Re: [PATCH v3 8/8] drm/i915/backlight: Use default/max brightness for INTEL AUX HDR backlight init

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 24 Feb 2026, Suraj Kandpal <suraj.kandpal@intel.com> wrote:
> If the brightness fetched from VBT/previous state is 0 on backlight
> initialization, then set the brightness to a default/max value.
> Whenever the minimum brightness is reported as 0 there are chances
> we maybe sometimes end up with blank screen. This confuses the user
> into thinking the display is acting weird. This occurs in eDP 1.4b
> when we use proprietary INTEL AUX HDR DPCD registers to manipulate
> brightness via luminance values.
>
> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
> Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
> ---
> v1 -> v2:
> - Let users set brightness to 0, make it so that it's just not
> done by default (Arun)
>
> v1 -> v2:
> - Update commit header & message (Arun)
>
>  drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> index aac6cdb5b69b..725370bcfa3b 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> @@ -442,6 +442,8 @@ intel_dp_aux_hdr_setup_backlight(struct intel_connector *connector, enum pipe pi
>  
>  	panel->backlight.level = intel_dp_aux_hdr_get_backlight(connector, pipe);
>  	panel->backlight.enabled = panel->backlight.level != 0;
> +	if (!panel->backlight.level)
> +		panel->backlight.level = panel->backlight.max;

Same here, .enabled is still based on level != 0 above.

>  
>  	return 0;
>  }

-- 
Jani Nikula, Intel