diff options
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/usb/endpoint.c | 58 |
1 files changed, 33 insertions, 25 deletions
diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c index 83a36d0d2a2d..e6906901debb 100644 --- a/sound/usb/endpoint.c +++ b/sound/usb/endpoint.c @@ -40,25 +40,26 @@ * 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. */ /* @@ -120,7 +121,7 @@ static const char *usb_error_string(int err) /** * 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. @@ -278,17 +279,18 @@ static inline void prepare_inbound_urb(struct snd_usb_endpoint *ep, } /* - * 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) { @@ -391,7 +393,7 @@ exit_clear: } /** - * 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 @@ -745,11 +747,14 @@ out_of_memory: } /** - * 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. */ @@ -807,7 +812,7 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep, * @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(). @@ -840,7 +845,8 @@ int snd_usb_endpoint_start(struct snd_usb_endpoint *ep) /* * 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); @@ -892,7 +898,7 @@ __error: * * 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(). */ @@ -994,7 +1000,8 @@ int snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep) 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 * @@ -1032,8 +1039,9 @@ void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep, /* * 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) { @@ -1063,8 +1071,8 @@ void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep, /* * 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; |