[Intel-gfx] Brightness control fails between 3.6.8 and 3.7.0-rc7 (Intel 915/Dell Vostro 3560)

[Daniel Vetter]

On Sun, Dec 2, 2012 at 2:49 PM, Tom St Denis <tstdenis at elliptictech.com> wrote:
> Ok so on v3.7-rc1 [and I suspect up] I can manually control the brightness by echoing to
>
> /sys/class/backlight/intel_backlight/brightness
>
> But I still can't use the buttons to control it (it only goes one tick down from max and stops there).  I'm using GNOME3 from a x86_64 unstable debian install [up to date with latest].
>
> I just noticed that under v3.7 I have a new directory /sys/class/backlight/acpi_video1 which is what GNOME is actually controlling.  I can't disable ACPI video control so is there a workaround?

Hah, acpi registered a broken backlight driver, which overwrites the
intel backlight - for once it's not i915.ko's fault ;-) For a
workaround either disable the acpi backlight with
acpi_backlight=vendor (iirc) kernel option or teach the X driver that
you want a different backlight driver in the xorg.conf (Option
"Backlight" "intel_backlight" should do the trick).
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch