1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 */
   4
   5#include <linux/gfp.h>
   6#include <linux/init.h>
   7#include <linux/ratelimit.h>
   8#include <linux/usb.h>
   9#include <linux/usb/audio.h>
  10#include <linux/slab.h>
  11
  12#include <sound/core.h>
  13#include <sound/pcm.h>
  14#include <sound/pcm_params.h>
  15
  16#include "usbaudio.h"
  17#include "helper.h"
  18#include "card.h"
  19#include "endpoint.h"
  20#include "pcm.h"
  21#include "quirks.h"
  22
  23#define EP_FLAG_RUNNING		1
  24#define EP_FLAG_STOPPING	2
  25
  26/*
  27 * snd_usb_endpoint is a model that abstracts everything related to an
  28 * USB endpoint and its streaming.
  29 *
  30 * There are functions to activate and deactivate the streaming URBs and
  31 * optional callbacks to let the pcm logic handle the actual content of the
  32 * packets for playback and record. Thus, the bus streaming and the audio
  33 * handlers are fully decoupled.
  34 *
  35 * There are two different types of endpoints in audio applications.
  36 *
  37 * SND_USB_ENDPOINT_TYPE_DATA handles full audio data payload for both
  38 * inbound and outbound traffic.
  39 *
  40 * SND_USB_ENDPOINT_TYPE_SYNC endpoints are for inbound traffic only and
  41 * expect the payload to carry Q10.14 / Q16.16 formatted sync information
  42 * (3 or 4 bytes).
  43 *
  44 * Each endpoint has to be configured prior to being used by calling
  45 * snd_usb_endpoint_set_params().
  46 *
  47 * The model incorporates a reference counting, so that multiple users
  48 * can call snd_usb_endpoint_start() and snd_usb_endpoint_stop(), and
  49 * only the first user will effectively start the URBs, and only the last
  50 * one to stop it will tear the URBs down again.
  51 */
  52
  53/*
  54 * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
  55 * this will overflow at approx 524 kHz
  56 */
  57static inline unsigned get_usb_full_speed_rate(unsigned int rate)
  58{
  59	return ((rate << 13) + 62) / 125;
  60}
  61
  62/*
  63 * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
  64 * this will overflow at approx 4 MHz
  65 */
  66static inline unsigned get_usb_high_speed_rate(unsigned int rate)
  67{
  68	return ((rate << 10) + 62) / 125;
  69}
  70
  71/*
  72 * release a urb data
  73 */
  74static void release_urb_ctx(struct snd_urb_ctx *u)
  75{
  76	if (u->buffer_size)
  77		usb_free_coherent(u->ep->chip->dev, u->buffer_size,
  78				  u->urb->transfer_buffer,
  79				  u->urb->transfer_dma);
  80	usb_free_urb(u->urb);
  81	u->urb = NULL;
  82}
  83
  84static const char *usb_error_string(int err)
  85{
  86	switch (err) {
  87	case -ENODEV:
  88		return "no device";
  89	case -ENOENT:
  90		return "endpoint not enabled";
  91	case -EPIPE:
  92		return "endpoint stalled";
  93	case -ENOSPC:
  94		return "not enough bandwidth";
  95	case -ESHUTDOWN:
  96		return "device disabled";
  97	case -EHOSTUNREACH:
  98		return "device suspended";
  99	case -EINVAL:
 100	case -EAGAIN:
 101	case -EFBIG:
 102	case -EMSGSIZE:
 103		return "internal error";
 104	default:
 105		return "unknown error";
 106	}
 107}
 108
 109/**
 110 * snd_usb_endpoint_implicit_feedback_sink: Report endpoint usage type
 111 *
 112 * @ep: The snd_usb_endpoint
 113 *
 114 * Determine whether an endpoint is driven by an implicit feedback
 115 * data endpoint source.
 116 */
 117int snd_usb_endpoint_implicit_feedback_sink(struct snd_usb_endpoint *ep)
 118{
 119	return  ep->sync_master &&
 120		ep->sync_master->type == SND_USB_ENDPOINT_TYPE_DATA &&
 121		ep->type == SND_USB_ENDPOINT_TYPE_DATA &&
 122		usb_pipeout(ep->pipe);
 123}
 124
 125/*
 126 * For streaming based on information derived from sync endpoints,
 127 * prepare_outbound_urb_sizes() will call slave_next_packet_size() to
 128 * determine the number of samples to be sent in the next packet.
 129 *
 130 * For implicit feedback, slave_next_packet_size() is unused.
 131 */
 132int snd_usb_endpoint_slave_next_packet_size(struct snd_usb_endpoint *ep)
 133{
 134	unsigned long flags;
 135	int ret;
 136
 137	if (ep->fill_max)
 138		return ep->maxframesize;
 139
 140	spin_lock_irqsave(&ep->lock, flags);
 141	ep->phase = (ep->phase & 0xffff)
 142		+ (ep->freqm << ep->datainterval);
 143	ret = min(ep->phase >> 16, ep->maxframesize);
 144	spin_unlock_irqrestore(&ep->lock, flags);
 145
 146	return ret;
 147}
 148
 149/*
 150 * For adaptive and synchronous endpoints, prepare_outbound_urb_sizes()
 151 * will call next_packet_size() to determine the number of samples to be
 152 * sent in the next packet.
 153 */
 154int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep)
 155{
 156	int ret;
 157
 158	if (ep->fill_max)
 159		return ep->maxframesize;
 160
 161	ep->sample_accum += ep->sample_rem;
 162	if (ep->sample_accum >= ep->pps) {
 163		ep->sample_accum -= ep->pps;
 164		ret = ep->packsize[1];
 165	} else {
 166		ret = ep->packsize[0];
 167	}
 168
 169	return ret;
 170}
 171
 172static void retire_outbound_urb(struct snd_usb_endpoint *ep,
 173				struct snd_urb_ctx *urb_ctx)
 174{
 175	if (ep->retire_data_urb)
 176		ep->retire_data_urb(ep->data_subs, urb_ctx->urb);
 177}
 178
 179static void retire_inbound_urb(struct snd_usb_endpoint *ep,
 180			       struct snd_urb_ctx *urb_ctx)
 181{
 182	struct urb *urb = urb_ctx->urb;
 183
 184	if (unlikely(ep->skip_packets > 0)) {
 185		ep->skip_packets--;
 186		return;
 187	}
 188
 189	if (ep->sync_slave)
 190		snd_usb_handle_sync_urb(ep->sync_slave, ep, urb);
 191
 192	if (ep->retire_data_urb)
 193		ep->retire_data_urb(ep->data_subs, urb);
 194}
 195
 196static void prepare_silent_urb(struct snd_usb_endpoint *ep,
 197			       struct snd_urb_ctx *ctx)
 198{
 199	struct urb *urb = ctx->urb;
 200	unsigned int offs = 0;
 201	unsigned int extra = 0;
 202	__le32 packet_length;
 203	int i;
 204
 205	/* For tx_length_quirk, put packet length at start of packet */
 206	if (ep->chip->tx_length_quirk)
 207		extra = sizeof(packet_length);
 208
 209	for (i = 0; i < ctx->packets; ++i) {
 210		unsigned int offset;
 211		unsigned int length;
 212		int counts;
 213
 214		if (ctx->packet_size[i])
 215			counts = ctx->packet_size[i];
 216		else if (ep->sync_master)
 217			counts = snd_usb_endpoint_slave_next_packet_size(ep);
 218		else
 219			counts = snd_usb_endpoint_next_packet_size(ep);
 220
 221		length = counts * ep->stride; /* number of silent bytes */
 222		offset = offs * ep->stride + extra * i;
 223		urb->iso_frame_desc[i].offset = offset;
 224		urb->iso_frame_desc[i].length = length + extra;
 225		if (extra) {
 226			packet_length = cpu_to_le32(length);
 227			memcpy(urb->transfer_buffer + offset,
 228			       &packet_length, sizeof(packet_length));
 229		}
 230		memset(urb->transfer_buffer + offset + extra,
 231		       ep->silence_value, length);
 232		offs += counts;
 233	}
 234
 235	urb->number_of_packets = ctx->packets;
 236	urb->transfer_buffer_length = offs * ep->stride + ctx->packets * extra;
 237}
 238
 239/*
 240 * Prepare a PLAYBACK urb for submission to the bus.
