endpoint.c 42.7 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 "clock.h"
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#include "quirks.h"
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enum {
	EP_STATE_STOPPED,
	EP_STATE_RUNNING,
	EP_STATE_STOPPING,
};
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/* interface refcounting */
struct snd_usb_iface_ref {
	unsigned char iface;
	bool need_setup;
	int opened;
	struct list_head list;
};

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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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static inline bool ep_state_running(struct snd_usb_endpoint *ep)
{
	return atomic_read(&ep->state) == EP_STATE_RUNNING;
}

static inline bool ep_state_update(struct snd_usb_endpoint *ep, int old, int new)
{
	return atomic_cmpxchg(&ep->state, old, new) == old;
}

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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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{
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	return  ep->implicit_fb_sync && usb_pipeout(ep->pipe);
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}

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/*
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 * Return the number of samples to be sent in the next packet
 * for streaming based on information derived from sync endpoints
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 *
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 * This won't be used for implicit feedback which takes the packet size
 * returned from the sync source
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 */
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static int 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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/*
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 * Return the number of samples to be sent in the next packet
 * for adaptive and synchronous endpoints
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 */
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static int next_packet_size(struct snd_usb_endpoint *ep)
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{
	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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/*
 * snd_usb_endpoint_next_packet_size: Return the number of samples to be sent
 * in the next packet
 */
int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep,
				      struct snd_urb_ctx *ctx, int idx)
{
	if (ctx->packet_size[idx])
		return ctx->packet_size[idx];
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	else if (ep->sync_source)
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		return slave_next_packet_size(ep);
	else
		return next_packet_size(ep);
}

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static void call_retire_callback(struct snd_usb_endpoint *ep,
				 struct urb *urb)
{
	struct snd_usb_substream *data_subs;

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

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

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static void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
				    struct snd_usb_endpoint *sender,
				    const struct urb *urb);

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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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	struct snd_usb_endpoint *sync_sink;
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	if (unlikely(ep->skip_packets > 0)) {
		ep->skip_packets--;
		return;
	}

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	sync_sink = READ_ONCE(ep->sync_sink);
	if (sync_sink)
		snd_usb_handle_sync_urb(sync_sink, ep, urb);
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	call_retire_callback(ep, urb);
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}

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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;

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		counts = snd_usb_endpoint_next_packet_size(ep, ctx, i);
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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;
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	struct snd_usb_substream *data_subs;
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	urb->dev = ep->chip->dev; /* we need to set this at each time */

	switch (ep->type) {
	case SND_USB_ENDPOINT_TYPE_DATA:
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		data_subs = READ_ONCE(ep->data_subs);
		if (data_subs && ep->prepare_data_urb)
			ep->prepare_data_urb(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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/* notify an error as XRUN to the assigned PCM data substream */
static void notify_xrun(struct snd_usb_endpoint *ep)
{
	struct snd_usb_substream *data_subs;

	data_subs = READ_ONCE(ep->data_subs);
	if (data_subs && data_subs->pcm_substream)
		snd_pcm_stop_xrun(data_subs->pcm_substream);
}

static struct snd_usb_packet_info *
next_packet_fifo_enqueue(struct snd_usb_endpoint *ep)
{
	struct snd_usb_packet_info *p;

	p = ep->next_packet + (ep->next_packet_head + ep->next_packet_queued) %
		ARRAY_SIZE(ep->next_packet);
	ep->next_packet_queued++;
	return p;
}

static struct snd_usb_packet_info *
next_packet_fifo_dequeue(struct snd_usb_endpoint *ep)
{
	struct snd_usb_packet_info *p;

	p = ep->next_packet + ep->next_packet_head;
	ep->next_packet_head++;
	ep->next_packet_head %= ARRAY_SIZE(ep->next_packet);
	ep->next_packet_queued--;
	return p;
}

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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)
{
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	while (ep_state_running(ep)) {
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		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);
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		if (ep->next_packet_queued > 0 &&
		    !list_empty(&ep->ready_playback_urbs)) {
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			/* take URB out of FIFO */
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			ctx = list_first_entry(&ep->ready_playback_urbs,
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					       struct snd_urb_ctx, ready_list);
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			list_del_init(&ctx->ready_list);

			packet = next_packet_fifo_dequeue(ep);
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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);
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		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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			notify_xrun(ep);
			return;
		}

		set_bit(ctx->index, &ep->active_mask);
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	}
}

/*
 * 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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	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(!ep_state_running(ep)))
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		goto exit_clear;

