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

Rafael J. Wysocki
2016-01-18T22:24:29Z

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?

Rafael