 241 */
 242static void prepare_outbound_urb(struct snd_usb_endpoint *ep,
 243				 struct snd_urb_ctx *ctx)
 244{
 245	struct urb *urb = ctx->urb;
 246	unsigned char *cp = urb->transfer_buffer;
 247
 248	urb->dev = ep->chip->dev; /* we need to set this at each time */
 249
 250	switch (ep->type) {
 251	case SND_USB_ENDPOINT_TYPE_DATA:
 252		if (ep->prepare_data_urb) {
 253			ep->prepare_data_urb(ep->data_subs, urb);
 254		} else {
 255			/* no data provider, so send silence */
 256			prepare_silent_urb(ep, ctx);
 257		}
 258		break;
 259
 260	case SND_USB_ENDPOINT_TYPE_SYNC:
 261		if (snd_usb_get_speed(ep->chip->dev) >= USB_SPEED_HIGH) {
 262			/*
 263			 * fill the length and offset of each urb descriptor.
 264			 * the fixed 12.13 frequency is passed as 16.16 through the pipe.
 265			 */
 266			urb->iso_frame_desc[0].length = 4;
 267			urb->iso_frame_desc[0].offset = 0;
 268			cp[0] = ep->freqn;
 269			cp[1] = ep->freqn >> 8;
 270			cp[2] = ep->freqn >> 16;
 271			cp[3] = ep->freqn >> 24;
 272		} else {
 273			/*
 274			 * fill the length and offset of each urb descriptor.
 275			 * the fixed 10.14 frequency is passed through the pipe.
 276			 */
 277			urb->iso_frame_desc[0].length = 3;
 278			urb->iso_frame_desc[0].offset = 0;
 279			cp[0] = ep->freqn >> 2;
 280			cp[1] = ep->freqn >> 10;
 281			cp[2] = ep->freqn >> 18;
 282		}
 283
 284		break;
 285	}
 286}
 287
 288/*
 289 * Prepare a CAPTURE or SYNC urb for submission to the bus.
 290 */
 291static inline void prepare_inbound_urb(struct snd_usb_endpoint *ep,
 292				       struct snd_urb_ctx *urb_ctx)
 293{
 294	int i, offs;
 295	struct urb *urb = urb_ctx->urb;
 296
 297	urb->dev = ep->chip->dev; /* we need to set this at each time */
 298
 299	switch (ep->type) {
 300	case SND_USB_ENDPOINT_TYPE_DATA:
 301		offs = 0;
 302		for (i = 0; i < urb_ctx->packets; i++) {
 303			urb->iso_frame_desc[i].offset = offs;
 304			urb->iso_frame_desc[i].length = ep->curpacksize;
 305			offs += ep->curpacksize;
 306		}
 307
 308		urb->transfer_buffer_length = offs;
 309		urb->number_of_packets = urb_ctx->packets;
 310		break;
 311
 312	case SND_USB_ENDPOINT_TYPE_SYNC:
 313		urb->iso_frame_desc[0].length = min(4u, ep->syncmaxsize);
 314		urb->iso_frame_desc[0].offset = 0;
 315		break;
 316	}
 317}
 318
 319/*
 320 * Send output urbs that have been prepared previously. URBs are dequeued
 321 * from ep->ready_playback_urbs and in case there there aren't any available
 322 * or there are no packets that have been prepared, this function does
 323 * nothing.
 324 *
 325 * The reason why the functionality of sending and preparing URBs is separated
 326 * is that host controllers don't guarantee the order in which they return
 327 * inbound and outbound packets to their submitters.
 328 *
 329 * This function is only used for implicit feedback endpoints. For endpoints
 330 * driven by dedicated sync endpoints, URBs are immediately re-submitted
 331 * from their completion handler.
