Kay Sievers kay.sievers at
Wed Apr 28 04:27:14 PDT 2010

On Wed, Apr 28, 2010 at 12:19, Patrice Dumas <pertusus at> wrote:
> On Wed, Apr 28, 2010 at 11:51:58AM +0200, Kay Sievers wrote:
>> It should be reasonable simple to let X provide internally a generic
>> sysfs backlight driver which can be wired up from individual drivers
>> like radeon.
> I am a complete outsider here, but my first reaction would be to say
> that backlight is much lower level than X. It is also relevant in
> console mode, for framebuffer... More a driver issue than an X issue.

It's the other way around. if X is taking control over the screen, it
should take control over the backlight.

Console issues, and custom setups are not really covered here. And I
guess they always need custom stuff anyway.

> It seems to me that the right reaction is
>  Alex Deucher      2010-04-27 15:52:23 PDT
>  What do we do on systems with drivers that don't support randr 1.2?  Pretty
>  much all systems with a backlight control use the kernel backlight interface.

Sure, and some of the current X drivers already use exactly that.

> Then the response seems to refer to DRM which is something I am not
> familiar with, but it seems to be something that other components than X
> cannot use easily.

The backlight is in /sys, everybody with the proper privileges can use
this text-based interface.

This is about providing and not providing abstract interfaces, not to
solve uncommon cases which we can not really solve anyway. :)


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