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

[Tom St Denis]

Thanks Daniel so I'm taking back my bug report on the i915 and claiming this as a bug against the acpi_video stack.

What sort of information would the ACPI folk like from me to help diagnose this?

Here's a dmesg dump of all ACPI messages.

http://pastebin.com/b4XKe5Fk

Tom

----- Original Message -----
> From: "Daniel Vetter" <daniel.vetter at ffwll.ch>
> To: "Tom St Denis" <tstdenis at elliptictech.com>
> Cc: linux-kernel at vger.kernel.org, "intel-gfx" <intel-gfx at lists.freedesktop.org>, "dri-devel"
> <dri-devel at lists.freedesktop.org>
> Sent: Sunday, 2 December, 2012 9:42:39 AM
> Subject: Re: Brightness control fails between 3.6.8 and 3.7.0-rc7 (Intel 915/Dell Vostro 3560)
> 
> 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
>