 332 */
 333static void queue_pending_output_urbs(struct snd_usb_endpoint *ep)
 334{
 335	while (test_bit(EP_FLAG_RUNNING, &ep->flags)) {
 336
 337		unsigned long flags;
 338		struct snd_usb_packet_info *packet;
 339		struct snd_urb_ctx *ctx = NULL;
 340		int err, i;
 341
 342		spin_lock_irqsave(&ep->lock, flags);
 343		if (ep->next_packet_read_pos != ep->next_packet_write_pos) {
 344			packet = ep->next_packet + ep->next_packet_read_pos;
 345			ep->next_packet_read_pos++;
 346			ep->next_packet_read_pos %= MAX_URBS;
 347
 348			/* take URB out of FIFO */
 349			if (!list_empty(&ep->ready_playback_urbs)) {
 350				ctx = list_first_entry(&ep->ready_playback_urbs,
 351					       struct snd_urb_ctx, ready_list);
 352				list_del_init(&ctx->ready_list);
 353			}
 354		}
 355		spin_unlock_irqrestore(&ep->lock, flags);
 356
 357		if (ctx == NULL)
 358			return;
 359
 
 
 360		/* copy over the length information */
 361		for (i = 0; i < packet->packets; i++)
 362			ctx->packet_size[i] = packet->packet_size[i];
 363
 364		/* call the data handler to fill in playback data */
 365		prepare_outbound_urb(ep, ctx);
 366
 367		err = usb_submit_urb(ctx->urb, GFP_ATOMIC);
 368		if (err < 0)
 369			usb_audio_err(ep->chip,
 370				"Unable to submit urb #%d: %d (urb %p)\n",
 371				ctx->index, err, ctx->urb);
 372		else
 373			set_bit(ctx->index, &ep->active_mask);
 374	}
 375}
 376
 377/*
 378 * complete callback for urbs
 379 */
 380static void snd_complete_urb(struct urb *urb)
 381{
 382	struct snd_urb_ctx *ctx = urb->context;
 383	struct snd_usb_endpoint *ep = ctx->ep;
 384	struct snd_pcm_substream *substream;
 385	unsigned long flags;
 386	int err;
 387
 388	if (unlikely(urb->status == -ENOENT ||		/* unlinked */
 389		     urb->status == -ENODEV ||		/* device removed */
 390		     urb->status == -ECONNRESET ||	/* unlinked */
 391		     urb->status == -ESHUTDOWN))	/* device disabled */
 392		goto exit_clear;
 393	/* device disconnected */
 394	if (unlikely(atomic_read(&ep->chip->shutdown)))
 395		goto exit_clear;
 396
 397	if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
 398		goto exit_clear;
 399
 400	if (usb_pipeout(ep->pipe)) {
 401		retire_outbound_urb(ep, ctx);
 402		/* can be stopped during retire callback */
 403		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
 404			goto exit_clear;
 405
 406		if (snd_usb_endpoint_implicit_feedback_sink(ep)) {
 407			spin_lock_irqsave(&ep->lock, flags);
 408			list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
 409			spin_unlock_irqrestore(&ep->lock, flags);
 410			queue_pending_output_urbs(ep);
 411
 412			goto exit_clear;
 413		}
 414
 415		prepare_outbound_urb(ep, ctx);
 416		/* can be stopped during prepare callback */
 417		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
 418			goto exit_clear;
 419	} else {
 420		retire_inbound_urb(ep, ctx);
 421		/* can be stopped during retire callback */
 422		if (unlikely(!test_bit(EP_FLAG_RUNNING, &ep->flags)))
 423			goto exit_clear;
 424
 425		prepare_inbound_urb(ep, ctx);
 426	}
 427
 428	err = usb_submit_urb(urb, GFP_ATOMIC);
 429	if (err == 0)
 430		return;
 431
 432	usb_audio_err(ep->chip, "cannot submit urb (err = %d)\n", err);
 433	if (ep->data_subs && ep->data_subs->pcm_substream) {
 434		substream = ep->data_subs->pcm_substream;
 435		snd_pcm_stop_xrun(substream);
 436	}
 437
 438exit_clear:
 439	clear_bit(ctx->index, &ep->active_mask);
 440}
 441
 442/**
 443 * snd_usb_add_endpoint: Add an endpoint to an USB audio chip
 444 *
 445 * @chip: The chip
 446 * @alts: The USB host interface
 447 * @ep_num: The number of the endpoint to use
 448 * @direction: SNDRV_PCM_STREAM_PLAYBACK or SNDRV_PCM_STREAM_CAPTURE
 449 * @type: SND_USB_ENDPOINT_TYPE_DATA or SND_USB_ENDPOINT_TYPE_SYNC
 450 *
 451 * If the requested endpoint has not been added to the given chip before,
 452 * a new instance is created. Otherwise, a pointer to the previoulsy
 453 * created instance is returned. In case of any error, NULL is returned.
 454 *
 455 * New endpoints will be added to chip->ep_list and must be freed by
 456 * calling snd_usb_endpoint_free().
 457 *
 458 * For SND_USB_ENDPOINT_TYPE_SYNC, the caller needs to guarantee that
 459 * bNumEndpoints > 1 beforehand.
 460 */
 461struct snd_usb_endpoint *snd_usb_add_endpoint(struct snd_usb_audio *chip,
 462					      struct usb_host_interface *alts,
 463					      int ep_num, int direction, int type)
 464{
 465	struct snd_usb_endpoint *ep;
 466	int is_playback = direction == SNDRV_PCM_STREAM_PLAYBACK;
 467
 468	if (WARN_ON(!alts))
 469		return NULL;
 470
 471	mutex_lock(&chip->mutex);
 472
 473	list_for_each_entry(ep, &chip->ep_list, list) {
 474		if (ep->ep_num == ep_num &&
 475		    ep->iface == alts->desc.bInterfaceNumber &&
 476		    ep->altsetting == alts->desc.bAlternateSetting) {
 477			usb_audio_dbg(ep->chip,
 478				      "Re-using EP %x in iface %d,%d @%p\n",
 479					ep_num, ep->iface, ep->altsetting, ep);
 480			goto __exit_unlock;
 481		}
 482	}
 483
 484	usb_audio_dbg(chip, "Creating new %s %s endpoint #%x\n",
 485		    is_playback ? "playback" : "capture",
 486		    type == SND_USB_ENDPOINT_TYPE_DATA ? "data" : "sync",
 487		    ep_num);
 488
 489	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
 490	if (!ep)
 491		goto __exit_unlock;
 492
 493	ep->chip = chip;
 494	spin_lock_init(&ep->lock);
 495	ep->type = type;
 496	ep->ep_num = ep_num;
 497	ep->iface = alts->desc.bInterfaceNumber;
 498	ep->altsetting = alts->desc.bAlternateSetting;
 499	INIT_LIST_HEAD(&ep->ready_playback_urbs);
 500	ep_num &= USB_ENDPOINT_NUMBER_MASK;
 501
 502	if (is_playback)
 503		ep->pipe = usb_sndisocpipe(chip->dev, ep_num);
 504	else
 505		ep->pipe = usb_rcvisocpipe(chip->dev, ep_num);
 506
 507	if (type == SND_USB_ENDPOINT_TYPE_SYNC) {
 508		if (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
 509		    get_endpoint(alts, 1)->bRefresh >= 1 &&
 510		    get_endpoint(alts, 1)->bRefresh <= 9)
 511			ep->syncinterval = get_endpoint(alts, 1)->bRefresh;
 512		else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL)
 513			ep->syncinterval = 1;
 514		else if (get_endpoint(alts, 1)->bInterval >= 1 &&
 515			 get_endpoint(alts, 1)->bInterval <= 16)
 516			ep->syncinterval = get_endpoint(alts, 1)->bInterval - 1;
 517		else
 518			ep->syncinterval = 3;
 519
 520		ep->syncmaxsize = le16_to_cpu(get_endpoint(alts, 1)->wMaxPacketSize);
 521	}
 522
 523	list_add_tail(&ep->list, &chip->ep_list);
 524
 525	ep->is_implicit_feedback = 0;
 526
 527__exit_unlock:
 528	mutex_unlock(&chip->mutex);
 529
 530	return ep;
 531}
 532
 533/*
 534 *  wait until all urbs are processed.
