Revert "drm/dsi: Fix byte order of DCS set/get brightness"

The commit 8a744ca663 ("ANDROID: drm/dsi: Fix byte order of DCS
set/get brightness") modified the upstream API and this makes us
hard to reconcile it to android-4.19 without breaking APIs for GKI.
Rollback the upstream API and implement it in the downstream side.

Bug: 156865857
Change-Id: I0f11aec2249d305dbed77b05b197f67ffbfb00dd
Signed-off-by: Ken Huang <kenbshuang@google.com>
Signed-off-by: Chris Lu <luchris@google.com>
Signed-off-by: Will Mcvicker <willmcvicker@google.com>
Signed-off-by: Srinivasarao P <spathi@codeaurora.org>

drivers/gpu/drm/drm_mipi_dsi.c

@@ -1052,33 +1052,17 @@ EXPORT_SYMBOL(mipi_dsi_dcs_set_tear_scanline);
  *    display
  * @dsi: DSI peripheral device
  * @brightness: brightness value
- * @num_params: Number of parameters (bytes) to encode brightness value in. The
- *              MIPI specification states that one parameter shall be sent for
- *              devices that support 8-bit brightness levels. For devices that
- *              support brightness levels wider than 8-bit, two parameters
- *              shall be sent.
  *
  * Return: 0 on success or a negative error code on failure.
  */
 int mipi_dsi_dcs_set_display_brightness(struct mipi_dsi_device *dsi,
-					u16 brightness, size_t num_params)
+					u16 brightness)
 {
-	u8 payload[2];
+	u8 payload[2] = { brightness & 0xff, brightness >> 8 };
 	ssize_t err;
 
-	switch (num_params) {
-	case 1:
-		payload[0] = brightness & 0xff;
-		break;
-	case 2:
-		payload[0] = brightness >> 8;
-		payload[1] = brightness & 0xff;
-		break;
-	default:
-		return -EINVAL;
-	}
 	err = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
-				 payload, num_params);
+				 payload, sizeof(payload));
 	if (err < 0)
 		return err;
 
@@ -1091,25 +1075,16 @@ EXPORT_SYMBOL(mipi_dsi_dcs_set_display_brightness);
  *    of the display
  * @dsi: DSI peripheral device
  * @brightness: brightness value
- * @num_params: Number of parameters (i.e. bytes) the brightness value is
- *              encoded in. The MIPI specification states that one parameter
- *              shall be returned from devices that support 8-bit brightness
- *              levels. Devices that support brightness levels wider than
- *              8-bit return two parameters (i.e. bytes).
  *
  * Return: 0 on success or a negative error code on failure.
  */
 int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,
-					u16 *brightness, size_t num_params)
+					u16 *brightness)
 {
-	u8 payload[2];
 	ssize_t err;
 
-	if (!(num_params == 1 || num_params == 2))
-		return -EINVAL;
-
 	err = mipi_dsi_dcs_read(dsi, MIPI_DCS_GET_DISPLAY_BRIGHTNESS,
-				payload, num_params);
+				brightness, sizeof(*brightness));
 	if (err <= 0) {
 		if (err == 0)
 			err = -ENODATA;
@@ -1117,15 +1092,6 @@ int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,
 		return err;
 	}
 
-	switch (num_params) {
-	case 1:
-		*brightness = payload[0];
-		break;
-	case 2:
-		*brightness = payload[0] << 8 || payload[1];
-		break;
-	}
-
 	return 0;
 }
 EXPORT_SYMBOL(mipi_dsi_dcs_get_display_brightness);

drivers/gpu/drm/panel/panel-jdi-lt070me05000.c

@@ -341,7 +341,7 @@ static int dsi_dcs_bl_get_brightness(struct backlight_device *bl)
 
 	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
 
-	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness, 1);
+	ret = mipi_dsi_dcs_get_display_brightness(dsi, &brightness);
 	if (ret < 0)
 		return ret;
 
@@ -357,7 +357,7 @@ static int dsi_dcs_bl_update_status(struct backlight_device *bl)
 
 	dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
 
-	ret = mipi_dsi_dcs_set_display_brightness(dsi, bl->props.brightness, 1);
+	ret = mipi_dsi_dcs_set_display_brightness(dsi, bl->props.brightness);
 	if (ret < 0)
 		return ret;
 

drivers/gpu/drm/panel/panel-samsung-s6e63j0x03.c

@@ -365,7 +365,7 @@ static int s6e63j0x03_enable(struct drm_panel *panel)
 		return ret;
 
 	/* set default white brightness */
-	ret = mipi_dsi_dcs_set_display_brightness(dsi, 0x00ff, 1);
+	ret = mipi_dsi_dcs_set_display_brightness(dsi, 0x00ff);
 	if (ret < 0)
 		return ret;
 

include/drm/drm_mipi_dsi.h

@@ -283,9 +283,9 @@ int mipi_dsi_dcs_set_tear_on(struct mipi_dsi_device *dsi,
 int mipi_dsi_dcs_set_pixel_format(struct mipi_dsi_device *dsi, u8 format);
 int mipi_dsi_dcs_set_tear_scanline(struct mipi_dsi_device *dsi, u16 scanline);
 int mipi_dsi_dcs_set_display_brightness(struct mipi_dsi_device *dsi,
-					u16 brightness, size_t num_params);
+					u16 brightness);
 int mipi_dsi_dcs_get_display_brightness(struct mipi_dsi_device *dsi,
-					u16 *brightness, size_t num_params);
+					u16 *brightness);
 
 /**
  * struct mipi_dsi_driver - DSI driver