[Intel-gfx] [RFC] drm/i915/backlight: switch to unique backlight device names

[Jani Nikula]

On Wed, 07 Apr 2021, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> On Wed, Apr 07, 2021 at 12:08:12PM +0300, Jani Nikula wrote:
>> Change the backlight device names from intel_backlight to
>> card%d-%s-backlight format, for example card0-eDP-1-backlight, to make
>> them unique. Otherwise, registering multiple backlight devices with
>> intel_backlight name will fail, regardless of whether they're two
>> connectors in the same device or two different devices.
>> 
>> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2794
>> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
>> 
>> ---
>> 
>> Is the name "intel_backlight" part of the UABI? In theory the userspace
>> should only look at the names and types available under
>> /sys/class/backlight, not the exact names.
>
> Quick glance at some things suggest this might affect some
> custom setups people have.
>
> There is an xorg.conf option in the intel ddx to force the
> backlight device selection. But I didn't see any hardcoding
> of the backlight device name, so unless the user has
> configured that knob things should keep working I think.
>
> Also googling says systemd might have some backlight
> name to service name magic going on. But I was too lazy
> to actually read the code so don't know the details.

Thanks, I switched to using intel_backlight first, and falling back to
unique names after that [1].

BR,
Jani.

[1] https://patchwork.freedesktop.org/series/89578/

-- 
Jani Nikula, Intel Open Source Graphics Center