endpoint.c 39.9 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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#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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{
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	return  ep->implicit_fb_sync && usb_pipeout(ep->pipe);
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}

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

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	sync_slave = READ_ONCE(ep->sync_slave);
	if (sync_slave)
		snd_usb_handle_sync_urb(sync_slave, 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;

		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;
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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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/*
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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_usb_substream *data_subs;
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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(!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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	data_subs = READ_ONCE(ep->data_subs);
	if (data_subs && data_subs->pcm_substream)
		snd_pcm_stop_xrun(data_subs->pcm_substream);
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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 */
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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,
		      struct audioformat *fp,
		      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;
602

603
604
605
606
607
	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;
608
	}
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
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633
634
635
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640
641
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643
644
645
646
647
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653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673

	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;
			ep->ep_idx = 0;
		}
		usb_audio_dbg(chip, "Open EP 0x%x, iface=%d:%d, idx=%d\n",
			      ep_num, ep->iface, ep->altsetting, ep->ep_idx);

		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 {
		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);
	}

	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)
{
	data_ep->sync_master = sync_ep;
674
675
}

676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
/*
 * 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);
}

694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
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);
	if (!--ep->opened) {
		endpoint_set_interface(chip, ep, false);
		ep->iface = -1;
		ep->altsetting = 0;
		ep->cur_audiofmt = NULL;
		ep->cur_rate = 0;
		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;
}

742
743
744
745
746
747
748
749
750
/*
 *  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 {
751
		alive = bitmap_weight(&ep->active_mask, ep->nurbs);
752
753
754
755
756
757
758
		if (!alive)
			break;

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

	if (alive)
759
760
761
		usb_audio_err(ep->chip,
			"timeout: still %d active urbs on EP #%x\n",
			alive, ep->ep_num);
762
	clear_bit(EP_FLAG_STOPPING, &ep->flags);
763

764
	ep->sync_slave = NULL;
765
	snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
766

767
768
769
	return 0;
}

770
771
772
773
774
775
776
777
778
/* 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);
}

779
780
781
/*
 * unlink active urbs.
 */
782
static int deactivate_urbs(struct snd_usb_endpoint *ep, bool force)
783
784
785
{
	unsigned int i;

786
	if (!force && atomic_read(&ep->chip->shutdown)) /* to be sure... */
787
788
789
790
791
792
793
794
795
796
797
798
		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;
799
				usb_unlink_urb(u);
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
			}
		}
	}

	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 */
815
	snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
816
817

	/* stop urbs */
818
	deactivate_urbs(ep, force);
819
820
821
822
823
	wait_clear_urbs(ep);

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

824
825
	usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
			  ep->syncbuf, ep->sync_dma);
826
827
828
829
830

	ep->syncbuf = NULL;
	ep->nurbs = 0;
}

831
832
833
/*
 * configure a data endpoint
 */
834
static int data_ep_set_params(struct snd_usb_endpoint *ep)
835
{
836
	struct snd_usb_audio *chip = ep->chip;
837
838
839
	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;
840
841
842
	const struct audioformat *fmt = ep->cur_audiofmt;
	int frame_bits = ep->cur_frame_bytes * 8;
	int tx_length_quirk = (chip->tx_length_quirk &&
843
			       usb_pipeout(ep->pipe));
844

845
846
847
848
	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) {
849
850
851
852
853
		/*
		 * 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.
		 */
854
		frame_bits += ep->cur_channels << 3;
855
856
	}

857
858
	ep->datainterval = fmt->datainterval;
	ep->stride = frame_bits >> 3;
859

860
	switch (ep->cur_format) {
861
862
863
864
865
866
867
868
869
870
871
872
873
	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;
	}
874

