Bug#688828: xserver-xorg-video-radeon: brightness controls don't work

[Alex Deucher]

On Tue, Sep 25, 2012 at 8:57 PM, Geoff Crompton
<geoffc at trinity.unimelb.edu.au> wrote:
> Package: xserver-xorg-video-radeon
> Version: 1:6.14.4-5
> Severity: normal
>
> Dear Maintainer,
>
> The brightness controls on my iMac aren't effective at changing the brightness
> of either of my displays. They do popup the gnome brightness indicator, and
> alter the values of /sys/class/backlight/acpi_video0/brightness.
>
> But they don't effect the brightness of either the primary display, or the
> secondary display I've got attached (via a thunderbolt to DVI connector).
> Likewise the gnome system settings brightness controls slide around, and do
> alter  /sys/class/backlight/acpi_video0/brightness, but don't change the
> brightness.
>
> Rebooting into Mac and setting the brightness there seems to maintain that
> brightness setting when I reboot back into Linux. I'm booting with grub-efi.

If apple uses the built in GPU backlight controller, it may work with
the new backlight control patches in my drm-3.7 branch:
http://cgit.freedesktop.org/~agd5f/linux/log/?h=drm-next-3.7-wip

Alex