[Intel-gfx] Developing a new backlight driver for specific OLED screen

[Jani Nikula]

On Fri, 09 Sep 2022, Rodrigo Vivi <rodrigo.vivi at intel.com> wrote:
> On Fri, Sep 09, 2022 at 11:35:28AM +0200, Aurélien wrote:
>>    Hi,
>>    I hope this mailing-mist is the right place for this question.
>
> + dri-devel mailing list that looks more appropriated.
> + Hans and Lyude who were recently working to standardize some of the
> backlight stuff.
>
>>    I would like to develop a new driver in order to manage backlight for a
>>    specific OLED display (Samsung one). For that propose I need to use the
>>    dpcd aux read and write functions.
>>    Since this driver is independent film the i915 driver I would like to
>>    develop an indémependant driver.
>>    So my question is: how can I use the i915 API (dpcd aux communications)
>>    outside from the driver and register the backlight sys entries like the
>>    i915 does (in order to have all the softwares which plays with the
>>    backlight working without modifying them) ?
>
> I don't believe you want to use the i915 API, but move the common functions
> to the drm subsystem itself and then reuse as a drm device.

Aurélien, are you aware of drivers/gpu/drm/display/drm_dp_helper.c and
all the functions around struct dp_aux_backlight and struct
drm_edp_backlight_info?

Also see drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c.

Does the display use some proprietary, non-VESA DPCD registers? There's
already some of that in i915 for Intel proprietary interfaces.


BR,
Jani.



>
>>    Many thanks for your answers
>>    --
>>    Aurélien

-- 
Jani Nikula, Intel Open Source Graphics Center