disp: msm: sde: delay backlight update until the first commit

In the current implementation panel set backlight can be called even before
receiving a frame from the driver during the first commit. Hence there is
chance for some garbage content to be shown onto the panel. So this change
imposes a condition to delay backlight update of the panel until the
first frame is received from the HW.

This change includes only a missing portion of the original that was somehow
left out of the snapshot ported to 4.19. Original change ID is preserved.

Change-Id: I735a97088efef91159e724bba615549dba49e4e3
Signed-off-by: Tharun Raj Soma <[email protected]>
Signed-off-by: Steve Cohen <[email protected]>

msm/sde/sde_connector.c

@@ -535,21 +535,27 @@ static int _sde_connector_update_bl_scale(struct sde_connector *c_conn)
 
 	bl_config = &dsi_display->panel->bl_config;
 
-	if (c_conn->bl_scale > MAX_BL_SCALE_LEVEL)
-		bl_config->bl_scale = MAX_BL_SCALE_LEVEL;
-	else
-		bl_config->bl_scale = c_conn->bl_scale;
+	if (dsi_display->panel->bl_config.bl_update ==
+			BL_UPDATE_DELAY_UNTIL_FIRST_FRAME &&
+			!c_conn->allow_bl_update) {
+		c_conn->unset_bl_level = bl_config->bl_level;
+		return 0;
+	}
 
-	if (c_conn->bl_scale_sv > MAX_SV_BL_SCALE_LEVEL)
-		bl_config->bl_scale_sv = MAX_SV_BL_SCALE_LEVEL;
-	else
-		bl_config->bl_scale_sv = c_conn->bl_scale_sv;
+	if (c_conn->unset_bl_level)
+		bl_config->bl_level = c_conn->unset_bl_level;
+
+	bl_config->bl_scale = c_conn->bl_scale > MAX_BL_SCALE_LEVEL ?
+			MAX_BL_SCALE_LEVEL : c_conn->bl_scale;
+	bl_config->bl_scale_sv = c_conn->bl_scale_sv > MAX_SV_BL_SCALE_LEVEL ?
+			MAX_SV_BL_SCALE_LEVEL : c_conn->bl_scale_sv;
 
 	SDE_DEBUG("bl_scale = %u, bl_scale_sv = %u, bl_level = %u\n",
 		bl_config->bl_scale, bl_config->bl_scale_sv,
 		bl_config->bl_level);
 	rc = c_conn->ops.set_backlight(&c_conn->base,
 			dsi_display, bl_config->bl_level);
+	c_conn->unset_bl_level = 0;
 
 	return rc;
 }