endpoint.c 40.5 KB
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
 */

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#include <linux/gfp.h>
#include <linux/init.h>
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#include <linux/ratelimit.h>
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#include <linux/usb.h>
#include <linux/usb/audio.h>
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#include <linux/slab.h>
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#include <sound/core.h>
#include <sound/pcm.h>
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#include <sound/pcm_params.h>
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#include "usbaudio.h"
#include "helper.h"
#include "card.h"
#include "endpoint.h"
#include "pcm.h"
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#include "quirks.h"
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#define EP_FLAG_RUNNING		1
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#define EP_FLAG_STOPPING	2
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/*
 * snd_usb_endpoint is a model that abstracts everything related to an
 * USB endpoint and its streaming.
 *
 * There are functions to activate and deactivate the streaming URBs and
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 * optional callbacks to let the pcm logic handle the actual content of the
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 * packets for playback and record. Thus, the bus streaming and the audio
 * handlers are fully decoupled.
 *
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 * There are two different types of endpoints in audio applications.
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 *
 * SND_USB_ENDPOINT_TYPE_DATA handles full audio data payload for both
 * inbound and outbound traffic.
 *
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 * 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).
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 *
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 * Each endpoint has to be configured prior to being used by calling
 * snd_usb_endpoint_set_params().
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 *
 * 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
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 * one to stop it will tear the URBs down again.
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 */

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/*
 * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
 * this will overflow at approx 524 kHz
 */
static inline unsigned get_usb_full_speed_rate(unsigned int rate)
{
	return ((rate << 13) + 62) / 125;
}

/*
 * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
 * this will overflow at approx 4 MHz
 */
static inline unsigned get_usb_high_speed_rate(unsigned int rate)
{
	return ((rate << 10) + 62) / 125;
}

/*
 * release a urb data
 */
static void release_urb_ctx(struct snd_urb_ctx *u)
{
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	if (u->buffer_size)
		usb_free_coherent(u->ep->chip->dev, u->buffer_size,
				  u->urb->transfer_buffer,
				  u->urb->transfer_dma);
	usb_free_urb(u->urb);
	u->urb = NULL;
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}

static const char *usb_error_string(int err)
{
	switch (err) {
	case -ENODEV:
		return "no device";
	case -ENOENT:
		return "endpoint not enabled";
	case -EPIPE:
		return "endpoint stalled";
	case -ENOSPC:
		return "not enough bandwidth";
	case -ESHUTDOWN:
		return "device disabled";
	case -EHOSTUNREACH:
		return "device suspended";
	case -EINVAL:
	case -EAGAIN:
	case -EFBIG:
	case -EMSGSIZE:
		return "internal error";
	default:
		return "unknown error";
	}
}

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/**
 * snd_usb_endpoint_implicit_feedback_sink: Report endpoint usage type
 *
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 * @ep: The snd_usb_endpoint
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 *
 * Determine whether an endpoint is driven by an implicit feedback
 * data endpoint source.
 */
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int snd_usb_endpoint_implicit_feedback_sink(struct snd_usb_endpoint *ep)
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{
	return  ep->sync_master &&
		ep->sync_master->type == SND_USB_ENDPOINT_TYPE_DATA &&
		ep->type == SND_USB_ENDPOINT_TYPE_DATA &&
		usb_pipeout(ep->pipe);
}

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/*
 * For streaming based on information derived from sync endpoints,
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 * prepare_outbound_urb_sizes() will call slave_next_packet_size() to
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 * determine the number of samples to be sent in the next packet.
 *
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 * For implicit feedback, slave_next_packet_size() is unused.
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 */
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int snd_usb_endpoint_slave_next_packet_size(struct snd_usb_endpoint *ep)
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{
	unsigned long flags;
	int ret;

	if (ep->fill_max)
		return ep->maxframesize;

	spin_lock_irqsave(&ep->lock, flags);
	ep->phase = (ep->phase & 0xffff)
		+ (ep->freqm << ep->datainterval);
	ret = min(ep->phase >> 16, ep->maxframesize);
	spin_unlock_irqrestore(&ep->lock, flags);

	return ret;
}

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/*
 * For adaptive and synchronous endpoints, prepare_outbound_urb_sizes()
 * will call next_packet_size() to determine the number of samples to be
 * sent in the next packet.
 */
int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep)
{
	int ret;