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	if (usb_pipeout(ep->pipe)) {
		retire_outbound_urb(ep, ctx);
		/* can be stopped during retire callback */
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		if (unlikely(!ep_state_running(ep)))
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			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);
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			clear_bit(ctx->index, &ep->active_mask);
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			spin_unlock_irqrestore(&ep->lock, flags);
			queue_pending_output_urbs(ep);
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			return;
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		}

		prepare_outbound_urb(ep, ctx);
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		/* can be stopped during prepare callback */
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		if (unlikely(!ep_state_running(ep)))
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			goto exit_clear;
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	} else {
		retire_inbound_urb(ep, ctx);
		/* can be stopped during retire callback */
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		if (unlikely(!ep_state_running(ep)))
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			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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	notify_xrun(ep);
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exit_clear:
	clear_bit(ctx->index, &ep->active_mask);
}

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/*
 * Find or create a refcount object for the given interface
 *
 * The objects are released altogether in snd_usb_endpoint_free_all()
 */
static struct snd_usb_iface_ref *
iface_ref_find(struct snd_usb_audio *chip, int iface)
{
	struct snd_usb_iface_ref *ip;

	list_for_each_entry(ip, &chip->iface_ref_list, list)
		if (ip->iface == iface)
			return ip;

	ip = kzalloc(sizeof(*ip), GFP_KERNEL);
	if (!ip)
		return NULL;
	ip->iface = iface;
	list_add_tail(&ip->list, &chip->iface_ref_list);
	return ip;
}

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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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 *
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 * New endpoints will be added to chip->ep_list and freed by
 * calling snd_usb_endpoint_free_all().
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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 */
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static void endpoint_set_syncinterval(struct snd_usb_audio *chip,
				      struct snd_usb_endpoint *ep)
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{
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	struct usb_host_interface *alts;
	struct usb_endpoint_descriptor *desc;

	alts = snd_usb_get_host_interface(chip, ep->iface, ep->altsetting);
	if (!alts)
		return;

	desc = get_endpoint(alts, ep->ep_idx);
	if (desc->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
	    desc->bRefresh >= 1 && desc->bRefresh <= 9)
		ep->syncinterval = desc->bRefresh;
	else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL)
		ep->syncinterval = 1;
	else if (desc->bInterval >= 1 && desc->bInterval <= 16)
		ep->syncinterval = desc->bInterval - 1;
	else
		ep->syncinterval = 3;

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

static bool endpoint_compatible(struct snd_usb_endpoint *ep,
				const struct audioformat *fp,
				const struct snd_pcm_hw_params *params)
{
	if (!ep->opened)
		return false;
	if (ep->cur_audiofmt != fp)
		return false;
	if (ep->cur_rate != params_rate(params) ||
	    ep->cur_format != params_format(params) ||
	    ep->cur_period_frames != params_period_size(params) ||
	    ep->cur_buffer_periods != params_periods(params))
		return false;
	return true;
}

/*
 * Check whether the given fp and hw params are compatbile with the current
 * setup of the target EP for implicit feedback sync
 */
bool snd_usb_endpoint_compatible(struct snd_usb_audio *chip,
				 struct snd_usb_endpoint *ep,
				 const struct audioformat *fp,
				 const struct snd_pcm_hw_params *params)
{
	bool ret;

	mutex_lock(&chip->mutex);
	ret = endpoint_compatible(ep, fp, params);
	mutex_unlock(&chip->mutex);
	return ret;
}

/*
 * snd_usb_endpoint_open: Open the endpoint
 *
 * Called from hw_params to assign the endpoint to the substream.
 * It's reference-counted, and only the first opener is allowed to set up
 * arbitrary parameters.  The later opener must be compatible with the
 * former opened parameters.
 * The endpoint needs to be closed via snd_usb_endpoint_close() later.
 *
 * Note that this function doesn't configure the endpoint.  The substream
 * needs to set it up later via snd_usb_endpoint_configure().
 */
struct snd_usb_endpoint *
snd_usb_endpoint_open(struct snd_usb_audio *chip,
677
		      const struct audioformat *fp,
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		      const struct snd_pcm_hw_params *params,
		      bool is_sync_ep)
{
	struct snd_usb_endpoint *ep;
	int ep_num = is_sync_ep ? fp->sync_ep : fp->endpoint;
683

