xref: /linux/sound/usb/endpoint.c (revision e1c4c5436b4ad579762fbe78bfabc8aef59bd5b1)
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 "clock.h"
22 #include "quirks.h"
23 
24 enum {
25 	EP_STATE_STOPPED,
26 	EP_STATE_RUNNING,
27 	EP_STATE_STOPPING,
28 };
29 
30 /* interface refcounting */
31 struct snd_usb_iface_ref {
32 	unsigned char iface;
33 	bool need_setup;
34 	int opened;
35 	int altset;
36 	struct list_head list;
37 };
38 
39 /* clock refcounting */
40 struct snd_usb_clock_ref {
41 	unsigned char clock;
42 	atomic_t locked;
43 	int opened;
44 	int rate;
45 	bool need_setup;
46 	struct list_head list;
47 };
48 
49 /*
50  * snd_usb_endpoint is a model that abstracts everything related to an
51  * USB endpoint and its streaming.
52  *
53  * There are functions to activate and deactivate the streaming URBs and
54  * optional callbacks to let the pcm logic handle the actual content of the
55  * packets for playback and record. Thus, the bus streaming and the audio
56  * handlers are fully decoupled.
57  *
58  * There are two different types of endpoints in audio applications.
59  *
60  * SND_USB_ENDPOINT_TYPE_DATA handles full audio data payload for both
61  * inbound and outbound traffic.
62  *
63  * SND_USB_ENDPOINT_TYPE_SYNC endpoints are for inbound traffic only and
64  * expect the payload to carry Q10.14 / Q16.16 formatted sync information
65  * (3 or 4 bytes).
66  *
67  * Each endpoint has to be configured prior to being used by calling
68  * snd_usb_endpoint_set_params().
69  *
70  * The model incorporates a reference counting, so that multiple users
71  * can call snd_usb_endpoint_start() and snd_usb_endpoint_stop(), and
72  * only the first user will effectively start the URBs, and only the last
73  * one to stop it will tear the URBs down again.
74  */
75 
76 /*
77  * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
78  * this will overflow at approx 524 kHz
79  */
80 static inline unsigned get_usb_full_speed_rate(unsigned int rate)
81 {
82 	return ((rate << 13) + 62) / 125;
83 }
84 
85 /*
86  * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
87  * this will overflow at approx 4 MHz
88  */
89 static inline unsigned get_usb_high_speed_rate(unsigned int rate)
90 {
91 	return ((rate << 10) + 62) / 125;
92 }
93 
94 /*
95  * release a urb data
96  */
97 static void release_urb_ctx(struct snd_urb_ctx *u)
98 {
99 	if (u->urb && u->buffer_size)
100 		usb_free_coherent(u->ep->chip->dev, u->buffer_size,
101 				  u->urb->transfer_buffer,
102 				  u->urb->transfer_dma);
103 	usb_free_urb(u->urb);
104 	u->urb = NULL;
105 	u->buffer_size = 0;
106 }
107 
108 static const char *usb_error_string(int err)
109 {
110 	switch (err) {
111 	case -ENODEV:
112 		return "no device";
113 	case -ENOENT:
114 		return "endpoint not enabled";
115 	case -EPIPE:
116 		return "endpoint stalled";
117 	case -ENOSPC:
118 		return "not enough bandwidth";
119 	case -ESHUTDOWN:
120 		return "device disabled";
121 	case -EHOSTUNREACH:
122 		return "device suspended";
123 	case -EINVAL:
124 	case -EAGAIN:
125 	case -EFBIG:
126 	case -EMSGSIZE:
127 		return "internal error";
128 	default:
129 		return "unknown error";
130 	}
131 }
132 
133 static inline bool ep_state_running(struct snd_usb_endpoint *ep)
134 {
135 	return atomic_read(&ep->state) == EP_STATE_RUNNING;
136 }
137 
138 static inline bool ep_state_update(struct snd_usb_endpoint *ep, int old, int new)
139 {
140 	return atomic_try_cmpxchg(&ep->state, &old, new);
141 }
142 
143 /**
144  * snd_usb_endpoint_implicit_feedback_sink: Report endpoint usage type
145  *
146  * @ep: The snd_usb_endpoint
147  *
148  * Determine whether an endpoint is driven by an implicit feedback
149  * data endpoint source.