	if (ep->fill_max)
		return ep->maxframesize;

	ep->sample_accum += ep->sample_rem;
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	if (ep->sample_accum >= ep->pps) {
		ep->sample_accum -= ep->pps;
		ret = ep->packsize[1];
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	} else {
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		ret = ep->packsize[0];
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	}

	return ret;
}

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static void retire_outbound_urb(struct snd_usb_endpoint *ep,
				struct snd_urb_ctx *urb_ctx)
{
	if (ep->retire_data_urb)
		ep->retire_data_urb(ep->data_subs, urb_ctx->urb);
}

static void retire_inbound_urb(struct snd_usb_endpoint *ep,
			       struct snd_urb_ctx *urb_ctx)
{
	struct urb *urb = urb_ctx->urb;

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	if (unlikely(ep->skip_packets > 0)) {
		ep->skip_packets--;
		return;
	}

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	if (ep->sync_slave)
		snd_usb_handle_sync_urb(ep->sync_slave, ep, urb);

	if (ep->retire_data_urb)
		ep->retire_data_urb(ep->data_subs, urb);
}

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static void prepare_silent_urb(struct snd_usb_endpoint *ep,
			       struct snd_urb_ctx *ctx)
{
	struct urb *urb = ctx->urb;
	unsigned int offs = 0;
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	unsigned int extra = 0;
	__le32 packet_length;
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	int i;

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	/* For tx_length_quirk, put packet length at start of packet */
	if (ep->chip->tx_length_quirk)
		extra = sizeof(packet_length);

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	for (i = 0; i < ctx->packets; ++i) {
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		unsigned int offset;
		unsigned int length;
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		int counts;

		if (ctx->packet_size[i])
			counts = ctx->packet_size[i];
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		else if (ep->sync_master)
			counts = snd_usb_endpoint_slave_next_packet_size(ep);
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		else
			counts = snd_usb_endpoint_next_packet_size(ep);

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		length = counts * ep->stride; /* number of silent bytes */
		offset = offs * ep->stride + extra * i;
		urb->iso_frame_desc[i].offset = offset;
		urb->iso_frame_desc[i].length = length + extra;
		if (extra) {
			packet_length = cpu_to_le32(length);
			memcpy(urb->transfer_buffer + offset,
			       &packet_length, sizeof(packet_length));
		}
		memset(urb->transfer_buffer + offset + extra,
		       ep->silence_value, length);
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		offs += counts;
	}

	urb->number_of_packets = ctx->packets;
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	urb->transfer_buffer_length = offs * ep->stride + ctx->packets * extra;
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}

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/*
 * Prepare a PLAYBACK urb for submission to the bus.
 */
static void prepare_outbound_urb(struct snd_usb_endpoint *ep,
				 struct snd_urb_ctx *ctx)
{
	struct urb *urb = ctx->urb;
	unsigned char *cp = urb->transfer_buffer;

	urb->dev = ep->chip->dev; /* we need to set this at each time */

	switch (ep->type) {
	case SND_USB_ENDPOINT_TYPE_DATA:
		if (ep->prepare_data_urb) {
			ep->prepare_data_urb(ep->data_subs, urb);
		} else {
			/* no data provider, so send silence */
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			prepare_silent_urb(ep, ctx);
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		}
		break;

	case SND_USB_ENDPOINT_TYPE_SYNC:
		if (snd_usb_get_speed(ep->chip->dev) >= USB_SPEED_HIGH) {
			/*
			 * fill the length and offset of each urb descriptor.
			 * the fixed 12.13 frequency is passed as 16.16 through the pipe.
			 */
			urb->iso_frame_desc[0].length = 4;
			urb->iso_frame_desc[0].offset = 0;
			cp[0] = ep->freqn;
			cp[1] = ep->freqn >> 8;
			cp[2] = ep->freqn >> 16;
			cp[3] = ep->freqn >> 24;
		} else {
			/*
			 * fill the length and offset of each urb descriptor.
			 * the fixed 10.14 frequency is passed through the pipe.
			 */
			urb->iso_frame_desc[0].length = 3;
			urb->iso_frame_desc[0].offset = 0;
			cp[0] = ep->freqn >> 2;
			cp[1] = ep->freqn >> 10;
			cp[2] = ep->freqn >> 18;
		}

