drm/dsi: Use peripheral's channel for DCS commands

When executing DCS commands, use the channel associated with the DSI
peripheral rather than one explicitly specified in the function call.
Devices shouldn't be able to step on each others' toes like this.
Acked-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/drm_mipi_dsi.c

@@ -201,16 +201,15 @@ EXPORT_SYMBOL(mipi_dsi_detach);
 /**
  * mipi_dsi_dcs_write - send DCS write command
  * @dsi: DSI device
- * @channel: virtual channel
  * @data: pointer to the command followed by parameters
  * @len: length of @data
  */
-ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, unsigned int channel,
-			   const void *data, size_t len)
+ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, const void *data,
+			    size_t len)
 {
 	const struct mipi_dsi_host_ops *ops = dsi->host->ops;
 	struct mipi_dsi_msg msg = {
-		.channel = channel,
+		.channel = dsi->channel,
 		.tx_buf = data,
 		.tx_len = len
 	};
@@ -239,19 +238,18 @@ EXPORT_SYMBOL(mipi_dsi_dcs_write);
 /**
  * mipi_dsi_dcs_read - send DCS read request command
  * @dsi: DSI device
- * @channel: virtual channel
  * @cmd: DCS read command
  * @data: pointer to read buffer
  * @len: length of @data
  *
  * Function returns number of read bytes or error code.
  */
-ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, unsigned int channel,
-			  u8 cmd, void *data, size_t len)
+ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, u8 cmd, void *data,
+			  size_t len)
 {
 	const struct mipi_dsi_host_ops *ops = dsi->host->ops;
 	struct mipi_dsi_msg msg = {
-		.channel = channel,
+		.channel = dsi->channel,
 		.type = MIPI_DSI_DCS_READ,
 		.tx_buf = &cmd,
 		.tx_len = 1,

drivers/gpu/drm/panel/panel-s6e8aa0.c

@@ -138,7 +138,7 @@ static void s6e8aa0_dcs_write(struct s6e8aa0 *ctx, const void *data, size_t len)
 	if (ctx->error < 0)
 		return;
 
-	ret = mipi_dsi_dcs_write(dsi, dsi->channel, data, len);
+	ret = mipi_dsi_dcs_write(dsi, data, len);
 	if (ret < 0) {
 		dev_err(ctx->dev, "error %zd writing dcs seq: %*ph\n", ret, len,
 			data);
@@ -154,7 +154,7 @@ static int s6e8aa0_dcs_read(struct s6e8aa0 *ctx, u8 cmd, void *data, size_t len)
 	if (ctx->error < 0)
 		return ctx->error;
 
-	ret = mipi_dsi_dcs_read(dsi, dsi->channel, cmd, data, len);
+	ret = mipi_dsi_dcs_read(dsi, cmd, data, len);
 	if (ret < 0) {
 		dev_err(ctx->dev, "error %d reading dcs seq(%#x)\n", ret, cmd);
 		ctx->error = ret;

include/drm/drm_mipi_dsi.h

@@ -127,10 +127,10 @@ struct mipi_dsi_device {
 
 int mipi_dsi_attach(struct mipi_dsi_device *dsi);
 int mipi_dsi_detach(struct mipi_dsi_device *dsi);
-ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, unsigned int channel,
-			   const void *data, size_t len);
-ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, unsigned int channel,
-			  u8 cmd, void *data, size_t len);
+ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, const void *data,
+			    size_t len);
+ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, u8 cmd, void *data,
+			  size_t len);
 
 /**
  * struct mipi_dsi_driver - DSI driver