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

[Suraj Kandpal]

Check if we are capable of controlling brightness via luminance
which is dependent on PANEL_LUMINANCE_OVERRIDE being set.

--v2
-Prefer using luminance rather than nits [Jani]
-Fix commit message

Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
Tested-by: Ben Kao <ben.kao at 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 cb51b7936f93..3b64ad724b29 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 luminance_control_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..84126e7d1716 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 Luminance Based Backlight Control Supported!\n",
+			    connector->base.base.id, connector->base.name);
+		panel->backlight.edp.vesa.luminance_control_support = true;
+		return true;
+	}
 
 	if (drm_edp_backlight_supported(intel_dp->edp_dpcd)) {
 		drm_dbg_kms(display->drm,
-- 
2.34.1