875
876
	/* assume max. frequency is 50% higher than nominal */
	ep->freqmax = ep->freqn + (ep->freqn >> 1);
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
	/* 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);
894
895
	if (tx_length_quirk)
		maxsize += sizeof(__le32); /* Space for length descriptor */
896
897
	/* but wMaxPacketSize might reduce this */
	if (ep->maxpacksize && ep->maxpacksize < maxsize) {
898
		/* whatever fits into a max. size packet */
899
900
901
902
903
904
		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))
905
906
907
908
909
910
911
912
				<< (16 - ep->datainterval);
	}

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

913
	if (snd_usb_get_speed(chip->dev) != USB_SPEED_FULL) {
914
		packs_per_ms = 8 >> ep->datainterval;
915
		max_packs_per_urb = MAX_PACKS_HS;
916
	} else {
917
918
		packs_per_ms = 1;
		max_packs_per_urb = MAX_PACKS;
919
	}
920
	if (ep->sync_master && !ep->implicit_fb_sync)
921
		max_packs_per_urb = min(max_packs_per_urb,
922
					1U << ep->sync_master->syncinterval);
923
924
925
926
927
928
929
930
931
932
	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.
	 */
933
	if (usb_pipein(ep->pipe) || ep->implicit_fb_sync) {
934

935
936
937
938
939
940
941
		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.
		 */
942
		if (snd_usb_get_speed(chip->dev) == USB_SPEED_WIRELESS) {
943
944
945
946
947
948
			int interval = ep->datainterval;
			while (interval < 5) {
				urb_packs <<= 1;
				++interval;
			}
		}
949
		/* make capture URBs <= 1 ms and smaller than a period */
950
		urb_packs = min(max_packs_per_urb, urb_packs);
951
		while (urb_packs > 1 && urb_packs * maxsize >= ep->cur_period_bytes)
952
953
			urb_packs >>= 1;
		ep->nurbs = MAX_URBS;
954

955
956
957
958
959
960
961
	/*
	 * 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 {
962
		/* determine how small a packet can be */
963
964
		minsize = (ep->freqn >> (16 - ep->datainterval)) *
				(frame_bits >> 3);
965
		/* with sync from device, assume it can be 12% lower */
966
		if (ep->sync_master)
967
968
969
			minsize -= minsize >> 3;
		minsize = max(minsize, 1u);

970
		/* how many packets will contain an entire ALSA period? */
971
		max_packs_per_period = DIV_ROUND_UP(ep->cur_period_bytes, minsize);
972
973
974
975
976
977
978
979

		/* 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 */
980
981
		ep->max_urb_frames = DIV_ROUND_UP(ep->cur_period_frames,
						  urbs_per_period);
982
983
984
985

		/* try to use enough URBs to contain an entire ALSA buffer */
		max_urbs = min((unsigned) MAX_URBS,
				MAX_QUEUE * packs_per_ms / urb_packs);
986
		ep->nurbs = min(max_urbs, urbs_per_period * ep->cur_buffer_periods);
987
988
989
990
991
992
993
	}

	/* 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;
994
		u->packets = urb_packs;
995
996
997
998
999
1000
1001
1002
1003
		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 =
1004
			usb_alloc_coherent(chip->dev, u->buffer_size,
1005
1006
1007
1008
					   GFP_KERNEL, &u->urb->transfer_dma);
		if (!u->urb->transfer_buffer)
			goto out_of_memory;
		u->urb->pipe = ep->pipe;
1009
		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
		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);
	return -ENOMEM;
}

1023
1024
1025
/*
 * configure a sync endpoint
 */
1026
static int sync_ep_set_params(struct snd_usb_endpoint *ep)
1027
{
1028
	struct snd_usb_audio *chip = ep->chip;
1029
1030
	int i;

