Re: 4.5 regression: ACPI hangs when backlight hotkeys are pressed

Andy Lutomirski
2016-01-18T23:58:09Z

On Mon, Jan 18, 2016 at 3:54 PM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> On Monday, January 18, 2016 03:04:28 PM Andy Lutomirski wrote:
>> On Mon, Jan 18, 2016 at 2:25 PM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>> > On Monday, January 18, 2016 12:52:53 PM Andy Lutomirski wrote:
>> >> I'm running 4.4 with the pm+acpi-4.5-rc1-1 merged in. After pressing
>> >> the backlight hotkeys a couple times, things start to break. Poking
>> >> at hung thread stacks, it appears that calls to
>> >> acpi_video_handles_brightness_key_presses never return.
>> >>
>> >> It appears that the culprit is:
>> >>
>> >> commit aecbd9b1bff6afbe349921b406b99d285b412820
>> >> Author: Adrien Schildknecht <adrien+dev@schischi.me>
>> >> Date: Mon Jan 4 23:22:28 2016 +0100
>> >>
>> >> ACPI / video: driver must be registered before checking for keypresses
>> >>
>> >> Reverting that patch makes my laptop work again.
>> >>
>> >> I don't know what that patch is trying to do, but it looks highly
>> >> questionable to me. Why should an accessor wait for a potential
>> >> different driver to register something? I see no guarantee that it
>> >> will eve happen.
>> >>
>> >> This is a Dell XPS 13 9350.
>> >
>> > Should be fixed in my linux-next branch, can you please try that one?
>> >
>>
>> To avoid churning my laptop tree too much, I cherry-picked:
>>
>> ACPI / video: Add disable_backlight_sysfs_if quirk for the Toshiba
>> Satellite R830
>> ACPI / video: Revert "thinkpad_acpi: Use
>> acpi_video_handles_brightness_key_presses()"
>> ACPI / video: Document acpi_video_handles_brightness_key_presses() a bit
>> ACPI / video: Fix using an uninitialized mutex / list_head in
>> acpi_video_handles_brightness_key_presses()
>> ACPI / video: Revert "ACPI / video: driver must be registered before
>> checking for keypresses"
>>
>> The result seems to work. Are you planning on sending these for 4.5?
>
> Yes, I am.
>
> Most likely on Wednesday (or Thursday if anything urgent shows up in the meantime).
>

Sounds good. I'll keep testing.

Some day my laptop will Just Work on a distro kernel :)

--Andy