pciehp: Fix interrupt event handlig
authorKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Fri, 25 Apr 2008 21:38:57 +0000 (14:38 -0700)
committerJesse Barnes <jbarnes@virtuousgeek.org>
Fri, 25 Apr 2008 21:38:57 +0000 (14:38 -0700)
commitc6b069e94601aea8887afbbd922afe20a3580a7d
tree09c1323f36040f039d3b260e794bcc3c4e16d4f1
parent3800345f723fd130d50434d4717b99d4a9f383c8
pciehp: Fix interrupt event handlig

Current pciehp implementation disables and re-enables hotplug interrupts
in its interrupt handler. This operation might be intend to guarantee
that interrupts for the events newly occured during previous events are
being handled will be successfully generated. But current implementaion
has the following prolems.

  - Current interrupt service routin clears status changes without
    waiting command completion. Because of this, events might not be
    cleared properly.
  - Current interrupt service routine clears status changes caused by
    disabling or enabling hotplug interrupts itself. This will lose new
    events that occurs during previous interrupts are being handled.
  - Current implementation doesn't have any serialization mechanism
    between the code to wait for command completion and the interrupt
    handler that clears the command completion events caused by itself.
    There is clearly race conditions between them, and it may cause
    the problem that waiting for command completion doesn't work for
    example.

To fix those problems, this patch stops disabling/re-enabling hotplug
interrupts in interrupt service routine. Instead of this, this patch
re-inspects Slot Status register after clearing what is presumed to
be the last bending interrupt in order to guarantee that all interrupt
events are serviced.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
drivers/pci/hotplug/pciehp.h
drivers/pci/hotplug/pciehp_hpc.c