gpu: drm: adp: Use 16-bit writes for brightness

Some summit panels like the ones found on the main display of iPhone X
has a max brightness of 2047 and needs 16-bit writes.

Tested-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Signed-off-by: Nick Chan <towinchenmi@gmail.com>

Author: asdfugil

drivers/gpu/drm/adp/panel-summit.c

@@ -13,8 +13,8 @@ static int summit_set_brightness(struct device *dev)
 {
 	struct summit_data *panel = dev_get_drvdata(dev);
 	int level = backlight_get_brightness(panel->bl);
-	ssize_t err = mipi_dsi_dcs_write(panel->dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
-					 &level, 1);
+	int err = mipi_dsi_dcs_set_display_brightness(panel->dsi, level);
+
 	if (err < 0)
 		return err;
 	return 0;
@@ -70,10 +70,10 @@ static int summit_resume(struct device *dev)
 
 static int summit_suspend(struct device *dev)
 {
-	int level = 0;
 	struct summit_data *panel = dev_get_drvdata(dev);
-	ssize_t err = mipi_dsi_dcs_write(panel->dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
-					 &level, 1);
+
+	int err = mipi_dsi_dcs_set_display_brightness(panel->dsi, 0);
+
 	if (err < 0)
 		return err;
 	return 0;