/* Return: The number of bytes read or a negative error code on failure.  */
ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, u8 cmd, void *data, size_t len)
/* Return: The number of bytes read or a negative error code on failure.  */
ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, u8 cmd, void *data, size_t len)
{
	struct mipi_dsi_msg msg = {
		.channel = dsi->channel,
		.type = MIPI_DSI_DCS_READ,
		.tx_buf = &cmd,
		.tx_len = 1,
		.rx_buf = data,
		.rx_len = len
	};
	return mipi_dsi_device_transfer(dsi, &msg);
}