drm/dsi: Implement DCS set disp brightness 2bytes

Provide a small convenience wrapper that set the display 2bytes
brightness

Port from: 4a5c926

Change-Id: Iadfcb1d6cdf4866391f36ee970d79840e109fe9a
Signed-off-by: Bang Nguyen <bangnguyen@motorola.com>
Reviewed-on: https://gerrit.mot.com/1410287
SME-Granted: SME Approvals Granted
SLTApproved: Slta Waiver
Tested-by: Jira Key
Submit-Approved: Jira Key
Reviewed-on: https://gerrit.mot.com/1509783
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>

drivers/gpu/drm/drm_mipi_dsi.c

@@ -1096,6 +1096,29 @@ int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,
 }
 EXPORT_SYMBOL(mipi_dsi_dcs_get_display_brightness);
 
+/**
+ * mipi_dsi_dcs_set_display_brightness_2bytes() - sets the brightness value of
+ *    the display with 2bytes value
+ * @dsi: DSI peripheral device
+ * @brightness: brightness value
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int mipi_dsi_dcs_set_display_brightness_2bytes(struct mipi_dsi_device *dsi,
+					u16 brightness)
+{
+	u8 payload[2] = { (brightness & 0xff00) >> 8, brightness & 0xff};
+	ssize_t err;
+
+	err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
+				payload, sizeof(payload));
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+EXPORT_SYMBOL(mipi_dsi_dcs_set_display_brightness_2bytes);
+
 static int mipi_dsi_drv_probe(struct device *dev)
 {
 	struct mipi_dsi_driver *drv = to_mipi_dsi_driver(dev->driver);

include/drm/drm_mipi_dsi.h

@@ -286,6 +286,9 @@ int mipi_dsi_dcs_set_display_brightness(struct mipi_dsi_device *dsi,
 					u16 brightness);
 int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,
 					u16 *brightness);
+int mipi_dsi_dcs_set_display_brightness_2bytes(struct mipi_dsi_device *dsi,
+					u16 brightness);
+
 
 /**
  * struct mipi_dsi_driver - DSI driver