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From: Bjorn Helgaas <bhelgaas@google.com>
Date: Tue, 9 Jul 2013 14:19:16 -0600
Message-ID: <CAErSpo6L21RapNxPsBr=+7TeK9StTTj_Vx8D9PTeEXz+yOs0wg@mail.gmail.com>
Subject: Re: 3.8.0-rc4+ - Oops on removing WinTV-HVR-1400 expresscard TV Tuner
To: Chris Clayton <chris2553@gmail.com>
Cc: Martin Mokrejs <mmokrejs@fold.natur.cuni.cz>,
        Yijing Wang <wangyijing@huawei.com>,
        Yijing Wang <wangyijing0307@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "Rafael J. Wysocki" <rjw@sisk.pl>
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On Tue, Jul 9, 2013 at 3:35 AM, Chris Clayton <chris2553@gmail.com> wrote:
> Hello again, Bjorn.
>
> On 04/01/13 18:28, Bjorn Helgaas wrote:
>
> <snip>
>
>
>>>> Hi Chris,
>>>>
>>>> The current Linux acpiphp driver doesn't do anything unless it finds
>>>> devices with _EJ0 or _RMV methods, and your DSDT has neither.  But I
>>>> think that implementation is incorrect because I'm not convinced that
>>>> those methods are required in order to do hotplug via ACPI.  For
>>>> example, your DSDT *does* have an _L01 method that does notifications
>>>> to the root ports.  I suspect that hotplug events on your box generate
>>>> an SCI that invokes that method.  Linux basically ignores the
>>>> resulting notify events, and I suspect that hotplug works on Windows
>>>> because it is paying attention to them.
>>>>
>>>> Can you build a kernel with CONFIG_ACPI_DEBUG=y, do the following, and
>>>> attach all the output to the bugzilla?
>>>>
>>>> 1) Boot with empty ExpressCard slot (without using "pcie_ports=native")
>>>> 2) # echo 0x00010004 > /sys/module/acpi/parameters/debug_layer
>>>> 3) # echo 0x08000004 > /sys/module/acpi/parameters/debug_level
>>>> 4) # lspci -vv
>>>> 5) # setpci -s 1c.3 0x42.w
>>>> 6) # setpci -s 1c.3 0x5a.w
>>>> 7) # setpci -s 1c.3 0xd8.l
>>>> 8) Insert ExpressCard
>>>> 9) # setpci -s 1c.3 0x5a.w
>>>> 10) # dmesg
>>>>
>>>> Here's what I think we'll see:
>>>>
>>>> - Slot Implemented (bit 8 of XCAP at 0x42) set, indicating a slot is
>>>> implemented below this root port
>>>> - Hot Plug SCI Enable (bit 30 of MPC at 0xd8) set, indicating that the
>>>> root port should generate an SCI whenever a hotplug event is detected
>>>> - Presence Detect State (bit 6 of SLTSTS at 0x5a) change from 0 with
>>>> the slot empty to 1 with the slot occupied
>>>> - pciehp doing nothing (since _OSC didn't grant the OS permission to
>>>> use PCIe native hotplug)
>>>> - dmesg indication of the SCI, leading to a Bus Check notification to
>>>> \_SB.PCI0.RP04, which is the 1c.3 root port leading to the ExpressCard
>>>> slot
>>>>
>>>
>>> As far as I can see, your predicted outcomes where correct. I've added
>>> the
>>> logs to the bugzilla report.
>>
>>
>> Yes, it behaved exactly as I expected.  I attached a few more details
>> of the analysis to the bug report
>> (https://bugzilla.kernel.org/show_bug.cgi?id=54981).  I think we need
>> to rework acpiphp to fix this.  We will fix it, but I don't know who
>> will do it, or when it will happen.  My list is growing faster than I
>> can deal with :(
>>
>
> I see that there has been quite a bit of work in the acpiphp area recently.
> Is any of it intended to fix (or ease the subsequent fixing of) this bug
> report, please?

The problem on your system is that acpiphp doesn't work correctly
because it expects a certain combination of _ADR/_EJ0/_RMV methods,
and your system doesn't quite match.  Rafael's acpiphp work is
definitely addressing that issue, but I don't know whether he's made
it far enough yet.

I doubt that work will appear in a v3.11-rc release, though.  More
likely it will appear in -next fairly soon and will first appear in
Linus' tree in v3.12-rc1.  So if you want to test it, either try out
-next or wait for v3.12-rc1.

> It's not a big deal if it isn't - I do have a system that, via kernel
> command line arguments, recognises expresscard devices when I plug them into
> the slot. But when the release comes along that includes the reworking of
> acpiphp that you mentioned, I will give extra attention to hotplugging when
> I try out the -rc kernels on my laptop.

Thanks!  We'll certainly appreciate any testing reports.

Bjorn
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