* USB endpoint and its streaming.
*
* There are functions to activate and deactivate the streaming URBs and
- * optinal callbacks to let the pcm logic handle the actual content of the
+ * optional callbacks to let the pcm logic handle the actual content of the
* packets for playback and record. Thus, the bus streaming and the audio
* handlers are fully decoupled.
*
- * There are two different types of endpoints in for audio applications.
+ * There are two different types of endpoints in audio applications.
*
* SND_USB_ENDPOINT_TYPE_DATA handles full audio data payload for both
* inbound and outbound traffic.
*
- * SND_USB_ENDPOINT_TYPE_SYNC are for inbound traffic only and expect the
- * payload to carry Q16.16 formatted sync information (3 or 4 bytes).
+ * SND_USB_ENDPOINT_TYPE_SYNC endpoints are for inbound traffic only and
+ * expect the payload to carry Q10.14 / Q16.16 formatted sync information
+ * (3 or 4 bytes).
*
- * Each endpoint has to be configured (by calling
- * snd_usb_endpoint_set_params()) before it can be used.
+ * Each endpoint has to be configured prior to being used by calling
+ * snd_usb_endpoint_set_params().
*
* The model incorporates a reference counting, so that multiple users
* can call snd_usb_endpoint_start() and snd_usb_endpoint_stop(), and
* only the first user will effectively start the URBs, and only the last
- * one will tear them down again.
+ * one to stop it will tear the URBs down again.
*/
/*
/**
* snd_usb_endpoint_implicit_feedback_sink: Report endpoint usage type
*
- * @ep: The endpoint
+ * @ep: The snd_usb_endpoint
*
* Determine whether an endpoint is driven by an implicit feedback
* data endpoint source.
}
/*
- * Send output urbs that have been prepared previously. Urbs are dequeued
+ * Send output urbs that have been prepared previously. URBs are dequeued
* from ep->ready_playback_urbs and in case there there aren't any available
* or there are no packets that have been prepared, this function does
* nothing.
*
- * The reason why the functionality of sending and preparing urbs is separated
- * is that host controllers don't guarantee an ordering in returing inbound
- * and outbound packets to their submitters.
+ * The reason why the functionality of sending and preparing URBs is separated
+ * is that host controllers don't guarantee the order in which they return
+ * inbound and outbound packets to their submitters.
*
* This function is only used for implicit feedback endpoints. For endpoints
- * driven by sync endpoints, urbs are submitted from their completion handler.
+ * driven by dedicated sync endpoints, URBs are immediately re-submitted
+ * from their completion handler.
*/
static void queue_pending_output_urbs(struct snd_usb_endpoint *ep)
{
}
/**
- * snd_usb_add_endpoint: Add an endpoint to an audio chip
+ * snd_usb_add_endpoint: Add an endpoint to an USB audio chip
*
* @chip: The chip
* @alts: The USB host interface
}
/**
- * snd_usb_endpoint_set_params: configure an snd_endpoint
+ * snd_usb_endpoint_set_params: configure an snd_usb_endpoint
*
- * @ep: the endpoint to configure
+ * @ep: the snd_usb_endpoint to configure
+ * @hw_params: the hardware parameters
+ * @fmt: the USB audio format information
+ * @sync_ep: the sync endpoint to use, if any
*
- * Determine the number of of URBs to be used on this endpoint.
+ * Determine the number of URBs to be used on this endpoint.
* An endpoint must be configured before it can be started.
* An endpoint that is already running can not be reconfigured.
*/
* @ep: the endpoint to start
*
* A call to this function will increment the use count of the endpoint.
- * In case this not already running, the URBs for this endpoint will be
+ * In case it is not already running, the URBs for this endpoint will be
* submitted. Otherwise, this function does nothing.
*
* Must be balanced to calls of snd_usb_endpoint_stop().
/*
* If this endpoint has a data endpoint as implicit feedback source,
* don't start the urbs here. Instead, mark them all as available,
- * wait for the record urbs to arrive and queue from that context.
+ * wait for the record urbs to return and queue the playback urbs
+ * from that context.
*/
set_bit(EP_FLAG_RUNNING, &ep->flags);
*
* A call to this function will decrement the use count of the endpoint.
* In case the last user has requested the endpoint stop, the URBs will
- * actually deactivated.
+ * actually be deactivated.
*
* Must be balanced to calls of snd_usb_endpoint_start().
*/
return -EBUSY;
}
-/** snd_usb_endpoint_free: Free the resources of an snd_usb_endpoint
+/**
+ * snd_usb_endpoint_free: Free the resources of an snd_usb_endpoint
*
* @ep: the list header of the endpoint to free
*
/*
* In case the endpoint is operating in implicit feedback mode, prepare
- * and a new outbound URB that has the same layout as the received
- * packet and add it to the list of pending urbs.
+ * a new outbound URB that has the same layout as the received packet
+ * and add it to the list of pending urbs. queue_pending_output_urbs()
+ * will take care of them later.
*/
if (snd_usb_endpoint_implict_feedback_sink(ep) &&
ep->use_count != 0) {
/*
* Iterate through the inbound packet and prepare the lengths
* for the output packet. The OUT packet we are about to send
- * will have the same amount of payload than the IN packet we
- * just received.
+ * will have the same amount of payload bytes than the IN
+ * packet we just received.
*/
out_packet->packets = in_ctx->packets;
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