rockchip: video: document externally visible functions for rk_vop

Documents the externally visible functions shared between the VOP
drivers for the RK3288 and RK3399.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/video/rockchip/rk_vop.h

@@ -25,8 +25,42 @@ struct rkvop_driverdata {
 	void (*set_pin_polarity)(struct udevice *, enum vop_modes, u32);
 };
 
+/**
+ * rk_vop_probe() - common probe implementation
+ *
+ * Performs the rk_display_init on each port-subnode until finding a
+ * working port (or returning an error if none of the ports could be
+ * successfully initialised).
+ *
+ * @dev:	device
+ * @return 0 if OK, -ve if something went wrong
+ */
 int rk_vop_probe(struct udevice *dev);
+
+/**
+ * rk_vop_bind() - common bind implementation
+ *
+ * Sets the plat->size field to the amount of memory to be reserved for
+ * the framebuffer: this is always
+ *     (32 BPP) x VIDEO_ROCKCHIP_MAX_XRES x VIDEO_ROCKCHIP_MAX_YRES
+ *
+ * @dev:	device
+ * @return 0 (always OK)
+ */
 int rk_vop_bind(struct udevice *dev);
+
+/**
+ * rk_vop_probe_regulators() - probe (autoset + enable) regulators
+ *
+ * Probes a list of regulators by performing autoset and enable
+ * operations on them.  The list of regulators is an array of string
+ * pointers and any individual regulator-probe may fail without
+ * counting as an error.
+ *
+ * @dev:	device
+ * @names:	array of string-pointers to regulator names to probe
+ * @cnt:	number of elements in the 'names' array
+ */
 void rk_vop_probe_regulators(struct udevice *dev,
 			     const char * const *names, int cnt);