150  */
151 int snd_usb_endpoint_implicit_feedback_sink(struct snd_usb_endpoint *ep)
152 {
153 	return  ep->implicit_fb_sync && usb_pipeout(ep->pipe);
154 }
155 
156 /*
157  * Return the number of samples to be sent in the next packet
158  * for streaming based on information derived from sync endpoints
159  *
160  * This won't be used for implicit feedback which takes the packet size
161  * returned from the sync source
162  */
163 static int slave_next_packet_size(struct snd_usb_endpoint *ep,
164 				  unsigned int avail)
165 {
166 	unsigned long flags;
167 	unsigned int phase;
168 	int ret;
169 
170 	if (ep->fill_max)
171 		return ep->maxframesize;
172 
173 	spin_lock_irqsave(&ep->lock, flags);
174 	phase = (ep->phase & 0xffff) + (ep->freqm << ep->datainterval);
175 	ret = min(phase >> 16, ep->maxframesize);
176 	if (avail && ret >= avail)
177 		ret = -EAGAIN;
178 	else
179 		ep->phase = phase;
180 	spin_unlock_irqrestore(&ep->lock, flags);
181 
182 	return ret;
183 }
184 
185 /*
186  * Return the number of samples to be sent in the next packet
187  * for adaptive and synchronous endpoints
188  */
189 static int next_packet_size(struct snd_usb_endpoint *ep, unsigned int avail)
190 {
191 	unsigned int sample_accum;
192 	int ret;
193 
194 	if (ep->fill_max)
195 		return ep->maxframesize;
196 
197 	sample_accum = ep->sample_accum + ep->sample_rem;
198 	if (sample_accum >= ep->pps) {
199 		sample_accum -= ep->pps;
200 		ret = ep->packsize[1];
201 	} else {
202 		ret = ep->packsize[0];
203 	}
204 	if (avail && ret >= avail)
205 		ret = -EAGAIN;
206 	else
207 		ep->sample_accum = sample_accum;
208 
209 	return ret;
210 }
211 
212 /*
213  * snd_usb_endpoint_next_packet_size: Return the number of samples to be sent
214  * in the next packet
215  *
216  * If the size is equal or exceeds @avail, don't proceed but return -EAGAIN
217  * Exception: @avail = 0 for skipping the check.
218  */
219 int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep,
220 				      struct snd_urb_ctx *ctx, int idx,
221 				      unsigned int avail)
222 {
223 	unsigned int packet;
224 
225 	packet = ctx->packet_size[idx];
226 	if (packet) {
227 		if (avail && packet >= avail)
228 			return -EAGAIN;
229 		return packet;
230 	}
231 
232 	if (ep->sync_source)
233 		return slave_next_packet_size(ep, avail);
234 	else
235 		return next_packet_size(ep, avail);
236 }
237 
238 static void call_retire_callback(struct snd_usb_endpoint *ep,
239 				 struct urb *urb)
240 {
241 	struct snd_usb_substream *data_subs;
242 
243 	data_subs = READ_ONCE(ep->data_subs);
244 	if (data_subs && ep->retire_data_urb)
245 		ep->retire_data_urb(data_subs, urb);
246 }
247 
248 static void retire_outbound_urb(struct snd_usb_endpoint *ep,
249 				struct snd_urb_ctx *urb_ctx)
250 {
251 	call_retire_callback(ep, urb_ctx->urb);
252 }
253 
254 static void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
255 				    struct snd_usb_endpoint *sender,
256 				    const struct urb *urb);
257 
258 static void retire_inbound_urb(struct snd_usb_endpoint *ep,
259 			       struct snd_urb_ctx *urb_ctx)
260 {
261 	struct urb *urb = urb_ctx->urb;
262 	struct snd_usb_endpoint *sync_sink;
263 
264 	if (unlikely(ep->skip_packets > 0)) {
265 		ep->skip_packets--;
