drm/dp: Introduce new member in drm_backlight_info

Introduce luminance_set flag which indicates if we can manipulate
backlight using luminance value or not which is only possible
after eDP v1.5.

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://lore.kernel.org/r/20250620063445.3603086-2-suraj.kandpal@intel.com

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index 896bba2adb3ba945af3455a3e3df37c75eb2da88..c63f482cdba7e3d32392b1e6e3e73cdde38dade5 100644 (file)
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -4261,11 +4261,15 @@ drm_edp_backlight_init(struct drm_dp_aux *aux, struct drm_edp_backlight_info *bl
                bl->aux_set = true;
        if (edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
                bl->lsb_reg_used = true;
+       if ((edp_dpcd[0] & DP_EDP_15) && edp_dpcd[3] &
+           (DP_EDP_PANEL_LUMINANCE_CONTROL_CAPABLE))
+               bl->luminance_set = true;
 
        /* Sanity check caps */
-       if (!bl->aux_set && !(edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP)) {
+       if (!bl->aux_set && !(edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP) &&
+           !bl->luminance_set) {
                drm_dbg_kms(aux->drm_dev,
-                           "%s: Panel supports neither AUX or PWM brightness control? Aborting\n",
+                           "%s: Panel does not support AUX, PWM or luminance-based brightness control. Aborting\n",
                            aux->name);
                return -EINVAL;
        }

diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index e4ca35143ff965ad4fc8e88fcb094fa0dfe714b3..beafbc31f9d952c26c101861c80e3329c103bb85 100644 (file)
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -849,6 +849,7 @@ struct drm_edp_backlight_info {
        bool lsb_reg_used : 1;
        bool aux_enable : 1;
        bool aux_set : 1;
+       bool luminance_set : 1;
 };
 
 int