Index: uspace/lib/usbhost/include/usb/host/hcd.h
===================================================================
--- uspace/lib/usbhost/include/usb/host/hcd.h	(revision 54006064e13355076ae31f1cc5bb69a5056942c6)
+++ uspace/lib/usbhost/include/usb/host/hcd.h	(revision 4dfc905860c1e80378dde24f172dfa72c8133de8)
@@ -38,4 +38,5 @@
 #include <assert.h>
 #include <usbhc_iface.h>
+
 #include <usb/host/usb_device_manager.h>
 #include <usb/host/usb_endpoint_manager.h>
@@ -44,14 +45,27 @@
 typedef struct hcd hcd_t;
 
+/** Generic host controller driver structure. */
 struct hcd {
+	/** Device manager storing handles and addresses. */
 	usb_device_manager_t dev_manager;
+	/** Endpoint manager. */
 	usb_endpoint_manager_t ep_manager;
+
+	/** Device specific driver data. */
 	void *private_data;
-
+	/** Transfer scheduling, implement in device driver. */
 	int (*schedule)(hcd_t *, usb_transfer_batch_t *);
+	/** Hook called upon registering new endpoint. */
 	int (*ep_add_hook)(hcd_t *, endpoint_t *);
+	/** Hook called upon removing of an endpoint. */
 	void (*ep_remove_hook)(hcd_t *, endpoint_t *);
 };
 /*----------------------------------------------------------------------------*/
+/** Initialize hcd_t structure.
+ * Initializes device and endpoint managers. Sets data nd hook pointer to NULL.
+ * @param hcd hcd_t structure to initialize, non-null.
+ * @param bandwidth Available bandwidth, passed to endpoint manager.
+ * @param bw_count Bandwidth compute function, passed to endpoint manager.
+ */
 static inline void hcd_init(hcd_t *hcd, size_t bandwidth,
     size_t (*bw_count)(usb_speed_t, usb_transfer_type_t, size_t, size_t))
@@ -60,8 +74,17 @@
 	usb_device_manager_init(&hcd->dev_manager);
 	usb_endpoint_manager_init(&hcd->ep_manager, bandwidth, bw_count);
+	hcd->private_data = NULL;
+	hcd->schedule = NULL;
+	hcd->ep_add_hook = NULL;
+	hcd->ep_remove_hook = NULL;
 }
 /*----------------------------------------------------------------------------*/
-static inline void reset_ep_if_need(
-    hcd_t *hcd, usb_target_t target, const char* setup_data)
+/** Check registered endpoints and reset toggle bit if necessary.
+ * @param hcd hcd_t structure, non-null.
+ * @param target Control communication target.
+ * @param setup_data Setup packet of the control communication.
+ */
+static inline void reset_ep_if_need(hcd_t *hcd, usb_target_t target,
+    const char setup_data[8])
 {
 	assert(hcd);
@@ -70,4 +93,8 @@
 }
 /*----------------------------------------------------------------------------*/
+/** Data retrieve wrapper.
+ * @param fun ddf function, non-null.
+ * @return pointer cast to hcd_t*.
+ */
 static inline hcd_t * fun_to_hcd(ddf_fun_t *fun)
 {