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

Andy Lutomirski
2016-01-18T23:04:48Z

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?

--Andy