Re: [PATCH 2/2] drm/i915/backlight: Modify condition to use panel luminance

["Nautiyal, Ankit K" <ankit.k.nautiyal@intel.com>]

On 4/8/2025 10:31 AM, Suraj Kandpal wrote:
> According to our internal spec we need to now check if both
> panel luminance and smooth brightness are available in panel for
> us to be able to change brightness using luminance value.

Since DP_EDP_SMOOTH_BRIGHTNESS_CAPABLE is introduced in eDP2.0 and

DP_EDP_PANEL_LUMINANCE_CONTROL_CAPABLE was introduced in eDP1.5

is it like that we intended this for eDP2.0 only and not for eDP1.5 panels?

This will perhaps change the behavior for existing eDP1.5 panel. Do we 
need to add a fix me?

Regards,

Ankit

>
> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
> ---
>   drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> 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 8173de8aec63..20ab90acb351 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> @@ -663,7 +663,8 @@ intel_dp_aux_supports_vesa_backlight(struct intel_connector *connector)
>   	struct intel_dp *intel_dp = intel_attached_dp(connector);
>   	struct intel_panel *panel = &connector->panel;
>   
> -	if ((intel_dp->edp_dpcd[3] & DP_EDP_PANEL_LUMINANCE_CONTROL_CAPABLE)) {
> +	if ((intel_dp->edp_dpcd[3] & DP_EDP_PANEL_LUMINANCE_CONTROL_CAPABLE) &&
> +	    (intel_dp->edp_dpcd[3] & DP_EDP_SMOOTH_BRIGHTNESS_CAPABLE)) {
>   		drm_dbg_kms(display->drm,
>   			    "[CONNECTOR:%d:%s] AUX Luminance Based Backlight Control Supported!\n",
>   			    connector->base.base.id, connector->base.name);