On Wednesday, May 21, 2014 07:53:37 AM Bjorn Helgaas wrote:
> On Wed, May 21, 2014 at 3:45 AM, Gavin Guo <gavin.guo@xxxxxxxxxxxxx> wrote:
> > Hi Bjorn,
> >
> > On Wed, May 21, 2014 at 12:54 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> >> On Tue, May 20, 2014 at 10:36 PM, Gavin Guo <gavin.guo@xxxxxxxxxxxxx> wrote:
> >>> Hi all,
> >>>
> >>> I have a APIOTEK PCI-to-USB ExpressCard and found that when it is
> >>> plugged at cold boot, the card can be detected. But, hotplug cannot
> >>> work at run time. The bug may be related to the commit which I
> >>> reported last year:
> >>>
> >>> commit 3f327e39b4b8f760c331bb2836735be6d83fbf53
> >>
> >> Where is your report from last year? How did you identify this
> >> commit? Did you verify that it works correctly with v3.10-rc1, but
> >> fails when you add this commit?
> >
> > The mail about the bug I reported last year is attached. And I'm sorry
> > about not describing clearly. This commit is the one to fix the bug
> > before. So, I think it will be a clue to find out what's wrong. I've
> > built v3.10 and tested it on the platform. It works fine. The bug
> > seems like a regression.
> >
> > I also attached the dmesg of v3.10 which works correctly with hotplug.
>
> v3.10 contains 3f327e39b4b8 (it appeared in v3.10-rc3). So since it
> works correctly in v3.10, that commit is probably not the cause of the
> regression.
>
> So apparently it worked in v3.10 and broke sometime later. Do you
> know when it broke?
>
> We're getting Bus Check events:
>
> ACPI: \_SB_.PCI0: ACPI_NOTIFY_BUS_CHECK event
>
> but apparently we aren't handling them correctly. Can you turn on the
> debug in the acpi_hotplug_schedule() path and add more if necessary to
> if we get to acpi_hotplug_work_fn(), acpi_device_hotplug(), etc.? I'm
> not familiar with that path, so either you'll have to narrow it down,
> or we can hope that Yinghai or Rafael has some insight.
Well, it would be good to create a bug entry for this at bugzilla.kernel.org
against ACPI/Config-hotplug and mark it as a regression.
Rafael
> >>> Author: Yinghai Lu <yinghai@xxxxxxxxxx>
> >>> Date: Tue May 7 11:06:03 2013 -0600
> >>>
> >>> PCI: acpiphp: Re-enumerate devices when host bridge receives Bus Check
> >>>
> >>> When a PCI host bridge device receives a Bus Check notification, we
> >>> must re-enumerate starting with the bridge to discover changes (devices
> >>> that have been added or removed).
> >>>
> >>> Prior to 668192b678 ("PCI: acpiphp: Move host bridge hotplug to
> >>> pci_root.c"), this happened in _handle_hotplug_event_bridge(). After that
> >>> commit, _handle_hotplug_event_bridge() is not installed for host bridges,
> >>> and the host bridge notify handler, _handle_hotplug_event_root() did not
> >>> re-enumerate.
> >>>
> >>> This patch adds re-enumeration to _handle_hotplug_event_root().
> >>>
> >>> This fixes cases where we don't notice the addition or removal of
> >>> PCI devices, e.g., the PCI-to-USB ExpressCard in the bugzilla below.
> >>>
> >>> Dmesg is attached. The scenario of the dmesg: The PCI-to-USB
> >>> ExpressCard is attached at cold boot. Then, you can see that the usb
> >>> storage can be detected in the dmesg. Finally, I've done hotplug 2
> >>> times to see if it can detect the PCI-to-USB ExpressCard. At the end
> >>> of Dmesg, it only has several "ACPI: \_SB_.PCI0: ACPI_NOTIFY_BUS_CHECK
> >>> event" and can't detect the card.
> >>>
> >>> Thanks,
> >>> Gavin Guo
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--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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