[PATCH 7/7] drm/i915/backlight: Enable nits based luminance

[Suraj Kandpal]

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 at intel.com>
Tested-by: Ben Kao <ben.kao at intel.com>
---
 .../gpu/drm/i915/display/intel_dp_aux_backlight.c | 15 +++++++++++++++
 1 file changed, 15 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 38e2b8cc591c..a090f1fca66e 100644
--- 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)
-- 
2.34.1