drm/dsi: Introduce packet format helpers

Add two helpers, mipi_dsi_packet_format_is_{short,long}(), that help in
determining the format of a packet.
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/drm_mipi_dsi.c

@@ -198,6 +198,73 @@ int mipi_dsi_detach(struct mipi_dsi_device *dsi)
 }
 EXPORT_SYMBOL(mipi_dsi_detach);
 
+/**
+ * mipi_dsi_packet_format_is_short - check if a packet is of the short format
+ * @type: MIPI DSI data type of the packet
+ *
+ * Return: true if the packet for the given data type is a short packet, false
+ * otherwise.
+ */
+bool mipi_dsi_packet_format_is_short(u8 type)
+{
+	switch (type) {
+	case MIPI_DSI_V_SYNC_START:
+	case MIPI_DSI_V_SYNC_END:
+	case MIPI_DSI_H_SYNC_START:
+	case MIPI_DSI_H_SYNC_END:
+	case MIPI_DSI_END_OF_TRANSMISSION:
+	case MIPI_DSI_COLOR_MODE_OFF:
+	case MIPI_DSI_COLOR_MODE_ON:
+	case MIPI_DSI_SHUTDOWN_PERIPHERAL:
+	case MIPI_DSI_TURN_ON_PERIPHERAL:
+	case MIPI_DSI_GENERIC_SHORT_WRITE_0_PARAM:
+	case MIPI_DSI_GENERIC_SHORT_WRITE_1_PARAM:
+	case MIPI_DSI_GENERIC_SHORT_WRITE_2_PARAM:
+	case MIPI_DSI_GENERIC_READ_REQUEST_0_PARAM:
+	case MIPI_DSI_GENERIC_READ_REQUEST_1_PARAM:
+	case MIPI_DSI_GENERIC_READ_REQUEST_2_PARAM:
+	case MIPI_DSI_DCS_SHORT_WRITE:
+	case MIPI_DSI_DCS_SHORT_WRITE_PARAM:
+	case MIPI_DSI_DCS_READ:
+	case MIPI_DSI_SET_MAXIMUM_RETURN_PACKET_SIZE:
+		return true;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL(mipi_dsi_packet_format_is_short);
+
+/**
+ * mipi_dsi_packet_format_is_long - check if a packet is of the long format
+ * @type: MIPI DSI data type of the packet
+ *
+ * Return: true if the packet for the given data type is a long packet, false
+ * otherwise.
+ */
+bool mipi_dsi_packet_format_is_long(u8 type)
+{
+	switch (type) {
+	case MIPI_DSI_NULL_PACKET:
+	case MIPI_DSI_BLANKING_PACKET:
+	case MIPI_DSI_GENERIC_LONG_WRITE:
+	case MIPI_DSI_DCS_LONG_WRITE:
+	case MIPI_DSI_LOOSELY_PACKED_PIXEL_STREAM_YCBCR20:
+	case MIPI_DSI_PACKED_PIXEL_STREAM_YCBCR24:
+	case MIPI_DSI_PACKED_PIXEL_STREAM_YCBCR16:
+	case MIPI_DSI_PACKED_PIXEL_STREAM_30:
+	case MIPI_DSI_PACKED_PIXEL_STREAM_36:
+	case MIPI_DSI_PACKED_PIXEL_STREAM_YCBCR12:
+	case MIPI_DSI_PACKED_PIXEL_STREAM_16:
+	case MIPI_DSI_PACKED_PIXEL_STREAM_18:
+	case MIPI_DSI_PIXEL_STREAM_3BYTE_18:
+	case MIPI_DSI_PACKED_PIXEL_STREAM_24:
+		return true;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL(mipi_dsi_packet_format_is_long);
+
 /**
  * mipi_dsi_dcs_write - send DCS write command
  * @dsi: DSI device

include/drm/drm_mipi_dsi.h

@@ -43,6 +43,9 @@ struct mipi_dsi_msg {
 	void *rx_buf;
 };
 
+bool mipi_dsi_packet_format_is_short(u8 type);
+bool mipi_dsi_packet_format_is_long(u8 type);
+
 /**
  * struct mipi_dsi_host_ops - DSI bus operations
  * @attach: attach DSI device to DSI host