		break;
	}
}

/*
 * Prepare a CAPTURE or SYNC urb for submission to the bus.
 */
static inline void prepare_inbound_urb(struct snd_usb_endpoint *ep,
				       struct snd_urb_ctx *urb_ctx)
{
	int i, offs;
	struct urb *urb = urb_ctx->urb;

	urb->dev = ep->chip->dev; /* we need to set this at each time */

	switch (ep->type) {
	case SND_USB_ENDPOINT_TYPE_DATA:
		offs = 0;
		for (i = 0; i < urb_ctx->packets; i++) {
			urb->iso_frame_desc[i].offset = offs;
			urb->iso_frame_desc[i].length = ep->curpacksize;
			offs += ep->curpacksize;
		}

		urb->transfer_buffer_length = offs;
		urb->number_of_packets = urb_ctx->packets;
		break;

	case SND_USB_ENDPOINT_TYPE_SYNC:
		urb->iso_frame_desc[0].length = min(4u, ep->syncmaxsize);
		urb->iso_frame_desc[0].offset = 0;
		break;
	}
}

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/*
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 * Send output urbs that have been prepared previously. URBs are dequeued
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 * from ep->ready_playback_urbs and in case there aren't any available
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 * or there are no packets that have been prepared, this function does
 * nothing.
 *
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 * 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.
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 *
 * This function is only used for implicit feedback endpoints. For endpoints
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 * driven by dedicated sync endpoints, URBs are immediately re-submitted
 * from their completion handler.
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 */
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static void queue_pending_output_urbs(struct snd_usb_endpoint *ep)
{
	while (test_bit(EP_FLAG_RUNNING, &ep->flags)) {

		unsigned long flags;
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		struct snd_usb_packet_info *packet;
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		struct snd_urb_ctx *ctx = NULL;
		int err, i;

		spin_lock_irqsave(&ep->lock, flags);
		if (ep->next_packet_read_pos != ep->next_packet_write_pos) {
			packet = ep->next_packet + ep->next_packet_read_pos;
			ep->next_packet_read_pos++;
			ep->next_packet_read_pos %= MAX_URBS;

			/* take URB out of FIFO */
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			if (!list_empty(&ep->ready_playback_urbs)) {
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				ctx = list_first_entry(&ep->ready_playback_urbs,
					       struct snd_urb_ctx, ready_list);
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				list_del_init(&ctx->ready_list);
			}
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		}
		spin_unlock_irqrestore(&ep->lock, flags);

		if (ctx == NULL)
			return;

		/* copy over the length information */
		for (i = 0; i < packet->packets; i++)
			ctx->packet_size[i] = packet->packet_size[i];

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		/* call the data handler to fill in playback data */
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		prepare_outbound_urb(ep, ctx);

		err = usb_submit_urb(ctx->urb, GFP_ATOMIC);
		if (err < 0)
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			usb_audio_err(ep->chip,
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				      "Unable to submit urb #%d: %d at %s\n",
				      ctx->index, err, __func__);
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		else
			set_bit(ctx->index, &ep->active_mask);
	}
}

/*
 * complete callback for urbs
 */
static void snd_complete_urb(struct urb *urb)
{
	struct snd_urb_ctx *ctx = urb->context;
	struct snd_usb_endpoint *ep = ctx->ep;
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	struct snd_pcm_substream *substream;
	unsigned long flags;
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	int err;

	if (unlikely(urb->status == -ENOENT ||		/* unlinked */
		     urb->status == -ENODEV ||		/* device removed */
		     urb->status == -ECONNRESET ||	/* unlinked */
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		     urb->status == -ESHUTDOWN))	/* device disabled */
		goto exit_clear;
	/* device disconnected */
	if (unlikely(atomic_read(&ep->chip->shutdown)))
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		goto exit_clear;

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	if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
		goto exit_clear;

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	if (usb_pipeout(ep->pipe)) {
		retire_outbound_urb(ep, ctx);
		/* can be stopped during retire callback */
		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
			goto exit_clear;

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		if (snd_usb_endpoint_implicit_feedback_sink(ep)) {
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			spin_lock_irqsave(&ep->lock, flags);
			list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
			spin_unlock_irqrestore(&ep->lock, flags);
			queue_pending_output_urbs(ep);

			goto exit_clear;
		}

		prepare_outbound_urb(ep, ctx);
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		/* can be stopped during prepare callback */
		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
			goto exit_clear;
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	} else {
		retire_inbound_urb(ep, ctx);
		/* can be stopped during retire callback */
		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
			goto exit_clear;

		prepare_inbound_urb(ep, ctx);
	}

	err = usb_submit_urb(urb, GFP_ATOMIC);
	if (err == 0)
		return;