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	mutex_lock(&chip->mutex);
	ep = snd_usb_get_endpoint(chip, ep_num);
	if (!ep) {
		usb_audio_err(chip, "Cannot find EP 0x%x to open\n", ep_num);
		goto unlock;
689
	}
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698

	if (!ep->opened) {
		if (is_sync_ep) {
			ep->iface = fp->sync_iface;
			ep->altsetting = fp->sync_altsetting;
			ep->ep_idx = fp->sync_ep_idx;
		} else {
			ep->iface = fp->iface;
			ep->altsetting = fp->altsetting;
699
			ep->ep_idx = fp->ep_idx;
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		}
		usb_audio_dbg(chip, "Open EP 0x%x, iface=%d:%d, idx=%d\n",
			      ep_num, ep->iface, ep->altsetting, ep->ep_idx);

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		ep->iface_ref = iface_ref_find(chip, ep->iface);
		if (!ep->iface_ref) {
			ep = NULL;
			goto unlock;
		}

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		ep->cur_audiofmt = fp;
		ep->cur_channels = fp->channels;
		ep->cur_rate = params_rate(params);
		ep->cur_format = params_format(params);
		ep->cur_frame_bytes = snd_pcm_format_physical_width(ep->cur_format) *
			ep->cur_channels / 8;
		ep->cur_period_frames = params_period_size(params);
		ep->cur_period_bytes = ep->cur_period_frames * ep->cur_frame_bytes;
		ep->cur_buffer_periods = params_periods(params);

		if (ep->type == SND_USB_ENDPOINT_TYPE_SYNC)
			endpoint_set_syncinterval(chip, ep);

		ep->implicit_fb_sync = fp->implicit_fb;
		ep->need_setup = true;

		usb_audio_dbg(chip, "  channels=%d, rate=%d, format=%s, period_bytes=%d, periods=%d, implicit_fb=%d\n",
			      ep->cur_channels, ep->cur_rate,
			      snd_pcm_format_name(ep->cur_format),
			      ep->cur_period_bytes, ep->cur_buffer_periods,
			      ep->implicit_fb_sync);

	} else {
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		if (WARN_ON(!ep->iface_ref)) {
			ep = NULL;
			goto unlock;
		}

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748
		if (!endpoint_compatible(ep, fp, params)) {
			usb_audio_err(chip, "Incompatible EP setup for 0x%x\n",
				      ep_num);
			ep = NULL;
			goto unlock;
		}

		usb_audio_dbg(chip, "Reopened EP 0x%x (count %d)\n",
			      ep_num, ep->opened);
	}

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	if (!ep->iface_ref->opened++)
		ep->iface_ref->need_setup = true;

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	ep->opened++;

 unlock:
	mutex_unlock(&chip->mutex);
	return ep;
}

/*
 * snd_usb_endpoint_set_sync: Link data and sync endpoints
 *
 * Pass NULL to sync_ep to unlink again
 */
void snd_usb_endpoint_set_sync(struct snd_usb_audio *chip,
			       struct snd_usb_endpoint *data_ep,
			       struct snd_usb_endpoint *sync_ep)
{
768
	data_ep->sync_source = sync_ep;
769
770
}

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/*
 * Set data endpoint callbacks and the assigned data stream
 *
 * Called at PCM trigger and cleanups.
 * Pass NULL to deactivate each callback.
 */
void snd_usb_endpoint_set_callback(struct snd_usb_endpoint *ep,
				   void (*prepare)(struct snd_usb_substream *subs,
						   struct urb *urb),
				   void (*retire)(struct snd_usb_substream *subs,
						  struct urb *urb),
				   struct snd_usb_substream *data_subs)
{
	ep->prepare_data_urb = prepare;
	ep->retire_data_urb = retire;
	WRITE_ONCE(ep->data_subs, data_subs);
}

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static int endpoint_set_interface(struct snd_usb_audio *chip,
				  struct snd_usb_endpoint *ep,
				  bool set)
{
	int altset = set ? ep->altsetting : 0;
	int err;

	usb_audio_dbg(chip, "Setting usb interface %d:%d for EP 0x%x\n",
		      ep->iface, altset, ep->ep_num);
	err = usb_set_interface(chip->dev, ep->iface, altset);
	if (err < 0) {
		usb_audio_err(chip, "%d:%d: usb_set_interface failed (%d)\n",
			      ep->iface, altset, err);
		return err;
	}

	snd_usb_set_interface_quirk(chip);
	return 0;
}

/*
 * snd_usb_endpoint_close: Close the endpoint
 *
 * Unreference the already opened endpoint via snd_usb_endpoint_open().
 */
void snd_usb_endpoint_close(struct snd_usb_audio *chip,
			    struct snd_usb_endpoint *ep)
{
	mutex_lock(&chip->mutex);
	usb_audio_dbg(chip, "Closing EP 0x%x (count %d)\n",
		      ep->ep_num, ep->opened);
820
821

