Commit 07a5e9d4 authored by Daniel Mack's avatar Daniel Mack Committed by Takashi Iwai
Browse files

ALSA: snd-usb: fix some typos in endpoint.c documentation



Also be more specific about some details while at it.
Signed-off-by: default avatarDaniel Mack <zonque@gmail.com>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent e9f66d9b
......@@ -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 @@ static void snd_complete_urb(struct urb *urb)
}
/**
* 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 @@ static int sync_ep_set_params(struct snd_usb_endpoint *ep,
}
/**
* 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 @@ int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
*
* 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;
......
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