1031
1032
1033
1034
	usb_audio_dbg(chip, "Setting params for sync EP 0x%x, pipe 0x%x\n",
		      ep->ep_num, ep->pipe);

	ep->syncbuf = usb_alloc_coherent(chip->dev, SYNC_URBS * 4,
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
					 GFP_KERNEL, &ep->sync_dma);
	if (!ep->syncbuf)
		return -ENOMEM;

	for (i = 0; i < SYNC_URBS; i++) {
		struct snd_urb_ctx *u = &ep->urb[i];
		u->index = i;
		u->ep = ep;
		u->packets = 1;
		u->urb = usb_alloc_urb(1, GFP_KERNEL);
		if (!u->urb)
			goto out_of_memory;
		u->urb->transfer_buffer = ep->syncbuf + i * 4;
		u->urb->transfer_dma = ep->sync_dma + i * 4;
		u->urb->transfer_buffer_length = 4;
		u->urb->pipe = ep->pipe;
1051
		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
		u->urb->number_of_packets = 1;
		u->urb->interval = 1 << ep->syncinterval;
		u->urb->context = u;
		u->urb->complete = snd_complete_urb;
	}

	ep->nurbs = SYNC_URBS;

	return 0;

out_of_memory:
	release_urbs(ep, 0);
	return -ENOMEM;
}

1067
/*
1068
 * snd_usb_endpoint_set_params: configure an snd_usb_endpoint
1069
 *
1070
 * Determine the number of URBs to be used on this endpoint.
1071
1072
1073
 * An endpoint must be configured before it can be started.
 * An endpoint that is already running can not be reconfigured.
 */
1074
1075
static int snd_usb_endpoint_set_params(struct snd_usb_audio *chip,
				       struct snd_usb_endpoint *ep)
1076
{
1077
	const struct audioformat *fmt = ep->cur_audiofmt;
1078
1079
1080
1081
1082
1083
1084
	int err;

	/* release old buffers, if any */
	release_urbs(ep, 0);

	ep->datainterval = fmt->datainterval;
	ep->maxpacksize = fmt->maxpacksize;
1085
	ep->fill_max = !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX);
1086

1087
1088
	if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL) {
		ep->freqn = get_usb_full_speed_rate(ep->cur_rate);
1089
		ep->pps = 1000 >> ep->datainterval;
1090
	} else {
1091
		ep->freqn = get_usb_high_speed_rate(ep->cur_rate);
1092
		ep->pps = 8000 >> ep->datainterval;
1093
1094
	}

1095
1096
1097
	ep->sample_rem = ep->cur_rate % ep->pps;
	ep->packsize[0] = ep->cur_rate / ep->pps;
	ep->packsize[1] = (ep->cur_rate + (ep->pps - 1)) / ep->pps;
1098
1099
1100
1101
1102
1103
1104
1105
1106

	/* calculate the frequency in 16.16 format */
	ep->freqm = ep->freqn;
	ep->freqshift = INT_MIN;

	ep->phase = 0;

	switch (ep->type) {
	case  SND_USB_ENDPOINT_TYPE_DATA:
1107
		err = data_ep_set_params(ep);
1108
1109
		break;
	case  SND_USB_ENDPOINT_TYPE_SYNC:
1110
		err = sync_ep_set_params(ep);
1111
1112
1113
1114
1115
		break;
	default:
		err = -EINVAL;
	}

1116
	usb_audio_dbg(chip, "Set up %d URBS, ret=%d\n", ep->nurbs, err);
1117

1118
1119
1120
	if (err < 0)
		return err;

1121
1122
1123
	/* some unit conversions in runtime */
	ep->maxframesize = ep->maxpacksize / ep->cur_frame_bytes;
	ep->curframesize = ep->curpacksize / ep->cur_frame_bytes;
1124
1125

	return 0;
1126
1127
}

1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
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1198
1199
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1201
/*
 * snd_usb_endpoint_configure: Configure the endpoint
 *
 * This function sets up the EP to be fully usable state.
 * It's called either from hw_params or prepare callback.
 * The function checks need_setup flag, and perfoms nothing unless needed,
 * so it's safe to call this multiple times.
 *
 * This returns zero if unchanged, 1 if the configuration has changed,
 * or a negative error code.
 */
int snd_usb_endpoint_configure(struct snd_usb_audio *chip,
			       struct snd_usb_endpoint *ep)
{
	bool iface_first;
	int err = 0;

	mutex_lock(&chip->mutex);
	if (!ep->need_setup)
		goto unlock;

