drm/dsi: Add to DocBook documentation

Integrate the MIPI DSI helpers into DocBook and clean up various
kerneldoc warnings. Also add a brief DOC section and clarify some
aspects of the mipi_dsi_host struct's .transfer() operation.

Acked-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Documentation/DocBook/drm.tmpl

@@ -2341,6 +2341,12 @@ void intel_crt_init(struct drm_device *dev)
 !Pdrivers/gpu/drm/drm_dp_mst_topology.c dp mst helper
 !Iinclude/drm/drm_dp_mst_helper.h
 !Edrivers/gpu/drm/drm_dp_mst_topology.c
+    </sect2>
+    <sect2>
+      <title>MIPI DSI Helper Functions Reference</title>
+!Pdrivers/gpu/drm/drm_mipi_dsi.c dsi helpers
+!Iinclude/drm/drm_mipi_dsi.h
+!Edrivers/gpu/drm/drm_mipi_dsi.c
     </sect2>
     <sect2>
       <title>EDID Helper Functions Reference</title>

drivers/gpu/drm/drm_mipi_dsi.c

@@ -35,6 +35,16 @@
 
 #include <video/mipi_display.h>
 
+/**
+ * DOC: dsi helpers
+ *
+ * These functions contain some common logic and helpers to deal with MIPI DSI
+ * peripherals.
+ *
+ * Helpers are provided for a number of standard MIPI DSI command as well as a
+ * subset of the MIPI DCS command set.
+ */
+
 static int mipi_dsi_device_match(struct device *dev, struct device_driver *drv)
 {
 	return of_driver_match_device(dev, drv);
@@ -699,8 +709,10 @@ static void mipi_dsi_drv_shutdown(struct device *dev)
 }
 
 /**
- * mipi_dsi_driver_register - register a driver for DSI devices
+ * mipi_dsi_driver_register() - register a driver for DSI devices
  * @drv: DSI driver structure
+ *
+ * Return: 0 on success or a negative error code on failure.
  */
 int mipi_dsi_driver_register(struct mipi_dsi_driver *drv)
 {
@@ -717,8 +729,10 @@ int mipi_dsi_driver_register(struct mipi_dsi_driver *drv)
 EXPORT_SYMBOL(mipi_dsi_driver_register);
 
 /**
- * mipi_dsi_driver_unregister - unregister a driver for DSI devices
+ * mipi_dsi_driver_unregister() - unregister a driver for DSI devices
  * @drv: DSI driver structure
+ *
+ * Return: 0 on success or a negative error code on failure.
  */
 void mipi_dsi_driver_unregister(struct mipi_dsi_driver *drv)
 {

include/drm/drm_mipi_dsi.h

@@ -26,6 +26,7 @@ struct mipi_dsi_device;
  * struct mipi_dsi_msg - read/write DSI buffer
  * @channel: virtual channel id
  * @type: payload data type
+ * @flags: flags controlling this message transmission
  * @tx_len: length of @tx_buf
  * @tx_buf: data to be written
  * @rx_len: length of @rx_buf
@@ -68,8 +69,19 @@ int mipi_dsi_create_packet(struct mipi_dsi_packet *packet,
  * struct mipi_dsi_host_ops - DSI bus operations
  * @attach: attach DSI device to DSI host
  * @detach: detach DSI device from DSI host
- * @transfer: send and/or receive DSI packet, return number of received bytes,
- * 	      or error
+ * @transfer: transmit a DSI packet
+ *
+ * DSI packets transmitted by .transfer() are passed in as mipi_dsi_msg
+ * structures. This structure contains information about the type of packet
+ * being transmitted as well as the transmit and receive buffers. When an
+ * error is encountered during transmission, this function will return a
+ * negative error code. On success it shall return the number of bytes
+ * transmitted for write packets or the number of bytes received for read
+ * packets.
+ *
+ * Note that typically DSI packet transmission is atomic, so the .transfer()
+ * function will seldomly return anything other than the number of bytes
+ * contained in the transmit buffer on success.
  */
 struct mipi_dsi_host_ops {
 	int (*attach)(struct mipi_dsi_host *host,