 535 */
 536static int wait_clear_urbs(struct snd_usb_endpoint *ep)
 537{
 538	unsigned long end_time = jiffies + msecs_to_jiffies(1000);
 539	int alive;
 540
 541	do {
 542		alive = bitmap_weight(&ep->active_mask, ep->nurbs);
 543		if (!alive)
 544			break;
 545
 546		schedule_timeout_uninterruptible(1);
 547	} while (time_before(jiffies, end_time));
 548
 549	if (alive)
 550		usb_audio_err(ep->chip,
 551			"timeout: still %d active urbs on EP #%x\n",
 552			alive, ep->ep_num);
 553	clear_bit(EP_FLAG_STOPPING, &ep->flags);
 554
 555	ep->data_subs = NULL;
 556	ep->sync_slave = NULL;
 557	ep->retire_data_urb = NULL;
 558	ep->prepare_data_urb = NULL;
 559
 560	return 0;
 561}
 562
 563/* sync the pending stop operation;
 564 * this function itself doesn't trigger the stop operation
 565 */
 566void snd_usb_endpoint_sync_pending_stop(struct snd_usb_endpoint *ep)
 567{
 568	if (ep && test_bit(EP_FLAG_STOPPING, &ep->flags))
 569		wait_clear_urbs(ep);
 570}
 571
 572/*
 573 * unlink active urbs.
 574 */
 575static int deactivate_urbs(struct snd_usb_endpoint *ep, bool force)
 576{
 577	unsigned int i;
 578
 579	if (!force && atomic_read(&ep->chip->shutdown)) /* to be sure... */
 580		return -EBADFD;
 581
 582	clear_bit(EP_FLAG_RUNNING, &ep->flags);
 583
 584	INIT_LIST_HEAD(&ep->ready_playback_urbs);
 585	ep->next_packet_read_pos = 0;
 586	ep->next_packet_write_pos = 0;
 587
 588	for (i = 0; i < ep->nurbs; i++) {
 589		if (test_bit(i, &ep->active_mask)) {
 590			if (!test_and_set_bit(i, &ep->unlink_mask)) {
 591				struct urb *u = ep->urb[i].urb;
 592				usb_unlink_urb(u);
 593			}
 594		}
 595	}
 596
 597	return 0;
 598}
 599
 600/*
 601 * release an endpoint's urbs
 602 */
 603static void release_urbs(struct snd_usb_endpoint *ep, int force)
 604{
 605	int i;
 606
 607	/* route incoming urbs to nirvana */
 608	ep->retire_data_urb = NULL;
 609	ep->prepare_data_urb = NULL;
 610
 611	/* stop urbs */
 612	deactivate_urbs(ep, force);
 613	wait_clear_urbs(ep);
 614
 615	for (i = 0; i < ep->nurbs; i++)
 616		release_urb_ctx(&ep->urb[i]);
 617
 618	usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
 619			  ep->syncbuf, ep->sync_dma);
 
 620
 621	ep->syncbuf = NULL;
 622	ep->nurbs = 0;
 623}
 624
 625/*
 626 * Check data endpoint for format differences
 627 */
 628static bool check_ep_params(struct snd_usb_endpoint *ep,
 629			      snd_pcm_format_t pcm_format,
 630			      unsigned int channels,
 631			      unsigned int period_bytes,
 632			      unsigned int frames_per_period,
 633			      unsigned int periods_per_buffer,
 634			      struct audioformat *fmt,
 635			      struct snd_usb_endpoint *sync_ep)
 636{
 637	unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
 638	unsigned int max_packs_per_period, urbs_per_period, urb_packs;
 639	unsigned int max_urbs;
 640	int frame_bits = snd_pcm_format_physical_width(pcm_format) * channels;
 641	int tx_length_quirk = (ep->chip->tx_length_quirk &&
 642			       usb_pipeout(ep->pipe));
 643	bool ret = 1;
 644
 645	if (pcm_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
 646		/*
 647		 * When operating in DSD DOP mode, the size of a sample frame
 648		 * in hardware differs from the actual physical format width
 649		 * because we need to make room for the DOP markers.
 650		 */
 651		frame_bits += channels << 3;
 652	}
 653
 654	ret = ret && (ep->datainterval == fmt->datainterval);
 655	ret = ret && (ep->stride == frame_bits >> 3);
 656
 657	switch (pcm_format) {
 658	case SNDRV_PCM_FORMAT_U8:
 659		ret = ret && (ep->silence_value == 0x80);
 660		break;
 661	case SNDRV_PCM_FORMAT_DSD_U8:
 662	case SNDRV_PCM_FORMAT_DSD_U16_LE:
 663	case SNDRV_PCM_FORMAT_DSD_U32_LE:
 664	case SNDRV_PCM_FORMAT_DSD_U16_BE:
 665	case SNDRV_PCM_FORMAT_DSD_U32_BE:
 666		ret = ret && (ep->silence_value == 0x69);
 667		break;
 668	default:
 669		ret = ret && (ep->silence_value == 0);
 670	}
 671
 672	/* assume max. frequency is 50% higher than nominal */
 673	ret = ret && (ep->freqmax == ep->freqn + (ep->freqn >> 1));
 674	/* Round up freqmax to nearest integer in order to calculate maximum
 675	 * packet size, which must represent a whole number of frames.
 676	 * This is accomplished by adding 0x0.ffff before converting the
 677	 * Q16.16 format into integer.
 678	 * In order to accurately calculate the maximum packet size when
 679	 * the data interval is more than 1 (i.e. ep->datainterval > 0),
 680	 * multiply by the data interval prior to rounding. For instance,
 681	 * a freqmax of 41 kHz will result in a max packet size of 6 (5.125)
 682	 * frames with a data interval of 1, but 11 (10.25) frames with a
 683	 * data interval of 2.
 684	 * (ep->freqmax << ep->datainterval overflows at 8.192 MHz for the
 685	 * maximum datainterval value of 3, at USB full speed, higher for
 686	 * USB high speed, noting that ep->freqmax is in units of
 687	 * frames per packet in Q16.16 format.)
 688	 */
 689	maxsize = (((ep->freqmax << ep->datainterval) + 0xffff) >> 16) *
 690			 (frame_bits >> 3);
 691	if (tx_length_quirk)
 692		maxsize += sizeof(__le32); /* Space for length descriptor */
 693	/* but wMaxPacketSize might reduce this */
 694	if (ep->maxpacksize && ep->maxpacksize < maxsize) {
 695		/* whatever fits into a max. size packet */
 696		unsigned int data_maxsize = maxsize = ep->maxpacksize;
 697
 698		if (tx_length_quirk)
 699			/* Need to remove the length descriptor to calc freq */
 700			data_maxsize -= sizeof(__le32);
 701		ret = ret && (ep->freqmax == (data_maxsize / (frame_bits >> 3))
 702				<< (16 - ep->datainterval));
 703	}
 704
 705	if (ep->fill_max)
 706		ret = ret && (ep->curpacksize == ep->maxpacksize);
 707	else
 708		ret = ret && (ep->curpacksize == maxsize);
 709
 710	if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL) {
 711		packs_per_ms = 8 >> ep->datainterval;
 712		max_packs_per_urb = MAX_PACKS_HS;
 713	} else {
 714		packs_per_ms = 1;
 715		max_packs_per_urb = MAX_PACKS;
 716	}
 717	if (sync_ep && !snd_usb_endpoint_implicit_feedback_sink(ep))
 718		max_packs_per_urb = min(max_packs_per_urb,
 719					1U << sync_ep->syncinterval);
 720	max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);
 721
 722	/*
 723	 * Capture endpoints need to use small URBs because there's no way
 724	 * to tell in advance where the next period will end, and we don't
 725	 * want the next URB to complete much after the period ends.