	/* No need to (re-)configure the sync EP belonging to the same altset */
	if (ep->ep_idx) {
		err = snd_usb_endpoint_set_params(chip, ep);
		if (err < 0)
			goto unlock;
		goto done;
	}

	/* Need to deselect altsetting at first */
	endpoint_set_interface(chip, ep, false);

	/* Some UAC1 devices (e.g. Yamaha THR10) need the host interface
	 * to be set up before parameter setups
	 */
	iface_first = ep->cur_audiofmt->protocol == UAC_VERSION_1;
	if (iface_first) {
		err = endpoint_set_interface(chip, ep, true);
		if (err < 0)
			goto unlock;
	}

	err = snd_usb_init_pitch(chip, ep->cur_audiofmt);
	if (err < 0)
		goto unlock;

	err = snd_usb_init_sample_rate(chip, ep->cur_audiofmt, ep->cur_rate);
	if (err < 0)
		goto unlock;

	err = snd_usb_endpoint_set_params(chip, ep);
	if (err < 0)
		goto unlock;

	err = snd_usb_select_mode_quirk(chip, ep->cur_audiofmt);
	if (err < 0)
		goto unlock;

	/* for UAC2/3, enable the interface altset here at last */
	if (!iface_first) {
		err = endpoint_set_interface(chip, ep, true);
		if (err < 0)
			goto unlock;
	}

 done:
	ep->need_setup = false;
	err = 1;

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

1202
1203
1204
/**
 * snd_usb_endpoint_start: start an snd_usb_endpoint
 *
1205
 * @ep: the endpoint to start
1206
1207
 *
 * A call to this function will increment the use count of the endpoint.
1208
 * In case it is not already running, the URBs for this endpoint will be
1209
1210
1211
1212
1213
1214
 * submitted. Otherwise, this function does nothing.
 *
 * Must be balanced to calls of snd_usb_endpoint_stop().
 *
 * Returns an error if the URB submission failed, 0 in all other cases.
 */
1215
int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
1216
1217
1218
1219
{
	int err;
	unsigned int i;

1220
	if (atomic_read(&ep->chip->shutdown))
1221
1222
		return -EBADFD;

1223
1224
1225
	if (ep->sync_master)
		WRITE_ONCE(ep->sync_master->sync_slave, ep);

1226
1227
1228
	usb_audio_dbg(ep->chip, "Starting %s EP 0x%x (count %d)\n",
		      ep_type_name(ep->type), ep->ep_num, ep->use_count);

1229
1230
1231
1232
	/* already running? */
	if (++ep->use_count != 1)
		return 0;

1233
	/* just to be sure */
1234
	deactivate_urbs(ep, false);
1235

1236
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1238
	ep->active_mask = 0;
	ep->unlink_mask = 0;
	ep->phase = 0;
1239
	ep->sample_accum = 0;
1240

1241
1242
	snd_usb_endpoint_start_quirk(ep);

1243
1244
1245
	/*
	 * If this endpoint has a data endpoint as implicit feedback source,
	 * don't start the urbs here. Instead, mark them all as available,
1246
1247
	 * wait for the record urbs to return and queue the playback urbs
	 * from that context.
1248
1249
1250
1251
	 */

	set_bit(EP_FLAG_RUNNING, &ep->flags);

1252
	if (snd_usb_endpoint_implicit_feedback_sink(ep)) {
1253
1254
1255
1256
1257
		for (i = 0; i < ep->nurbs; i++) {
			struct snd_urb_ctx *ctx = ep->urb + i;
			list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
		}