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	usb_audio_err(ep->chip, "cannot submit urb (err = %d)\n", err);
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	if (ep->data_subs && ep->data_subs->pcm_substream) {
		substream = ep->data_subs->pcm_substream;
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		snd_pcm_stop_xrun(substream);
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	}
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exit_clear:
	clear_bit(ctx->index, &ep->active_mask);
}

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/*
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 * Get the existing endpoint object corresponding EP
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 * Returns NULL if not present.
 */
struct snd_usb_endpoint *
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snd_usb_get_endpoint(struct snd_usb_audio *chip, int ep_num)
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{
	struct snd_usb_endpoint *ep;

	list_for_each_entry(ep, &chip->ep_list, list) {
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		if (ep->ep_num == ep_num)
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			return ep;
	}
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	return NULL;
}

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#define ep_type_name(type) \
	(type == SND_USB_ENDPOINT_TYPE_DATA ? "data" : "sync")

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/**
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 * snd_usb_add_endpoint: Add an endpoint to an USB audio chip
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 *
 * @chip: The chip
 * @ep_num: The number of the endpoint to use
 * @type: SND_USB_ENDPOINT_TYPE_DATA or SND_USB_ENDPOINT_TYPE_SYNC
 *
 * If the requested endpoint has not been added to the given chip before,
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 * a new instance is created.
 *
 * Returns zero on success or a negative error code.
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 *
 * New endpoints will be added to chip->ep_list and must be freed by
 * calling snd_usb_endpoint_free().
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 *
 * For SND_USB_ENDPOINT_TYPE_SYNC, the caller needs to guarantee that
 * bNumEndpoints > 1 beforehand.
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 */
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int snd_usb_add_endpoint(struct snd_usb_audio *chip, int ep_num, int type)
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{
	struct snd_usb_endpoint *ep;
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	bool is_playback;
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	ep = snd_usb_get_endpoint(chip, ep_num);
	if (ep)
		return 0;
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	usb_audio_dbg(chip, "Creating new %s endpoint #%x\n",
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		      ep_type_name(type),
		      ep_num);
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	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
	if (!ep)
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		return -ENOMEM;
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	ep->chip = chip;
	spin_lock_init(&ep->lock);
	ep->type = type;
	ep->ep_num = ep_num;
	INIT_LIST_HEAD(&ep->ready_playback_urbs);

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	is_playback = ((ep_num & USB_ENDPOINT_DIR_MASK) == USB_DIR_OUT);
	ep_num &= USB_ENDPOINT_NUMBER_MASK;
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	if (is_playback)
		ep->pipe = usb_sndisocpipe(chip->dev, ep_num);
	else
		ep->pipe = usb_rcvisocpipe(chip->dev, ep_num);

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	list_add_tail(&ep->list, &chip->ep_list);
	return 0;
}

/* Set up syncinterval and maxsyncsize for a sync EP */
void snd_usb_endpoint_set_syncinterval(struct snd_usb_audio *chip,
				       struct snd_usb_endpoint *ep,
				       struct usb_host_interface *alts)
{
	struct usb_endpoint_descriptor *desc = get_endpoint(alts, 1);

	if (ep->type == SND_USB_ENDPOINT_TYPE_SYNC) {
		if (desc->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
		    desc->bRefresh >= 1 && desc->bRefresh <= 9)
			ep->syncinterval = desc->bRefresh;
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		else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL)
			ep->syncinterval = 1;
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		else if (desc->bInterval >= 1 && desc->bInterval <= 16)
			ep->syncinterval = desc->bInterval - 1;
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		else
			ep->syncinterval = 3;

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		ep->syncmaxsize = le16_to_cpu(desc->wMaxPacketSize);
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	}
}