266 		return;
267 	}
268 
269 	sync_sink = READ_ONCE(ep->sync_sink);
270 	if (sync_sink)
271 		snd_usb_handle_sync_urb(sync_sink, ep, urb);
272 
273 	call_retire_callback(ep, urb);
274 }
275 
276 static inline bool has_tx_length_quirk(struct snd_usb_audio *chip)
277 {
278 	return chip->quirk_flags & QUIRK_FLAG_TX_LENGTH;
279 }
280 
281 static void prepare_silent_urb(struct snd_usb_endpoint *ep,
282 			       struct snd_urb_ctx *ctx)
283 {
284 	struct urb *urb = ctx->urb;
285 	unsigned int offs = 0;
286 	unsigned int extra = 0;
287 	__le32 packet_length;
288 	int i;
289 
290 	/* For tx_length_quirk, put packet length at start of packet */
291 	if (has_tx_length_quirk(ep->chip))
292 		extra = sizeof(packet_length);
293 
294 	for (i = 0; i < ctx->packets; ++i) {
295 		unsigned int offset;
296 		unsigned int length;
297 		int counts;
298 
299 		counts = snd_usb_endpoint_next_packet_size(ep, ctx, i, 0);
300 		length = counts * ep->stride; /* number of silent bytes */
301 		offset = offs * ep->stride + extra * i;
302 		urb->iso_frame_desc[i].offset = offset;
303 		urb->iso_frame_desc[i].length = length + extra;
304 		if (extra) {
305 			packet_length = cpu_to_le32(length);
306 			memcpy(urb->transfer_buffer + offset,
307 			       &packet_length, sizeof(packet_length));
308 		}
309 		memset(urb->transfer_buffer + offset + extra,
310 		       ep->silence_value, length);
311 		offs += counts;
312 	}
313 
314 	urb->number_of_packets = ctx->packets;
315 	urb->transfer_buffer_length = offs * ep->stride + ctx->packets * extra;
316 	ctx->queued = 0;
317 }
318 
319 /*
320  * Prepare a PLAYBACK urb for submission to the bus.
321  */
322 static int prepare_outbound_urb(struct snd_usb_endpoint *ep,
323 				struct snd_urb_ctx *ctx,
324 				bool in_stream_lock)
325 {
326 	struct urb *urb = ctx->urb;
327 	unsigned char *cp = urb->transfer_buffer;
328 	struct snd_usb_substream *data_subs;
329 
330 	urb->dev = ep->chip->dev; /* we need to set this at each time */
331 
332 	switch (ep->type) {
333 	case SND_USB_ENDPOINT_TYPE_DATA:
334 		data_subs = READ_ONCE(ep->data_subs);
335 		if (data_subs && ep->prepare_data_urb)
336 			return ep->prepare_data_urb(data_subs, urb, in_stream_lock);
337 		/* no data provider, so send silence */
338 		prepare_silent_urb(ep, ctx);
339 		break;
340 
341 	case SND_USB_ENDPOINT_TYPE_SYNC:
342 		if (snd_usb_get_speed(ep->chip->dev) >= USB_SPEED_HIGH) {
343 			/*
344 			 * fill the length and offset of each urb descriptor.
345 			 * the fixed 12.13 frequency is passed as 16.16 through the pipe.
346 			 */
347 			urb->iso_frame_desc[0].length = 4;
348 			urb->iso_frame_desc[0].offset = 0;
349 			cp[0] = ep->freqn;
350 			cp[1] = ep->freqn >> 8;
351 			cp[2] = ep->freqn >> 16;
352 			cp[3] = ep->freqn >> 24;
353 		} else {
354 			/*
355 			 * fill the length and offset of each urb descriptor.
356 			 * the fixed 10.14 frequency is passed through the pipe.
357 			 */
358 			urb->iso_frame_desc[0].length = 3;
359 			urb->iso_frame_desc[0].offset = 0;
360 			cp[0] = ep->freqn >> 2;
361 			cp[1] = ep->freqn >> 10;
362 			cp[2] = ep->freqn >> 18;
363 		}
364 
365 		break;
366 	}
367 	return 0;
368 }
369 
370 /*
371  * Prepare a CAPTURE or SYNC urb for submission to the bus.
