linux-kernel - Re: [REGRESSION] probe with driver acpi-fan failed with error -22

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Date: Tue,  4 Jun 2024 14:55:09 +0200
From: Laura Nao <laura.nao@...labora.com>
To: rafael@...nel.org
Cc: kernel@...labora.com,
	laura.nao@...labora.com,
	lenb@...nel.org,
	linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	regressions@...ts.linux.dev
Subject: Re: [REGRESSION] probe with driver acpi-fan failed with error -22

Hi Rafael,

On 6/4/24 14:07, Rafael J. Wysocki wrote:
> On Mon, Jun 3, 2024 at 8:20 PM Rafael J. Wysocki <rafael@...nel.org>
> wrote:
>>
>> Hi,
>>
>> On Fri, May 31, 2024 at 1:35 PM Laura Nao <laura.nao@...labora.com>
>> wrote:
>>>
>>> Hello,
>>>
>>> On 5/30/24 17:37, Laura Nao wrote:
>>>> Hello,
>>>>
>>>> We have identified a regression in the acpi-fan driver probe
>>>> between
>>>> v6.9-rc7 and v6.10-rc1 on some Intel Chromebooks in the Collabora
>>>> LAVA
>>>> lab.
>>>>
>>>> For the Acer Chromebook Spin 514 (CP514-2H), the following error is
>>>> reported in the logs:
>>>>
>>>> [    0.651202] acpi-fan INTC1044:00: probe with driver acpi-fan
>>>> failed with error -22
>>>>
>>>> Similar errors are reported on other devices with fans compatible
>>>> with
>>>> the same driver.
>>>>
>>>> On Acer Chromebox CXI4, ASUS Chromebook Flip C436FA and
>>>> HP Chromebook x360 14 G1:
>>>>
>>>> [    0.488001] acpi-fan INT3404:00: probe with driver acpi-fan
>>>> failed with error -22
>>>>
>>>> On ASUS Chromebook Vero 514 CBV514-1H:
>>>>
>>>> [    1.168905] acpi-fan INTC1048:00: probe with driver acpi-fan
>>>> failed with error -22
>>>>
>>>> The issue is still present on next-20240529.
>>>>
>>>> I'm sending this report to track the regression while a fix is
>>>> identified. I'll investigate the issue/run a bisection and report
>>>> back
>>>> with the results.
>>>>
>>>> This regression was discovered during some preliminary tests with
>>>> the
>>>> ACPI probe kselftest [1] in KernelCI. The config used was the
>>>> upstream
>>>> x86_64 defconfig with a fragment applied on top [2].
>>>>
>>>> Best,
>>>>
>>>> Laura
>>>>
>>>> [1]
>>>> https://lore.kernel.org/all/20240308144933.337107-1-laura.nao@collabora.com/
>>>> [2] https://pastebin.com/raw/0tFM0Zyg
>>>>
>>>> #regzbot introduced: v6.9-rc7..v6.10-rc1
>>>
>>> The issue started happening after:
>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/thermal/thermal_core.c?h=v6.10-rc1&id=31a0fa0019b022024cc082ae292951a596b06f8c
>>>
>>> Before this commit, get_cur_state() was not called by
>>> __thermal_cooling_device_register, so the error was not triggered.
>>>
>>> After enabling debugging for the acpi-fan driver, I noticed these
>>> errors
>>> in the logs:
>>>
>>> [    0.682224] acpi INTC1044:00: Invalid control value returned
>>> [    0.682635] acpi INTC1044:00: Invalid control value returned
>>>
>>> The value stored in fst.control is 255, which is indeed not a valid
>>> value.
>>>
>>> I suspect this might be a firmware issue that is now manifesting due
>>> to
>>> the addition of the extra get_cur_state() call.
>>>
>>> I'll dig a bit more and report back.
>>
>> It looks like _FST returns all ones if it is evaluated before _FSL on
>> the affected platforms.
>>

Right, I'll look into that.

>> It shouldn't do that, but then it is not particularly useful to fail
>> cdev registration for this reason.
>>
>> The attached patch should work around this issue, please try it and
>> report back.
> 
> A !ret check is missing in that patch, so please try the attached new
> version of it instead.
>
> Thanks!

I confirm the patch works as expected and fixes the probe issue.

Thank you!

Laura