/*
 *  wait until all urbs are processed.
 */
static int wait_clear_urbs(struct snd_usb_endpoint *ep)
{
	unsigned long end_time = jiffies + msecs_to_jiffies(1000);
	int alive;

	do {
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		alive = bitmap_weight(&ep->active_mask, ep->nurbs);
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		if (!alive)
			break;

		schedule_timeout_uninterruptible(1);
	} while (time_before(jiffies, end_time));

	if (alive)
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		usb_audio_err(ep->chip,
			"timeout: still %d active urbs on EP #%x\n",
			alive, ep->ep_num);
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	clear_bit(EP_FLAG_STOPPING, &ep->flags);
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	ep->data_subs = NULL;
	ep->sync_slave = NULL;
	ep->retire_data_urb = NULL;
	ep->prepare_data_urb = NULL;

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	return 0;
}

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/* sync the pending stop operation;
 * this function itself doesn't trigger the stop operation
 */
void snd_usb_endpoint_sync_pending_stop(struct snd_usb_endpoint *ep)
{
	if (ep && test_bit(EP_FLAG_STOPPING, &ep->flags))
		wait_clear_urbs(ep);
}

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/*
 * unlink active urbs.
 */
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static int deactivate_urbs(struct snd_usb_endpoint *ep, bool force)
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{
	unsigned int i;

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	if (!force && atomic_read(&ep->chip->shutdown)) /* to be sure... */
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		return -EBADFD;

	clear_bit(EP_FLAG_RUNNING, &ep->flags);

	INIT_LIST_HEAD(&ep->ready_playback_urbs);
	ep->next_packet_read_pos = 0;
	ep->next_packet_write_pos = 0;

	for (i = 0; i < ep->nurbs; i++) {
		if (test_bit(i, &ep->active_mask)) {
			if (!test_and_set_bit(i, &ep->unlink_mask)) {
				struct urb *u = ep->urb[i].urb;
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				usb_unlink_urb(u);
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			}
		}
	}

	return 0;
}

/*
 * release an endpoint's urbs
 */
static void release_urbs(struct snd_usb_endpoint *ep, int force)
{
	int i;

	/* route incoming urbs to nirvana */
	ep->retire_data_urb = NULL;
	ep->prepare_data_urb = NULL;

	/* stop urbs */
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	deactivate_urbs(ep, force);
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	wait_clear_urbs(ep);

	for (i = 0; i < ep->nurbs; i++)
		release_urb_ctx(&ep->urb[i]);

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	usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
			  ep->syncbuf, ep->sync_dma);
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	ep->syncbuf = NULL;
	ep->nurbs = 0;
}

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/*
 * Check data endpoint for format differences
 */
static bool check_ep_params(struct snd_usb_endpoint *ep,
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			    snd_pcm_format_t pcm_format,
			    unsigned int channels,
			    unsigned int period_bytes,
			    unsigned int frames_per_period,
			    unsigned int periods_per_buffer,
			    unsigned int rate,
			    struct audioformat *fmt,
			    struct snd_usb_endpoint *sync_ep)
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{
	unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
	unsigned int max_packs_per_period, urbs_per_period, urb_packs;
	unsigned int max_urbs;
	int frame_bits = snd_pcm_format_physical_width(pcm_format) * channels;
	int tx_length_quirk = (ep->chip->tx_length_quirk &&
			       usb_pipeout(ep->pipe));
	bool ret = 1;

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	/* matching with the saved parameters? */
	if (ep->cur_rate == rate &&
	    ep->cur_format == pcm_format &&
	    ep->cur_channels == channels &&
	    ep->cur_period_frames == frames_per_period &&
	    ep->cur_buffer_periods == periods_per_buffer)
		return true;

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	if (pcm_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
		/*
		 * When operating in DSD DOP mode, the size of a sample frame
		 * in hardware differs from the actual physical format width
		 * because we need to make room for the DOP markers.
		 */
		frame_bits += channels << 3;
	}

	ret = ret && (ep->datainterval == fmt->datainterval);
	ret = ret && (ep->stride == frame_bits >> 3);

	switch (pcm_format) {
	case SNDRV_PCM_FORMAT_U8:
		ret = ret && (ep->silence_value == 0x80);
		break;
	case SNDRV_PCM_FORMAT_DSD_U8:
	case SNDRV_PCM_FORMAT_DSD_U16_LE:
	case SNDRV_PCM_FORMAT_DSD_U32_LE:
	case SNDRV_PCM_FORMAT_DSD_U16_BE:
	case SNDRV_PCM_FORMAT_DSD_U32_BE:
		ret = ret && (ep->silence_value == 0x69);
		break;
	default:
		ret = ret && (ep->silence_value == 0);
	}

