Re: [PATCH 3/7] drm/i915/backlight: Check Nits based brightness control for VESA

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

On Fri, 24 Jan 2025, Suraj Kandpal <suraj.kandpal@intel.com> wrote:
> Check if we are capable of controlling brightness via Nits which
> is dependant on PANEL_LUMINANCE_OVERRIDE and SMOOTH_BRIGHTNESS
> capablility being set.
>
> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display_types.h    | 1 +
>  drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 9 +++++++++
>  2 files changed, 10 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 083eb86f0904..f900e1f2d93e 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -412,6 +412,7 @@ struct intel_panel {
>  		union {
>  			struct {
>  				struct drm_edp_backlight_info info;
> +				bool nits_support;
>  			} vesa;
>  			struct {
>  				bool sdr_uses_aux;
> 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 09e82f24d030..c5ff6e044866 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> @@ -575,6 +575,15 @@ intel_dp_aux_supports_vesa_backlight(struct intel_connector *connector)
>  {
>  	struct intel_display *display = to_intel_display(connector);
>  	struct intel_dp *intel_dp = intel_attached_dp(connector);
> +	struct intel_panel *panel = &connector->panel;
> +
> +	if ((intel_dp->edp_dpcd[2] & DP_EDP_PANEL_LUMINANCE_CONTROL_CAPABLE)) {
> +		drm_dbg_kms(display->drm,
> +			    "[CONNECTOR:%d:%s] AUX Nits Based Backlight Control Supported!\n",
> +			    connector->base.base.id, connector->base.name);
> +		panel->backlight.edp.vesa.nits_support = true;

Should we refer to luminance rather than nits here?

BR,
Jani.


> +		return true;
> +	}
>  
>  	if (drm_edp_backlight_supported(intel_dp->edp_dpcd)) {
>  		drm_dbg_kms(display->drm,

-- 
Jani Nikula, Intel