 726	 *
 727	 * Playback endpoints with implicit sync much use the same parameters
 728	 * as their corresponding capture endpoint.
 729	 */
 730	if (usb_pipein(ep->pipe) ||
 731			snd_usb_endpoint_implicit_feedback_sink(ep)) {
 732
 733		urb_packs = packs_per_ms;
 734		/*
 735		 * Wireless devices can poll at a max rate of once per 4ms.
 736		 * For dataintervals less than 5, increase the packet count to
 737		 * allow the host controller to use bursting to fill in the
 738		 * gaps.
 739		 */
 740		if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_WIRELESS) {
 741			int interval = ep->datainterval;
 742
 743			while (interval < 5) {
 744				urb_packs <<= 1;
 745				++interval;
 746			}
 747		}
 748		/* make capture URBs <= 1 ms and smaller than a period */
 749		urb_packs = min(max_packs_per_urb, urb_packs);
 750		while (urb_packs > 1 && urb_packs * maxsize >= period_bytes)
 751			urb_packs >>= 1;
 752		ret = ret && (ep->nurbs == MAX_URBS);
 753
 754	/*
 755	 * Playback endpoints without implicit sync are adjusted so that
 756	 * a period fits as evenly as possible in the smallest number of
 757	 * URBs.  The total number of URBs is adjusted to the size of the
 758	 * ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
 759	 */
 760	} else {
 761		/* determine how small a packet can be */
 762		minsize = (ep->freqn >> (16 - ep->datainterval)) *
 763				(frame_bits >> 3);
 764		/* with sync from device, assume it can be 12% lower */
 765		if (sync_ep)
 766			minsize -= minsize >> 3;
 767		minsize = max(minsize, 1u);
 768
 769		/* how many packets will contain an entire ALSA period? */
 770		max_packs_per_period = DIV_ROUND_UP(period_bytes, minsize);
 771
 772		/* how many URBs will contain a period? */
 773		urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
 774				max_packs_per_urb);
 775		/* how many packets are needed in each URB? */
 776		urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);
 777
 778		/* limit the number of frames in a single URB */
 779		ret = ret && (ep->max_urb_frames ==
 780			DIV_ROUND_UP(frames_per_period, urbs_per_period));
 781
 782		/* try to use enough URBs to contain an entire ALSA buffer */
 783		max_urbs = min((unsigned) MAX_URBS,
 784				MAX_QUEUE * packs_per_ms / urb_packs);
 785		ret = ret && (ep->nurbs == min(max_urbs,
 786				urbs_per_period * periods_per_buffer));
 787	}
 788
 789	ret = ret && (ep->datainterval == fmt->datainterval);
 790	ret = ret && (ep->maxpacksize == fmt->maxpacksize);
 791	ret = ret &&
 792		(ep->fill_max == !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX));
 793
 794	return ret;
 795}
 796
 797/*
 798 * configure a data endpoint
 799 */
 800static int data_ep_set_params(struct snd_usb_endpoint *ep,
 801			      snd_pcm_format_t pcm_format,
 802			      unsigned int channels,
 803			      unsigned int period_bytes,
 804			      unsigned int frames_per_period,
 805			      unsigned int periods_per_buffer,
 806			      struct audioformat *fmt,
 807			      struct snd_usb_endpoint *sync_ep)
 808{
 809	unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
 810	unsigned int max_packs_per_period, urbs_per_period, urb_packs;
 811	unsigned int max_urbs, i;
 812	int frame_bits = snd_pcm_format_physical_width(pcm_format) * channels;
 813	int tx_length_quirk = (ep->chip->tx_length_quirk &&
 814			       usb_pipeout(ep->pipe));
 815
 816	if (pcm_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
 817		/*
 818		 * When operating in DSD DOP mode, the size of a sample frame
 819		 * in hardware differs from the actual physical format width
 820		 * because we need to make room for the DOP markers.
 821		 */
 822		frame_bits += channels << 3;
 823	}
 824
 825	ep->datainterval = fmt->datainterval;
 826	ep->stride = frame_bits >> 3;
 827
 828	switch (pcm_format) {
 829	case SNDRV_PCM_FORMAT_U8:
 830		ep->silence_value = 0x80;
 831		break;
 832	case SNDRV_PCM_FORMAT_DSD_U8:
 833	case SNDRV_PCM_FORMAT_DSD_U16_LE:
 834	case SNDRV_PCM_FORMAT_DSD_U32_LE:
 835	case SNDRV_PCM_FORMAT_DSD_U16_BE:
 836	case SNDRV_PCM_FORMAT_DSD_U32_BE:
 837		ep->silence_value = 0x69;
 838		break;
 839	default:
 840		ep->silence_value = 0;
 841	}
 842
 843	/* assume max. frequency is 50% higher than nominal */
 844	ep->freqmax = ep->freqn + (ep->freqn >> 1);
 845	/* Round up freqmax to nearest integer in order to calculate maximum
 846	 * packet size, which must represent a whole number of frames.
 847	 * This is accomplished by adding 0x0.ffff before converting the
 848	 * Q16.16 format into integer.
 849	 * In order to accurately calculate the maximum packet size when
 850	 * the data interval is more than 1 (i.e. ep->datainterval > 0),
 851	 * multiply by the data interval prior to rounding. For instance,
 852	 * a freqmax of 41 kHz will result in a max packet size of 6 (5.125)
 853	 * frames with a data interval of 1, but 11 (10.25) frames with a
 854	 * data interval of 2.
 855	 * (ep->freqmax << ep->datainterval overflows at 8.192 MHz for the
 856	 * maximum datainterval value of 3, at USB full speed, higher for
 857	 * USB high speed, noting that ep->freqmax is in units of
 858	 * frames per packet in Q16.16 format.)