	/* assume max. frequency is 50% higher than nominal */
	ret = ret && (ep->freqmax == ep->freqn + (ep->freqn >> 1));
	/* Round up freqmax to nearest integer in order to calculate maximum
	 * packet size, which must represent a whole number of frames.
	 * This is accomplished by adding 0x0.ffff before converting the
	 * Q16.16 format into integer.
	 * In order to accurately calculate the maximum packet size when
	 * the data interval is more than 1 (i.e. ep->datainterval > 0),
	 * multiply by the data interval prior to rounding. For instance,
	 * a freqmax of 41 kHz will result in a max packet size of 6 (5.125)
	 * frames with a data interval of 1, but 11 (10.25) frames with a
	 * data interval of 2.
	 * (ep->freqmax << ep->datainterval overflows at 8.192 MHz for the
	 * maximum datainterval value of 3, at USB full speed, higher for
	 * USB high speed, noting that ep->freqmax is in units of
	 * frames per packet in Q16.16 format.)
	 */
	maxsize = (((ep->freqmax << ep->datainterval) + 0xffff) >> 16) *
			 (frame_bits >> 3);
	if (tx_length_quirk)
		maxsize += sizeof(__le32); /* Space for length descriptor */
	/* but wMaxPacketSize might reduce this */
	if (ep->maxpacksize && ep->maxpacksize < maxsize) {
		/* whatever fits into a max. size packet */
		unsigned int data_maxsize = maxsize = ep->maxpacksize;

		if (tx_length_quirk)
			/* Need to remove the length descriptor to calc freq */
			data_maxsize -= sizeof(__le32);
		ret = ret && (ep->freqmax == (data_maxsize / (frame_bits >> 3))
				<< (16 - ep->datainterval));
	}

	if (ep->fill_max)
		ret = ret && (ep->curpacksize == ep->maxpacksize);
	else
		ret = ret && (ep->curpacksize == maxsize);

	if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL) {
		packs_per_ms = 8 >> ep->datainterval;
		max_packs_per_urb = MAX_PACKS_HS;
	} else {
		packs_per_ms = 1;
		max_packs_per_urb = MAX_PACKS;
	}
	if (sync_ep && !snd_usb_endpoint_implicit_feedback_sink(ep))
		max_packs_per_urb = min(max_packs_per_urb,
					1U << sync_ep->syncinterval);
	max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);

	/*
	 * Capture endpoints need to use small URBs because there's no way
	 * to tell in advance where the next period will end, and we don't
	 * want the next URB to complete much after the period ends.
	 *
	 * Playback endpoints with implicit sync much use the same parameters
	 * as their corresponding capture endpoint.
	 */
	if (usb_pipein(ep->pipe) ||
			snd_usb_endpoint_implicit_feedback_sink(ep)) {

		urb_packs = packs_per_ms;
		/*
		 * Wireless devices can poll at a max rate of once per 4ms.
		 * For dataintervals less than 5, increase the packet count to
		 * allow the host controller to use bursting to fill in the
		 * gaps.
		 */
		if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_WIRELESS) {
			int interval = ep->datainterval;

			while (interval < 5) {
				urb_packs <<= 1;
				++interval;
			}
		}
		/* make capture URBs <= 1 ms and smaller than a period */
		urb_packs = min(max_packs_per_urb, urb_packs);
		while (urb_packs > 1 && urb_packs * maxsize >= period_bytes)
			urb_packs >>= 1;
		ret = ret && (ep->nurbs == MAX_URBS);

	/*
	 * Playback endpoints without implicit sync are adjusted so that
	 * a period fits as evenly as possible in the smallest number of
	 * URBs.  The total number of URBs is adjusted to the size of the
	 * ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
	 */
	} else {
		/* determine how small a packet can be */
		minsize = (ep->freqn >> (16 - ep->datainterval)) *
				(frame_bits >> 3);
		/* with sync from device, assume it can be 12% lower */
		if (sync_ep)
			minsize -= minsize >> 3;
		minsize = max(minsize, 1u);

		/* how many packets will contain an entire ALSA period? */
		max_packs_per_period = DIV_ROUND_UP(period_bytes, minsize);

		/* how many URBs will contain a period? */
		urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
				max_packs_per_urb);
		/* how many packets are needed in each URB? */
		urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);

