot add device at 0000:83:00

Prior to e48f1b67 ("PCI: pciehp: Use link change notifications for
hot-plug and removal"), pciehp ignored DLLSC.

Reference:
  PCI-SIG.  PCI Express Base Specification Revision 4.0 Version 0.3
  (PCI-SIG, 2014): 7.8.11. Slot Status Register (Offset 1Ah).

[bhelgaas: add e48f1b67 ref and stable tag]
Fixes: e48f1b67 ("PCI: pciehp: Use link change notifications for hot-plug and removal")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=79611Signed-off-by: NMyron Stowe <myron.stowe@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# v3.15+
      0d25d35c
  13. 06 7月, 2014 1 次提交
  15. 18 6月, 2014 3 次提交
    • B
      PCI: pciehp: Remove assumptions about which commands cause completion events · 2cc56f30
      由 Bjorn Helgaas 提交于 
      We use incorrect logic to decide whether a PCIe hotplug controller
generates command completion events.

5808639b ("pciehp: fix slow probing") assumed that the Slot Status
"Command Completed" bit was set only for commands affecting slot power,
indicators, or electromechanical interlock.  That assumption is false: per
sec. 6.7.3.2 of PCIe spec r3.0, a write targeting any portion of the Slot
Control register is a command, and (if command completed events are
supported) software must wait for a command to complete before issuing the
next command.

5808639b was to fix boot-time timeouts (see bugzilla below) on a Lenovo
Thinkpad R61 with an Intel hotplug controller.  The controller probably has
the Intel CF118 erratum, which means it doesn't report Command Completed
unless the Slot Control power, indicator, or interlock bits are changed.
This causes a timeout because pciehp always waits for Command Complete (if
supported), regardless of which bits are changed.

Remove the incorrect logic because the timeouts have been addressed
differently by these changes:

  PCI: pciehp: Wait for hotplug command completion lazily
  PCI: pciehp: Compute timeout from hotplug command start time

Link: https://bugzilla.kernel.org/show_bug.cgi?id=10751
Tested-by: Rajat Jain <rajatxjain@gmail.com>	(IDT 807a controller)
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
      2cc56f30
    • B
      PCI: pciehp: Compute timeout from hotplug command start time · 40b96083
      由 Bjorn Helgaas 提交于 
      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: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
      40b96083
    • B
      PCI: pciehp: Wait for hotplug command completion lazily · 3461a068
      由 Bjorn Helgaas 提交于 
      Previously we issued a hotplug command and waited for it to complete.  But
there's no need to wait until we're ready to issue the *next* command.  The
next command will probably be much later, so the first one may have already
completed and we may not have to actually wait at all.

Because of hardware errata, some controllers generate command completion
events for some commands but not others.  In the case of Intel CF118 (see
spec update reference), the controller indicates command completion only
for Slot Control writes that change the value of the following bits:

  Power Controller Control
  Power Indicator Control
  Attention Indicator Control
  Electromechanical Interlock Control

Changes to other bits, e.g., the interrupt enable bits, do not cause the
Command Completed bit to be set.  Controllers from AMD and Nvidia are
reported to have similar errata.

These errata cause timeouts when pcie_enable_notification() enables
interrupts.  Previously that timeout occurred at boot-time.  With this
change, the timeout occurs later, when we change the state of the slot
power, indicators, or interlock.  This speeds up boot but causes a timeout
at the first hotplug event on the slot.  Subsequent events don't timeout
because only the first (boot-time) hotplug command updates Slot Control
without touching the power/indicator/interlock controls.

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: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NYinghai Lu <yinghai@kernel.org>
      3461a068
  17. 17 6月, 2014 1 次提交
  19. 11 6月, 2014 2 次提交
  21. 25 4月, 2014 1 次提交
  23. 20 2月, 2014 1 次提交
  25. 12 2月, 2014 4 次提交
  27. 11 2月, 2014 2 次提交
  29. 16 12月, 2013 7 次提交
  31. 15 12月, 2013 1 次提交
  33. 15 11月, 2013 1 次提交
  35. 15 8月, 2013 1 次提交
  37. 04 7月, 2013 1 次提交
  39. 13 1月, 2013 1 次提交
    • Y
      PCI: pciehp: Use per-slot workqueues to avoid deadlock · c2be6f93
      由 Yijing Wang 提交于 
      When we have a hotplug-capable PCIe port with a second hotplug-capable
PCIe port below it, removing the device below the upstream port causes
a deadlock.

The deadlock happens because we use the pciehp_wq workqueue to run
pciehp_power_thread(), which uses pciehp_disable_slot() to remove devices
below the upstream port.  When we remove the downstream PCIe port, we call
pciehp_remove(), the pciehp driver's .remove() method.  That calls
flush_workqueue(pciehp_wq), which deadlocks because the
pciehp_power_thread() work item is still running.

This patch avoids the deadlock by creating a workqueue for every PCIe port
and removing the single shared workqueue.

Here's the call path that leads to the deadlock:

  pciehp_queue_pushbutton_work
    queue_work(pciehp_wq)                   # queue pciehp_power_thread
    ...

  pciehp_power_thread
    pciehp_disable_slot
      remove_board
	pciehp_unconfigure_device
	  pci_stop_and_remove_bus_device
	    ...
	      pciehp_remove                 # pciehp driver .remove method
		pciehp_release_ctrl
		  pcie_cleanup_slot
		    flush_workqueue(pciehp_wq)

This is fairly urgent because it can be caused by simply unplugging a
Thunderbolt adapter, as reported by Daniel below.

[bhelgaas: changelog]
Reference: http://lkml.kernel.org/r/CAMVG2ssiRgcTD1bej2tkUUfsWmpL5eNtPcNif9va2-Gzb2u8nQ@mail.gmail.comReported-and-tested-by: NDaniel J Blueman <daniel@quora.org>
Reviewed-by: NKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: NYijing Wang <wangyijing@huawei.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org
      c2be6f93
  41. 24 8月, 2012 1 次提交
  43. 13 7月, 2012 1 次提交
  45. 15 2月, 2012 3 次提交