display: Misc 1024-2047 bl fixes:

 - Only 7T is capable of utilizing this range.
 - Hack of setting >1024 to 2047, and setting HBM on in this scenario.
 - We lose some configurable range on 7T but end up with an overall
   generic solution.
 - Bring back an early return which is needed to avoid dropping out of
   HBM on devices without the >1024 range.

Author: RealJohnGalt

drivers/gpu/drm/msm/dsi-staging/dsi_display.c

@@ -372,9 +372,9 @@ int dsi_display_set_backlight(struct drm_connector *connector,
 	if (rc)
 		pr_debug("unable to set backlight\n");
 
-	if (bl_lvl > 1023 && panel->bl_config.bl_level <= 1023)
+	if (bl_lvl == 2047 && panel->bl_config.bl_level <= 1023)
 		rc = dsi_panel_set_hbm_mode(panel, 5);
-	else if (bl_lvl <= 1023 && panel->bl_config.bl_level > 1023)
+	else if (bl_lvl <= 1023 && panel->bl_config.bl_level == 2047)
 		rc = dsi_panel_set_hbm_mode(panel, 0);
 
 	panel->bl_config.bl_level = bl_lvl;

drivers/gpu/drm/msm/dsi-staging/dsi_panel.c

@@ -891,6 +891,9 @@ static int dsi_panel_update_backlight(struct dsi_panel *panel,
 	dsi = &panel->mipi_device;
 	mode = panel->cur_mode;
 
+	if (panel->is_hbm_enabled || HBM_flag == true)
+		return 0;
+
 	saved_backlight = bl_lvl;
 
 	if (panel->dc_dim)

drivers/gpu/drm/msm/sde/sde_connector.c

@@ -91,14 +91,14 @@ static int sde_backlight_device_update_status(struct backlight_device *bd)
 	bl_lvl = mult_frac(brightness, display->panel->bl_config.bl_max_level,
 			display->panel->bl_config.brightness_max_level);
 
-	//Hack to workaround this range having artifacts or being lower brightness
-	//than 1023
-	if (bl_lvl > 1023 && bl_lvl < 1600)
-		bl_lvl = 1600;
-
 	if (!bl_lvl && brightness)
 		bl_lvl = 1;
 
+	//Hack because 1024-2047 has different issues on different devices
+	//Only 7T is capable of using this range, however we manual set HBM
+	if (bl_lvl > 1023)
+		bl_lvl = 2047;
+
 	if (!c_conn->allow_bl_update) {
 		c_conn->unset_bl_level = bl_lvl;
 		return 0;