		/* limit the number of frames in a single URB */
		ret = ret && (ep->max_urb_frames ==
			DIV_ROUND_UP(frames_per_period, urbs_per_period));

		/* try to use enough URBs to contain an entire ALSA buffer */
		max_urbs = min((unsigned) MAX_URBS,
				MAX_QUEUE * packs_per_ms / urb_packs);
		ret = ret && (ep->nurbs == min(max_urbs,
				urbs_per_period * periods_per_buffer));
	}

	ret = ret && (ep->datainterval == fmt->datainterval);
	ret = ret && (ep->maxpacksize == fmt->maxpacksize);
	ret = ret &&
		(ep->fill_max == !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX));

	return ret;
}

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810
/*
 * configure a data endpoint
 */
811
static int data_ep_set_params(struct snd_usb_endpoint *ep,
812
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814
			      snd_pcm_format_t pcm_format,
			      unsigned int channels,
			      unsigned int period_bytes,
815
816
			      unsigned int frames_per_period,
			      unsigned int periods_per_buffer,
817
818
819
			      struct audioformat *fmt,
			      struct snd_usb_endpoint *sync_ep)
{
820
821
822
	unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
	unsigned int max_packs_per_period, urbs_per_period, urb_packs;
	unsigned int max_urbs, i;
823
	int frame_bits = snd_pcm_format_physical_width(pcm_format) * channels;
824
825
	int tx_length_quirk = (ep->chip->tx_length_quirk &&
			       usb_pipeout(ep->pipe));
826

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835
	if (pcm_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
		/*
		 * When operating in DSD DOP mode, the size of a sample frame
		 * in hardware differs from the actual physical format width
		 * because we need to make room for the DOP markers.
		 */
		frame_bits += channels << 3;
	}

836
837
	ep->datainterval = fmt->datainterval;
	ep->stride = frame_bits >> 3;
838
839
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841
842
843
844
845
846
847
848
849
850
851
852

	switch (pcm_format) {
	case SNDRV_PCM_FORMAT_U8:
		ep->silence_value = 0x80;
		break;
	case SNDRV_PCM_FORMAT_DSD_U8:
	case SNDRV_PCM_FORMAT_DSD_U16_LE:
	case SNDRV_PCM_FORMAT_DSD_U32_LE:
	case SNDRV_PCM_FORMAT_DSD_U16_BE:
	case SNDRV_PCM_FORMAT_DSD_U32_BE:
		ep->silence_value = 0x69;
		break;
	default:
		ep->silence_value = 0;
	}
853

854
855
	/* assume max. frequency is 50% higher than nominal */
	ep->freqmax = ep->freqn + (ep->freqn >> 1);
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
	/* Round up freqmax to nearest integer in order to calculate maximum
	 * packet size, which must represent a whole number of frames.
	 * This is accomplished by adding 0x0.ffff before converting the
	 * Q16.16 format into integer.
	 * In order to accurately calculate the maximum packet size when
	 * the data interval is more than 1 (i.e. ep->datainterval > 0),
	 * multiply by the data interval prior to rounding. For instance,
	 * a freqmax of 41 kHz will result in a max packet size of 6 (5.125)
	 * frames with a data interval of 1, but 11 (10.25) frames with a
	 * data interval of 2.
	 * (ep->freqmax << ep->datainterval overflows at 8.192 MHz for the
	 * maximum datainterval value of 3, at USB full speed, higher for
	 * USB high speed, noting that ep->freqmax is in units of
	 * frames per packet in Q16.16 format.)
	 */
	maxsize = (((ep->freqmax << ep->datainterval) + 0xffff) >> 16) *
			 (frame_bits >> 3);
873
874
	if (tx_length_quirk)
		maxsize += sizeof(__le32); /* Space for length descriptor */
875
876
	/* but wMaxPacketSize might reduce this */
	if (ep->maxpacksize && ep->maxpacksize < maxsize) {
877
		/* whatever fits into a max. size packet */
878
879
880
881
882
883
		unsigned int data_maxsize = maxsize = ep->maxpacksize;

		if (tx_length_quirk)
			/* Need to remove the length descriptor to calc freq */
			data_maxsize -= sizeof(__le32);
		ep->freqmax = (data_maxsize / (frame_bits >> 3))
884
885
886
887
888
889
890
891
				<< (16 - ep->datainterval);
	}

	if (ep->fill_max)
		ep->curpacksize = ep->maxpacksize;
	else
		ep->curpacksize = maxsize;