 859	 */
 860	maxsize = (((ep->freqmax << ep->datainterval) + 0xffff) >> 16) *
 861			 (frame_bits >> 3);
 862	if (tx_length_quirk)
 863		maxsize += sizeof(__le32); /* Space for length descriptor */
 864	/* but wMaxPacketSize might reduce this */
 865	if (ep->maxpacksize && ep->maxpacksize < maxsize) {
 866		/* whatever fits into a max. size packet */
 867		unsigned int data_maxsize = maxsize = ep->maxpacksize;
 868
 869		if (tx_length_quirk)
 870			/* Need to remove the length descriptor to calc freq */
 871			data_maxsize -= sizeof(__le32);
 872		ep->freqmax = (data_maxsize / (frame_bits >> 3))
 873				<< (16 - ep->datainterval);
 874	}
 875
 876	if (ep->fill_max)
 877		ep->curpacksize = ep->maxpacksize;
 878	else
 879		ep->curpacksize = maxsize;
 880
 881	if (snd_usb_get_speed(ep->chip->dev) != USB_SPEED_FULL) {
 882		packs_per_ms = 8 >> ep->datainterval;
 883		max_packs_per_urb = MAX_PACKS_HS;
 884	} else {
 885		packs_per_ms = 1;
 886		max_packs_per_urb = MAX_PACKS;
 887	}
 888	if (sync_ep && !snd_usb_endpoint_implicit_feedback_sink(ep))
 889		max_packs_per_urb = min(max_packs_per_urb,
 890					1U << sync_ep->syncinterval);
 891	max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);
 892
 893	/*
 894	 * Capture endpoints need to use small URBs because there's no way
 895	 * to tell in advance where the next period will end, and we don't
 896	 * want the next URB to complete much after the period ends.
 897	 *
 898	 * Playback endpoints with implicit sync much use the same parameters
 899	 * as their corresponding capture endpoint.
 900	 */
 901	if (usb_pipein(ep->pipe) ||
 902			snd_usb_endpoint_implicit_feedback_sink(ep)) {
 903
 904		urb_packs = packs_per_ms;
 905		/*
 906		 * Wireless devices can poll at a max rate of once per 4ms.
 907		 * For dataintervals less than 5, increase the packet count to
 908		 * allow the host controller to use bursting to fill in the
 909		 * gaps.
 910		 */
 911		if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_WIRELESS) {
 912			int interval = ep->datainterval;
 913			while (interval < 5) {
 914				urb_packs <<= 1;
 915				++interval;
 916			}
 917		}
 918		/* make capture URBs <= 1 ms and smaller than a period */
 919		urb_packs = min(max_packs_per_urb, urb_packs);
 920		while (urb_packs > 1 && urb_packs * maxsize >= period_bytes)
 921			urb_packs >>= 1;
 922		ep->nurbs = MAX_URBS;
 923
 924	/*
 925	 * Playback endpoints without implicit sync are adjusted so that
 926	 * a period fits as evenly as possible in the smallest number of
 927	 * URBs.  The total number of URBs is adjusted to the size of the
 928	 * ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
 929	 */
 930	} else {
 931		/* determine how small a packet can be */
 932		minsize = (ep->freqn >> (16 - ep->datainterval)) *
 933				(frame_bits >> 3);
 934		/* with sync from device, assume it can be 12% lower */
 935		if (sync_ep)
 936			minsize -= minsize >> 3;
 937		minsize = max(minsize, 1u);
 938
 939		/* how many packets will contain an entire ALSA period? */
 940		max_packs_per_period = DIV_ROUND_UP(period_bytes, minsize);
 941
 942		/* how many URBs will contain a period? */
 943		urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
 944				max_packs_per_urb);
 945		/* how many packets are needed in each URB? */
 946		urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);
 947
 948		/* limit the number of frames in a single URB */
 949		ep->max_urb_frames = DIV_ROUND_UP(frames_per_period,
 950					urbs_per_period);
 951
 952		/* try to use enough URBs to contain an entire ALSA buffer */
 953		max_urbs = min((unsigned) MAX_URBS,
 954				MAX_QUEUE * packs_per_ms / urb_packs);
 955		ep->nurbs = min(max_urbs, urbs_per_period * periods_per_buffer);
 956	}
 957
 958	/* allocate and initialize data urbs */
 959	for (i = 0; i < ep->nurbs; i++) {
 960		struct snd_urb_ctx *u = &ep->urb[i];
 961		u->index = i;
 962		u->ep = ep;
 963		u->packets = urb_packs;
 964		u->buffer_size = maxsize * u->packets;
 965
 966		if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
 967			u->packets++; /* for transfer delimiter */
 968		u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
 969		if (!u->urb)
 970			goto out_of_memory;
 971
 972		u->urb->transfer_buffer =
 973			usb_alloc_coherent(ep->chip->dev, u->buffer_size,
 974					   GFP_KERNEL, &u->urb->transfer_dma);
 975		if (!u->urb->transfer_buffer)
 976			goto out_of_memory;
 977		u->urb->pipe = ep->pipe;
 978		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
 979		u->urb->interval = 1 << ep->datainterval;
 980		u->urb->context = u;
 981		u->urb->complete = snd_complete_urb;
 982		INIT_LIST_HEAD(&u->ready_list);
 983	}
 984
 985	return 0;
 986
 987out_of_memory:
 988	release_urbs(ep, 0);
 989	return -ENOMEM;
 990}
 991
 992/*
 993 * configure a sync endpoint
 994 */
 995static int sync_ep_set_params(struct snd_usb_endpoint *ep)
 996{
 997	int i;
 998
 999	ep->syncbuf = usb_alloc_coherent(ep->chip->dev, SYNC_URBS * 4,
1000					 GFP_KERNEL, &ep->sync_dma);
1001	if (!ep->syncbuf)
1002		return -ENOMEM;
1003
1004	for (i = 0; i < SYNC_URBS; i++) {
1005		struct snd_urb_ctx *u = &ep->urb[i];
1006		u->index = i;
1007		u->ep = ep;
1008		u->packets = 1;
1009		u->urb = usb_alloc_urb(1, GFP_KERNEL);
1010		if (!u->urb)
1011			goto out_of_memory;
1012		u->urb->transfer_buffer = ep->syncbuf + i * 4;
1013		u->urb->transfer_dma = ep->sync_dma + i * 4;
1014		u->urb->transfer_buffer_length = 4;
1015		u->urb->pipe = ep->pipe;
1016		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1017		u->urb->number_of_packets = 1;
1018		u->urb->interval = 1 << ep->syncinterval;
1019		u->urb->context = u;
1020		u->urb->complete = snd_complete_urb;
1021	}
1022
1023	ep->nurbs = SYNC_URBS;
1024
1025	return 0;
1026
1027out_of_memory:
1028	release_urbs(ep, 0);
1029	return -ENOMEM;
1030}
1031
1032/**
1033 * snd_usb_endpoint_set_params: configure an snd_usb_endpoint
1034 *
1035 * @ep: the snd_usb_endpoint to configure
1036 * @pcm_format: the audio fomat.
1037 * @channels: the number of audio channels.
1038 * @period_bytes: the number of bytes in one alsa period.
1039 * @period_frames: the number of frames in one alsa period.
1040 * @buffer_periods: the number of periods in one alsa buffer.
1041 * @rate: the frame rate.
1042 * @fmt: the USB audio format information
1043 * @sync_ep: the sync endpoint to use, if any
1044 *
1045 * Determine the number of URBs to be used on this endpoint.