372  */
373 static int prepare_inbound_urb(struct snd_usb_endpoint *ep,
374 			       struct snd_urb_ctx *urb_ctx)
375 {
376 	int i, offs;
377 	struct urb *urb = urb_ctx->urb;
378 
379 	urb->dev = ep->chip->dev; /* we need to set this at each time */
380 
381 	switch (ep->type) {
382 	case SND_USB_ENDPOINT_TYPE_DATA:
383 		offs = 0;
384 		for (i = 0; i < urb_ctx->packets; i++) {
385 			urb->iso_frame_desc[i].offset = offs;
386 			urb->iso_frame_desc[i].length = ep->curpacksize;
387 			offs += ep->curpacksize;
388 		}
389 
390 		urb->transfer_buffer_length = offs;
391 		urb->number_of_packets = urb_ctx->packets;
392 		break;
393 
394 	case SND_USB_ENDPOINT_TYPE_SYNC:
395 		urb->iso_frame_desc[0].length = min(4u, ep->syncmaxsize);
396 		urb->iso_frame_desc[0].offset = 0;
397 		break;
398 	}
399 	return 0;
400 }
401 
402 /* notify an error as XRUN to the assigned PCM data substream */
403 static void notify_xrun(struct snd_usb_endpoint *ep)
404 {
405 	struct snd_usb_substream *data_subs;
406 
407 	data_subs = READ_ONCE(ep->data_subs);
408 	if (data_subs && data_subs->pcm_substream)
409 		snd_pcm_stop_xrun(data_subs->pcm_substream);
410 }
411 
412 static struct snd_usb_packet_info *
413 next_packet_fifo_enqueue(struct snd_usb_endpoint *ep)
414 {
415 	struct snd_usb_packet_info *p;
416 
417 	p = ep->next_packet + (ep->next_packet_head + ep->next_packet_queued) %
418 		ARRAY_SIZE(ep->next_packet);
419 	ep->next_packet_queued++;
420 	return p;
421 }
422 
423 static struct snd_usb_packet_info *
424 next_packet_fifo_dequeue(struct snd_usb_endpoint *ep)
425 {
426 	struct snd_usb_packet_info *p;
427 
428 	p = ep->next_packet + ep->next_packet_head;
429 	ep->next_packet_head++;
430 	ep->next_packet_head %= ARRAY_SIZE(ep->next_packet);
431 	ep->next_packet_queued--;
432 	return p;
433 }
434 
435 static void push_back_to_ready_list(struct snd_usb_endpoint *ep,
436 				    struct snd_urb_ctx *ctx)
437 {
438 	unsigned long flags;
439 
440 	spin_lock_irqsave(&ep->lock, flags);
441 	list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
442 	spin_unlock_irqrestore(&ep->lock, flags);
443 }
444 
445 /*
446  * Send output urbs that have been prepared previously. URBs are dequeued
447  * from ep->ready_playback_urbs and in case there aren't any available
448  * or there are no packets that have been prepared, this function does
449  * nothing.
450  *
451  * The reason why the functionality of sending and preparing URBs is separated
452  * is that host controllers don't guarantee the order in which they return
453  * inbound and outbound packets to their submitters.
454  *
455  * This function is used both for implicit feedback endpoints and in low-
456  * latency playback mode.
