drm/i915/backlight: Enable nits based luminance

Enable nits based luminance by writing the PANEL_LUMINANCE_CONTROL
bit and set the correct register to change brightness.

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Tested-by: Ben Kao <ben.kao@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250206063253.2827017-9-suraj.kandpal@intel.com

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 301a4dfdfbe5ffa3f221a1d47703000d7743abe3..f53c8355d5bea5515e177e9ce2b508a1f98424e3 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -527,6 +527,18 @@ intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
        struct intel_connector *connector = to_intel_connector(conn_state->connector);
        struct intel_panel *panel = &connector->panel;
        struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
+       int ret;
+
+       if (panel->backlight.edp.vesa.luminance_control_support) {
+               ret = drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
+                                        DP_EDP_PANEL_LUMINANCE_CONTROL_ENABLE);
+
+               if (ret == 1)
+                       return;
+
+               if (!intel_dp_aux_vesa_set_luminance(connector, level))
+                       return;
+       }
 
        if (!panel->backlight.edp.vesa.info.aux_enable) {
                u32 pwm_level;
@@ -550,6 +562,9 @@ static void intel_dp_aux_vesa_disable_backlight(const struct drm_connector_state
        struct intel_panel *panel = &connector->panel;
        struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
 
+       if (panel->backlight.edp.vesa.luminance_control_support)
+               return;
+
        drm_edp_backlight_disable(&intel_dp->aux, &panel->backlight.edp.vesa.info);
 
        if (!panel->backlight.edp.vesa.info.aux_enable)