892
	if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL) {
893
		packs_per_ms = 8 >> ep->datainterval;
894
		max_packs_per_urb = MAX_PACKS_HS;
895
	} else {
896
897
		packs_per_ms = 1;
		max_packs_per_urb = MAX_PACKS;
898
	}
899
	if (sync_ep && !snd_usb_endpoint_implicit_feedback_sink(ep))
900
901
902
903
904
905
906
907
908
909
910
911
912
		max_packs_per_urb = min(max_packs_per_urb,
					1U << sync_ep->syncinterval);
	max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);

	/*
	 * Capture endpoints need to use small URBs because there's no way
	 * to tell in advance where the next period will end, and we don't
	 * want the next URB to complete much after the period ends.
	 *
	 * Playback endpoints with implicit sync much use the same parameters
	 * as their corresponding capture endpoint.
	 */
	if (usb_pipein(ep->pipe) ||
913
914
	    ep->is_implicit_feedback ||
	    snd_usb_endpoint_implicit_feedback_sink(ep)) {
915

916
917
918
919
920
921
922
923
924
925
926
927
928
929
		urb_packs = packs_per_ms;
		/*
		 * Wireless devices can poll at a max rate of once per 4ms.
		 * For dataintervals less than 5, increase the packet count to
		 * allow the host controller to use bursting to fill in the
		 * gaps.
		 */
		if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_WIRELESS) {
			int interval = ep->datainterval;
			while (interval < 5) {
				urb_packs <<= 1;
				++interval;
			}
		}
930
		/* make capture URBs <= 1 ms and smaller than a period */
931
		urb_packs = min(max_packs_per_urb, urb_packs);
932
933
934
		while (urb_packs > 1 && urb_packs * maxsize >= period_bytes)
			urb_packs >>= 1;
		ep->nurbs = MAX_URBS;
935

936
937
938
939
940
941
942
	/*
	 * Playback endpoints without implicit sync are adjusted so that
	 * a period fits as evenly as possible in the smallest number of
	 * URBs.  The total number of URBs is adjusted to the size of the
	 * ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
	 */
	} else {
943
		/* determine how small a packet can be */
944
945
		minsize = (ep->freqn >> (16 - ep->datainterval)) *
				(frame_bits >> 3);
946
947
948
949
950
		/* with sync from device, assume it can be 12% lower */
		if (sync_ep)
			minsize -= minsize >> 3;
		minsize = max(minsize, 1u);

951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
		/* how many packets will contain an entire ALSA period? */
		max_packs_per_period = DIV_ROUND_UP(period_bytes, minsize);

		/* how many URBs will contain a period? */
		urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
				max_packs_per_urb);
		/* how many packets are needed in each URB? */
		urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);

		/* limit the number of frames in a single URB */
		ep->max_urb_frames = DIV_ROUND_UP(frames_per_period,
					urbs_per_period);

		/* try to use enough URBs to contain an entire ALSA buffer */
		max_urbs = min((unsigned) MAX_URBS,
				MAX_QUEUE * packs_per_ms / urb_packs);
		ep->nurbs = min(max_urbs, urbs_per_period * periods_per_buffer);
968
969
970
971
972
973
974
	}

	/* allocate and initialize data urbs */
	for (i = 0; i < ep->nurbs; i++) {
		struct snd_urb_ctx *u = &ep->urb[i];
		u->index = i;
		u->ep = ep;
975
		u->packets = urb_packs;
976
977
978
979
980
981
982
983
984
985
986
987
988
989
		u->buffer_size = maxsize * u->packets;

		if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
			u->packets++; /* for transfer delimiter */
		u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
		if (!u->urb)
			goto out_of_memory;

		u->urb->transfer_buffer =
			usb_alloc_coherent(ep->chip->dev, u->buffer_size,
					   GFP_KERNEL, &u->urb->transfer_dma);
		if (!u->urb->transfer_buffer)
			goto out_of_memory;
		u->urb->pipe = ep->pipe;
990
		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
991
992
993
994
995
996
997
998
999
1000
		u->urb->interval = 1 << ep->datainterval;
		u->urb->context = u;
		u->urb->complete = snd_complete_urb;
		INIT_LIST_HEAD(&u->ready_list);
	}

	return 0;

out_of_memory:
	release_urbs(ep, 0);