457  */
458 void snd_usb_queue_pending_output_urbs(struct snd_usb_endpoint *ep,
459 				       bool in_stream_lock)
460 {
461 	bool implicit_fb = snd_usb_endpoint_implicit_feedback_sink(ep);
462 
463 	while (ep_state_running(ep)) {
464 
465 		unsigned long flags;
466 		struct snd_usb_packet_info *packet;
467 		struct snd_urb_ctx *ctx = NULL;
468 		int err, i;
469 
470 		spin_lock_irqsave(&ep->lock, flags);
471 		if ((!implicit_fb || ep->next_packet_queued > 0) &&
472 		    !list_empty(&ep->ready_playback_urbs)) {
473 			/* take URB out of FIFO */
474 			ctx = list_first_entry(&ep->ready_playback_urbs,
475 					       struct snd_urb_ctx, ready_list);
476 			list_del_init(&ctx->ready_list);
477 			if (implicit_fb)
478 				packet = next_packet_fifo_dequeue(ep);
479 		}
480 		spin_unlock_irqrestore(&ep->lock, flags);
481 
482 		if (ctx == NULL)
483 			return;
484 
485 		/* copy over the length information */
486 		if (implicit_fb) {
487 			for (i = 0; i < packet->packets; i++)
488 				ctx->packet_size[i] = packet->packet_size[i];
489 		}
490 
491 		/* call the data handler to fill in playback data */
492 		err = prepare_outbound_urb(ep, ctx, in_stream_lock);
493 		/* can be stopped during prepare callback */
494 		if (unlikely(!ep_state_running(ep)))
495 			break;
496 		if (err < 0) {
497 			/* push back to ready list again for -EAGAIN */
498 			if (err == -EAGAIN)
499 				push_back_to_ready_list(ep, ctx);
500 			else
501 				notify_xrun(ep);
502 			return;
503 		}
504 
505 		err = usb_submit_urb(ctx->urb, GFP_ATOMIC);
506 		if (err < 0) {
507 			usb_audio_err(ep->chip,
508 				      "Unable to submit urb #%d: %d at %s\n",
509 				      ctx->index, err, __func__);
510 			notify_xrun(ep);
511 			return;
512 		}
513 
514 		set_bit(ctx->index, &ep->active_mask);
515 		atomic_inc(&ep->submitted_urbs);
516 	}
517 }
518 
519 /*
520  * complete callback for urbs
521  */
522 static void snd_complete_urb(struct urb *urb)
523 {
524 	struct snd_urb_ctx *ctx = urb->context;
525 	struct snd_usb_endpoint *ep = ctx->ep;
526 	int err;
527 
528 	if (unlikely(urb->status == -ENOENT ||		/* unlinked */
529 		     urb->status == -ENODEV ||		/* device removed */
530 		     urb->status == -ECONNRESET ||	/* unlinked */
531 		     urb->status == -ESHUTDOWN))	/* device disabled */
532 		goto exit_clear;
533 	/* device disconnected */
534 	if (unlikely(atomic_read(&ep->chip->shutdown)))
535 		goto exit_clear;
536 
537 	if (unlikely(!ep_state_running(ep)))
538 		goto exit_clear;
539 
540 	if (usb_pipeout(ep->pipe)) {
541 		retire_outbound_urb(ep, ctx);
542 		/* can be stopped during retire callback */
543 		if (unlikely(!ep_state_running(ep)))
544 			goto exit_clear;
545 
546 		/* in low-latency and implicit-feedback modes, push back the
547 		 * URB to ready list at first, then process as much as possible
548 		 */
549 		if (ep->lowlatency_playback ||
550 		     snd_usb_endpoint_implicit_feedback_sink(ep)) {
551 			push_back_to_ready_list(ep, ctx);
552 			clear_bit(ctx->index, &ep->active_mask);
553 			snd_usb_queue_pending_output_urbs(ep, false);