1258
		usb_audio_dbg(ep->chip, "No URB submission due to implicit fb sync\n");
1259
1260
1261
1262
1263
1264
1265
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1267
1268
1269
1270
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		return 0;
	}

	for (i = 0; i < ep->nurbs; i++) {
		struct urb *urb = ep->urb[i].urb;

		if (snd_BUG_ON(!urb))
			goto __error;

		if (usb_pipeout(ep->pipe)) {
			prepare_outbound_urb(ep, urb->context);
		} else {
			prepare_inbound_urb(ep, urb->context);
		}

		err = usb_submit_urb(urb, GFP_ATOMIC);
		if (err < 0) {
1276
1277
1278
			usb_audio_err(ep->chip,
				"cannot submit urb %d, error %d: %s\n",
				i, err, usb_error_string(err));
1279
1280
1281
1282
1283
			goto __error;
		}
		set_bit(i, &ep->active_mask);
	}

1284
1285
	usb_audio_dbg(ep->chip, "%d URBs submitted for EP 0x%x\n",
		      ep->nurbs, ep->ep_num);
1286
1287
1288
	return 0;

__error:
1289
1290
	if (ep->sync_master)
		WRITE_ONCE(ep->sync_master->sync_slave, NULL);
1291
1292
	clear_bit(EP_FLAG_RUNNING, &ep->flags);
	ep->use_count--;
1293
	deactivate_urbs(ep, false);
1294
1295
1296
	return -EPIPE;
}

1297
1298
1299
1300
1301
1302
1303
/**
 * snd_usb_endpoint_stop: stop an snd_usb_endpoint
 *
 * @ep: the endpoint to stop (may be NULL)
 *
 * 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
1304
 * actually be deactivated.
1305
1306
 *
 * Must be balanced to calls of snd_usb_endpoint_start().
1307
1308
1309
 *
 * The caller needs to synchronize the pending stop operation via
 * snd_usb_endpoint_sync_pending_stop().
1310
 */
1311
void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep)
1312
1313
1314
1315
{
	if (!ep)
		return;

1316
1317
1318
	usb_audio_dbg(ep->chip, "Stopping %s EP 0x%x (count %d)\n",
		      ep_type_name(ep->type), ep->ep_num, ep->use_count);

1319
1320
1321
	if (snd_BUG_ON(ep->use_count == 0))
		return;

1322
1323
1324
	if (ep->sync_master)
		WRITE_ONCE(ep->sync_master->sync_slave, NULL);

1325
	if (--ep->use_count == 0) {
1326
		deactivate_urbs(ep, false);
1327
		set_bit(EP_FLAG_STOPPING, &ep->flags);
1328
1329
1330
	}
}

1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
/**
 * snd_usb_endpoint_release: Tear down an snd_usb_endpoint
 *
 * @ep: the endpoint to release
 *
 * This function does not care for the endpoint's use count but will tear
 * down all the streaming URBs immediately.
 */
void snd_usb_endpoint_release(struct snd_usb_endpoint *ep)
{
	release_urbs(ep, 1);
}

1344
1345
/**
 * snd_usb_endpoint_free: Free the resources of an snd_usb_endpoint
1346
 *
1347
 * @ep: the endpoint to free
1348
 *
1349
 * This free all resources of the given ep.
1350
 */
1351
void snd_usb_endpoint_free(struct snd_usb_endpoint *ep)
1352
1353
1354
1355
{
	kfree(ep);
}

1356
/*
1357
1358
1359
1360
1361
1362
1363
1364
 * snd_usb_handle_sync_urb: parse an USB sync packet
 *
 * @ep: the endpoint to handle the packet
 * @sender: the sending endpoint
 * @urb: the received packet
 *
 * This function is called from the context of an endpoint that received
 * the packet and is used to let another endpoint object handle the payload.
1365
 */
1366
1367
1368
static void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
				    struct snd_usb_endpoint *sender,
				    const struct urb *urb)
1369
1370
1371
1372
1373
1374
1375
{
	int shift;
	unsigned int f;
	unsigned long flags;

	snd_BUG_ON(ep == sender);

1376
1377
	/*
	 * In case the endpoint is operating in implicit feedback mode, prepare
1378
1379
1380
	 * 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.
1381
	 */
1382
	if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
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1403