	if (!--ep->iface_ref->opened)
822
		endpoint_set_interface(chip, ep, false);
823
824

	if (!--ep->opened) {
825
		ep->iface = 0;
826
827
828
		ep->altsetting = 0;
		ep->cur_audiofmt = NULL;
		ep->cur_rate = 0;
829
		ep->iface_ref = NULL;
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		usb_audio_dbg(chip, "EP 0x%x closed\n", ep->ep_num);
	}
	mutex_unlock(&chip->mutex);
}

/* Prepare for suspening EP, called from the main suspend handler */
void snd_usb_endpoint_suspend(struct snd_usb_endpoint *ep)
{
	ep->need_setup = true;
839
840
	if (ep->iface_ref)
		ep->iface_ref->need_setup = true;
841
842
}

843
844
845
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848
849
850
/*
 *  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;

851
	if (atomic_read(&ep->state) != EP_STATE_STOPPING)
852
853
		return 0;

854
	do {
855
		alive = bitmap_weight(&ep->active_mask, ep->nurbs);
856
857
858
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861
862
		if (!alive)
			break;

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

	if (alive)
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865
		usb_audio_err(ep->chip,
			"timeout: still %d active urbs on EP #%x\n",
			alive, ep->ep_num);
866

867
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870
	if (ep_state_update(ep, EP_STATE_STOPPING, EP_STATE_STOPPED)) {
		ep->sync_sink = NULL;
		snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
	}
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	return 0;
}

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879
/* 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)
{
880
	if (ep)
881
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883
		wait_clear_urbs(ep);
}

884
/*
885
 * Stop active urbs
886
 *
887
 * This function moves the EP to STOPPING state if it's being RUNNING.
888
 */
889
static int stop_urbs(struct snd_usb_endpoint *ep, bool force)
890
891
892
{
	unsigned int i;

893
	if (!force && atomic_read(&ep->running))
894
895
		return -EBUSY;

896
	if (!ep_state_update(ep, EP_STATE_RUNNING, EP_STATE_STOPPING))
897
		return 0;
898
899

	INIT_LIST_HEAD(&ep->ready_playback_urbs);
900
901
	ep->next_packet_head = 0;
	ep->next_packet_queued = 0;
902
903
904
905
906

	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;
907
				usb_unlink_urb(u);
908
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			}
		}
	}

	return 0;
}

/*
 * release an endpoint's urbs
 */
918
static int release_urbs(struct snd_usb_endpoint *ep, bool force)
919
{
920
	int i, err;
921
922

	/* route incoming urbs to nirvana */
923
	snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
924

925
926
927
928
929
930
	/* stop and unlink urbs */
	err = stop_urbs(ep, force);
	if (err)
		return err;

	wait_clear_urbs(ep);
931
932
933
934

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

935
936
	usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
			  ep->syncbuf, ep->sync_dma);
937
938
939

	ep->syncbuf = NULL;
	ep->nurbs = 0;
940
	return 0;
941
942
}

943
944
945
/*
 * configure a data endpoint
 */
946
static int data_ep_set_params(struct snd_usb_endpoint *ep)
947
{
948
	struct snd_usb_audio *chip = ep->chip;
949
950
951
	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;
952
953
954
	const struct audioformat *fmt = ep->cur_audiofmt;
	int frame_bits = ep->cur_frame_bytes * 8;
	int tx_length_quirk = (chip->tx_length_quirk &&
955
			       usb_pipeout(ep->pipe));
956

957
958
959
960
	usb_audio_dbg(chip, "Setting params for data EP 0x%x, pipe 0x%x\n",
		      ep->ep_num, ep->pipe);

	if (ep->cur_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
961
962
963
964
965
		/*
		 * 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.
		 */
966
		frame_bits += ep->cur_channels << 3;
967
968
	}

969
970
	ep->datainterval = fmt->datainterval;
	ep->stride = frame_bits >> 3;
971

972
	switch (ep->cur_format) {
973
974
975
976
977
978
979
980
981
982
983
984
985
	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;
	}
986

987
988
	/* assume max. frequency is 50% higher than nominal */
	ep->freqmax = ep->freqn + (ep->freqn >> 1);
989
990
991
992
993
994
995
996
997
998
999
1000
	/* 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
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