554 			atomic_dec(&ep->submitted_urbs); /* decrement at last */
555 			return;
556 		}
557 
558 		/* in non-lowlatency mode, no error handling for prepare */
559 		prepare_outbound_urb(ep, ctx, false);
560 		/* can be stopped during prepare callback */
561 		if (unlikely(!ep_state_running(ep)))
562 			goto exit_clear;
563 	} else {
564 		retire_inbound_urb(ep, ctx);
565 		/* can be stopped during retire callback */
566 		if (unlikely(!ep_state_running(ep)))
567 			goto exit_clear;
568 
569 		prepare_inbound_urb(ep, ctx);
570 	}
571 
572 	err = usb_submit_urb(urb, GFP_ATOMIC);
573 	if (err == 0)
574 		return;
575 
576 	usb_audio_err(ep->chip, "cannot submit urb (err = %d)\n", err);
577 	notify_xrun(ep);
578 
579 exit_clear:
580 	clear_bit(ctx->index, &ep->active_mask);
581 	atomic_dec(&ep->submitted_urbs);
582 }
583 
584 /*
585  * Find or create a refcount object for the given interface
586  *
587  * The objects are released altogether in snd_usb_endpoint_free_all()
588  */
589 static struct snd_usb_iface_ref *
590 iface_ref_find(struct snd_usb_audio *chip, int iface)
591 {
592 	struct snd_usb_iface_ref *ip;
593 
594 	list_for_each_entry(ip, &chip->iface_ref_list, list)
595 		if (ip->iface == iface)
596 			return ip;
597 
598 	ip = kzalloc(sizeof(*ip), GFP_KERNEL);
599 	if (!ip)
600 		return NULL;
601 	ip->iface = iface;
602 	list_add_tail(&ip->list, &chip->iface_ref_list);
603 	return ip;
604 }
605 
606 /* Similarly, a refcount object for clock */
607 static struct snd_usb_clock_ref *
608 clock_ref_find(struct snd_usb_audio *chip, int clock)
609 {
610 	struct snd_usb_clock_ref *ref;
611 
612 	list_for_each_entry(ref, &chip->clock_ref_list, list)
613 		if (ref->clock == clock)
614 			return ref;
615 
616 	ref = kzalloc(sizeof(*ref), GFP_KERNEL);
617 	if (!ref)
618 		return NULL;
619 	ref->clock = clock;
620 	atomic_set(&ref->locked, 0);
621 	list_add_tail(&ref->list, &chip->clock_ref_list);
622 	return ref;
623 }
624 
625 /*
626  * Get the existing endpoint object corresponding EP
627  * Returns NULL if not present.
628  */
629 struct snd_usb_endpoint *
630 snd_usb_get_endpoint(struct snd_usb_audio *chip, int ep_num)
631 {
632 	struct snd_usb_endpoint *ep;
633 
634 	list_for_each_entry(ep, &chip->ep_list, list) {
635 		if (ep->ep_num == ep_num)
636 			return ep;
637 	}
638 
639 	return NULL;
640 }
641 
642 #define ep_type_name(type) \
643 	(type == SND_USB_ENDPOINT_TYPE_DATA ? "data" : "sync")
644 
645 /**
646  * snd_usb_add_endpoint: Add an endpoint to an USB audio chip
647  *
648  * @chip: The chip
649  * @ep_num: The number of the endpoint to use
650  * @type: SND_USB_ENDPOINT_TYPE_DATA or SND_USB_ENDPOINT_TYPE_SYNC
651  *
652  * If the requested endpoint has not been added to the given chip before,
653  * a new instance is created.
654  *
655  * Returns zero on success or a negative error code.
656  *
657  * New endpoints will be added to chip->ep_list and freed by
658  * calling snd_usb_endpoint_free_all().
659  *
660  * For SND_USB_ENDPOINT_TYPE_SYNC, the caller needs to guarantee that
661  * bNumEndpoints > 1 beforehand.