1046 * An endpoint must be configured before it can be started.
1047 * An endpoint that is already running can not be reconfigured.
1048 */
1049int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
1050				snd_pcm_format_t pcm_format,
1051				unsigned int channels,
1052				unsigned int period_bytes,
1053				unsigned int period_frames,
1054				unsigned int buffer_periods,
1055				unsigned int rate,
1056				struct audioformat *fmt,
1057				struct snd_usb_endpoint *sync_ep)
1058{
1059	int err;
1060
1061	if (ep->use_count != 0) {
1062		bool check = ep->is_implicit_feedback &&
1063			check_ep_params(ep, pcm_format,
1064					     channels, period_bytes,
1065					     period_frames, buffer_periods,
1066					     fmt, sync_ep);
1067
1068		if (!check) {
1069			usb_audio_warn(ep->chip,
1070				"Unable to change format on ep #%x: already in use\n",
1071				ep->ep_num);
1072			return -EBUSY;
1073		}
1074
1075		usb_audio_dbg(ep->chip,
1076			      "Ep #%x already in use as implicit feedback but format not changed\n",
1077			      ep->ep_num);
1078		return 0;
1079	}
1080
1081	/* release old buffers, if any */
1082	release_urbs(ep, 0);
1083
1084	ep->datainterval = fmt->datainterval;
1085	ep->maxpacksize = fmt->maxpacksize;
1086	ep->fill_max = !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX);
1087
1088	if (snd_usb_get_speed(ep->chip->dev) == USB_SPEED_FULL) {
1089		ep->freqn = get_usb_full_speed_rate(rate);
1090		ep->pps = 1000 >> ep->datainterval;
1091	} else {
1092		ep->freqn = get_usb_high_speed_rate(rate);
1093		ep->pps = 8000 >> ep->datainterval;
1094	}
1095
1096	ep->sample_rem = rate % ep->pps;
1097	ep->packsize[0] = rate / ep->pps;
1098	ep->packsize[1] = (rate + (ep->pps - 1)) / ep->pps;
1099
1100	/* calculate the frequency in 16.16 format */
1101	ep->freqm = ep->freqn;
1102	ep->freqshift = INT_MIN;
1103
1104	ep->phase = 0;
1105
1106	switch (ep->type) {
1107	case  SND_USB_ENDPOINT_TYPE_DATA:
1108		err = data_ep_set_params(ep, pcm_format, channels,
1109					 period_bytes, period_frames,
1110					 buffer_periods, fmt, sync_ep);
1111		break;
1112	case  SND_USB_ENDPOINT_TYPE_SYNC:
1113		err = sync_ep_set_params(ep);
1114		break;
1115	default:
1116		err = -EINVAL;
1117	}
1118
1119	usb_audio_dbg(ep->chip,
1120		"Setting params for ep #%x (type %d, %d urbs), ret=%d\n",
1121		ep->ep_num, ep->type, ep->nurbs, err);
1122
1123	return err;
1124}
1125
1126/**
1127 * snd_usb_endpoint_start: start an snd_usb_endpoint
1128 *
1129 * @ep: the endpoint to start
1130 *
1131 * A call to this function will increment the use count of the endpoint.
1132 * In case it is not already running, the URBs for this endpoint will be
1133 * submitted. Otherwise, this function does nothing.
1134 *
1135 * Must be balanced to calls of snd_usb_endpoint_stop().
1136 *
1137 * Returns an error if the URB submission failed, 0 in all other cases.
1138 */
1139int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
1140{
1141	int err;
1142	unsigned int i;
1143
1144	if (atomic_read(&ep->chip->shutdown))
1145		return -EBADFD;
1146
1147	/* already running? */
1148	if (++ep->use_count != 1)
1149		return 0;
1150
1151	/* just to be sure */
1152	deactivate_urbs(ep, false);
1153
1154	ep->active_mask = 0;
1155	ep->unlink_mask = 0;
1156	ep->phase = 0;
1157	ep->sample_accum = 0;
1158
1159	snd_usb_endpoint_start_quirk(ep);
1160
1161	/*
1162	 * If this endpoint has a data endpoint as implicit feedback source,
1163	 * don't start the urbs here. Instead, mark them all as available,
1164	 * wait for the record urbs to return and queue the playback urbs
1165	 * from that context.
1166	 */
1167
1168	set_bit(EP_FLAG_RUNNING, &ep->flags);
1169
1170	if (snd_usb_endpoint_implicit_feedback_sink(ep)) {
1171		for (i = 0; i < ep->nurbs; i++) {
1172			struct snd_urb_ctx *ctx = ep->urb + i;
1173			list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
1174		}
1175
1176		return 0;
1177	}
1178
1179	for (i = 0; i < ep->nurbs; i++) {
1180		struct urb *urb = ep->urb[i].urb;
1181
1182		if (snd_BUG_ON(!urb))
1183			goto __error;
1184
1185		if (usb_pipeout(ep->pipe)) {
1186			prepare_outbound_urb(ep, urb->context);
1187		} else {
1188			prepare_inbound_urb(ep, urb->context);
1189		}
1190
1191		err = usb_submit_urb(urb, GFP_ATOMIC);
1192		if (err < 0) {
1193			usb_audio_err(ep->chip,
1194				"cannot submit urb %d, error %d: %s\n",
1195				i, err, usb_error_string(err));
1196			goto __error;
1197		}
1198		set_bit(i, &ep->active_mask);
1199	}
1200
1201	return 0;
1202
1203__error:
1204	clear_bit(EP_FLAG_RUNNING, &ep->flags);
1205	ep->use_count--;
1206	deactivate_urbs(ep, false);
1207	return -EPIPE;
1208}
1209
1210/**
1211 * snd_usb_endpoint_stop: stop an snd_usb_endpoint
1212 *
1213 * @ep: the endpoint to stop (may be NULL)
1214 *
1215 * A call to this function will decrement the use count of the endpoint.
1216 * In case the last user has requested the endpoint stop, the URBs will
1217 * actually be deactivated.
1218 *
1219 * Must be balanced to calls of snd_usb_endpoint_start().
1220 *
1221 * The caller needs to synchronize the pending stop operation via
1222 * snd_usb_endpoint_sync_pending_stop().
1223 */
1224void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep)
1225{
1226	if (!ep)
1227		return;
1228
1229	if (snd_BUG_ON(ep->use_count == 0))
1230		return;
1231
1232	if (--ep->use_count == 0) {
1233		deactivate_urbs(ep, false);
1234		set_bit(EP_FLAG_STOPPING, &ep->flags);
1235	}
1236}
1237
1238/**
1239 * snd_usb_endpoint_deactivate: deactivate an snd_usb_endpoint
1240 *
1241 * @ep: the endpoint to deactivate
1242 *
1243 * If the endpoint is not currently in use, this functions will
1244 * deactivate its associated URBs.
