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.
Bjorn
>>> 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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