1245 *
1246 * In case of any active users, this functions does nothing.
1247 */
1248void snd_usb_endpoint_deactivate(struct snd_usb_endpoint *ep)
1249{
1250	if (!ep)
1251		return;
1252
1253	if (ep->use_count != 0)
1254		return;
1255
1256	deactivate_urbs(ep, true);
1257	wait_clear_urbs(ep);
1258}
1259
1260/**
1261 * snd_usb_endpoint_release: Tear down an snd_usb_endpoint
1262 *
1263 * @ep: the endpoint to release
1264 *
1265 * This function does not care for the endpoint's use count but will tear
1266 * down all the streaming URBs immediately.
1267 */
1268void snd_usb_endpoint_release(struct snd_usb_endpoint *ep)
1269{
1270	release_urbs(ep, 1);
1271}
1272
1273/**
1274 * snd_usb_endpoint_free: Free the resources of an snd_usb_endpoint
1275 *
1276 * @ep: the endpoint to free
1277 *
1278 * This free all resources of the given ep.
1279 */
1280void snd_usb_endpoint_free(struct snd_usb_endpoint *ep)
1281{
1282	kfree(ep);
1283}
1284
1285/**
1286 * snd_usb_handle_sync_urb: parse an USB sync packet
1287 *
1288 * @ep: the endpoint to handle the packet
1289 * @sender: the sending endpoint
1290 * @urb: the received packet
1291 *
1292 * This function is called from the context of an endpoint that received
1293 * the packet and is used to let another endpoint object handle the payload.
1294 */
1295void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
1296			     struct snd_usb_endpoint *sender,
1297			     const struct urb *urb)
1298{
1299	int shift;
1300	unsigned int f;
1301	unsigned long flags;
1302
1303	snd_BUG_ON(ep == sender);
1304
1305	/*
1306	 * In case the endpoint is operating in implicit feedback mode, prepare
1307	 * a new outbound URB that has the same layout as the received packet
1308	 * and add it to the list of pending urbs. queue_pending_output_urbs()
1309	 * will take care of them later.
1310	 */
1311	if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
1312	    ep->use_count != 0) {
1313
1314		/* implicit feedback case */
1315		int i, bytes = 0;
1316		struct snd_urb_ctx *in_ctx;
1317		struct snd_usb_packet_info *out_packet;
1318
1319		in_ctx = urb->context;
1320
1321		/* Count overall packet size */
1322		for (i = 0; i < in_ctx->packets; i++)
1323			if (urb->iso_frame_desc[i].status == 0)
1324				bytes += urb->iso_frame_desc[i].actual_length;
1325
1326		/*
1327		 * skip empty packets. At least M-Audio's Fast Track Ultra stops
1328		 * streaming once it received a 0-byte OUT URB
1329		 */
1330		if (bytes == 0)
1331			return;
1332
1333		spin_lock_irqsave(&ep->lock, flags);
1334		out_packet = ep->next_packet + ep->next_packet_write_pos;
1335
1336		/*
1337		 * Iterate through the inbound packet and prepare the lengths
1338		 * for the output packet. The OUT packet we are about to send
1339		 * will have the same amount of payload bytes per stride as the
1340		 * IN packet we just received. Since the actual size is scaled
1341		 * by the stride, use the sender stride to calculate the length
1342		 * in case the number of channels differ between the implicitly
1343		 * fed-back endpoint and the synchronizing endpoint.
1344		 */
1345
1346		out_packet->packets = in_ctx->packets;
1347		for (i = 0; i < in_ctx->packets; i++) {
1348			if (urb->iso_frame_desc[i].status == 0)
1349				out_packet->packet_size[i] =
1350					urb->iso_frame_desc[i].actual_length / sender->stride;
1351			else
1352				out_packet->packet_size[i] = 0;
1353		}
1354
1355		ep->next_packet_write_pos++;
1356		ep->next_packet_write_pos %= MAX_URBS;
1357		spin_unlock_irqrestore(&ep->lock, flags);
1358		queue_pending_output_urbs(ep);
1359
1360		return;
1361	}
1362
1363	/*
1364	 * process after playback sync complete
1365	 *
1366	 * Full speed devices report feedback values in 10.14 format as samples
1367	 * per frame, high speed devices in 16.16 format as samples per
1368	 * microframe.
1369	 *
1370	 * Because the Audio Class 1 spec was written before USB 2.0, many high
1371	 * speed devices use a wrong interpretation, some others use an
1372	 * entirely different format.
1373	 *
1374	 * Therefore, we cannot predict what format any particular device uses
1375	 * and must detect it automatically.
1376	 */
1377
1378	if (urb->iso_frame_desc[0].status != 0 ||
1379	    urb->iso_frame_desc[0].actual_length < 3)
1380		return;
1381
1382	f = le32_to_cpup(urb->transfer_buffer);
1383	if (urb->iso_frame_desc[0].actual_length == 3)
1384		f &= 0x00ffffff;
1385	else
1386		f &= 0x0fffffff;
1387
1388	if (f == 0)
1389		return;
1390
1391	if (unlikely(sender->tenor_fb_quirk)) {
1392		/*
1393		 * Devices based on Tenor 8802 chipsets (TEAC UD-H01
1394		 * and others) sometimes change the feedback value
1395		 * by +/- 0x1.0000.
1396		 */
1397		if (f < ep->freqn - 0x8000)
1398			f += 0xf000;
1399		else if (f > ep->freqn + 0x8000)
1400			f -= 0xf000;
1401	} else if (unlikely(ep->freqshift == INT_MIN)) {
1402		/*
1403		 * The first time we see a feedback value, determine its format
1404		 * by shifting it left or right until it matches the nominal
1405		 * frequency value.  This assumes that the feedback does not
1406		 * differ from the nominal value more than +50% or -25%.
1407		 */
1408		shift = 0;
1409		while (f < ep->freqn - ep->freqn / 4) {
1410			f <<= 1;
1411			shift++;
1412		}
1413		while (f > ep->freqn + ep->freqn / 2) {
1414			f >>= 1;
1415			shift--;
1416		}
1417		ep->freqshift = shift;
1418	} else if (ep->freqshift >= 0)
1419		f <<= ep->freqshift;
1420	else
1421		f >>= -ep->freqshift;
1422
1423	if (likely(f >= ep->freqn - ep->freqn / 8 && f <= ep->freqmax)) {
1424		/*
1425		 * If the frequency looks valid, set it.
1426		 * This value is referred to in prepare_playback_urb().
1427		 */
1428		spin_lock_irqsave(&ep->lock, flags);
1429		ep->freqm = f;
1430		spin_unlock_irqrestore(&ep->lock, flags);
1431	} else {
1432		/*
1433		 * Out of range; maybe the shift value is wrong.
1434		 * Reset it so that we autodetect again the next time.
1435		 */
1436		ep->freqshift = INT_MIN;
1437	}
1438}
1439