662  */
663 int snd_usb_add_endpoint(struct snd_usb_audio *chip, int ep_num, int type)
664 {
665 	struct snd_usb_endpoint *ep;
666 	bool is_playback;
667 
668 	ep = snd_usb_get_endpoint(chip, ep_num);
669 	if (ep)
670 		return 0;
671 
672 	usb_audio_dbg(chip, "Creating new %s endpoint #%x\n",
673 		      ep_type_name(type),
674 		      ep_num);
675 	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
676 	if (!ep)
677 		return -ENOMEM;
678 
679 	ep->chip = chip;
680 	spin_lock_init(&ep->lock);
681 	ep->type = type;
682 	ep->ep_num = ep_num;
683 	INIT_LIST_HEAD(&ep->ready_playback_urbs);
684 	atomic_set(&ep->submitted_urbs, 0);
685 
686 	is_playback = ((ep_num & USB_ENDPOINT_DIR_MASK) == USB_DIR_OUT);
687 	ep_num &= USB_ENDPOINT_NUMBER_MASK;
688 	if (is_playback)
689 		ep->pipe = usb_sndisocpipe(chip->dev, ep_num);
690 	else
691 		ep->pipe = usb_rcvisocpipe(chip->dev, ep_num);
692 
693 	list_add_tail(&ep->list, &chip->ep_list);
694 	return 0;
695 }
696 
697 /* Set up syncinterval and maxsyncsize for a sync EP */
698 static void endpoint_set_syncinterval(struct snd_usb_audio *chip,
699 				      struct snd_usb_endpoint *ep)
700 {
701 	struct usb_host_interface *alts;
702 	struct usb_endpoint_descriptor *desc;
703 
704 	alts = snd_usb_get_host_interface(chip, ep->iface, ep->altsetting);
705 	if (!alts)
706 		return;
707 
708 	desc = get_endpoint(alts, ep->ep_idx);
709 	if (desc->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
710 	    desc->bRefresh >= 1 && desc->bRefresh <= 9)
711 		ep->syncinterval = desc->bRefresh;
712 	else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL)
713 		ep->syncinterval = 1;
714 	else if (desc->bInterval >= 1 && desc->bInterval <= 16)
715 		ep->syncinterval = desc->bInterval - 1;
716 	else
717 		ep->syncinterval = 3;
718 
719 	ep->syncmaxsize = le16_to_cpu(desc->wMaxPacketSize);
720 }
721 
722 static bool endpoint_compatible(struct snd_usb_endpoint *ep,
723 				const struct audioformat *fp,
724 				const struct snd_pcm_hw_params *params)
725 {
726 	if (!ep->opened)
727 		return false;
728 	if (ep->cur_audiofmt != fp)
729 		return false;
730 	if (ep->cur_rate != params_rate(params) ||
731 	    ep->cur_format != params_format(params) ||
732 	    ep->cur_period_frames != params_period_size(params) ||
733 	    ep->cur_buffer_periods != params_periods(params))
734 		return false;
735 	return true;
736 }
737 
738 /*
739  * Check whether the given fp and hw params are compatible with the current
740  * setup of the target EP for implicit feedback sync
741  */
742 bool snd_usb_endpoint_compatible(struct snd_usb_audio *chip,
743 				 struct snd_usb_endpoint *ep,
744 				 const struct audioformat *fp,
745 				 const struct snd_pcm_hw_params *params)
746 {
747 	bool ret;
748 
749 	mutex_lock(&chip->mutex);
750 	ret = endpoint_compatible(ep, fp, params);
751 	mutex_unlock(&chip->mutex);
752 	return ret;
753 }
754 
755 /*
756  * snd_usb_endpoint_open: Open the endpoint
757  *
758  * Called from hw_params to assign the endpoint to the substream.
759  * It's reference-counted, and only the first opener is allowed to set up
760  * arbitrary parameters.  The later opener must be compatible with the
761  * former opened parameters.
762  * The endpoint needs to be closed via snd_usb_endpoint_close() later.
763  *
764  * Note that this function doesn't configure the endpoint.  The substream
765  * needs to set it up later via snd_usb_endpoint_set_params() and
766  * snd_usb_endpoint_prepare().
767  */
768 struct snd_usb_endpoint *
769 snd_usb_endpoint_open(struct snd_usb_audio *chip,
770 		      const struct audioformat *fp,
771 		      const struct snd_pcm_hw_params *params,
772 		      bool is_sync_ep)
773 {
774 	struct snd_usb_endpoint *ep;
775 	int ep_num = is_sync_ep ? fp->sync_ep : fp->endpoint;
776 
777 	mutex_lock(&chip->mutex);
778 	ep = snd_usb_get_endpoint(chip, ep_num);
779 	if (!ep) {
780 		usb_audio_err(chip, "Cannot find EP 0x%x to open\n", ep_num);
781 		goto unlock;
782 	}
783 
784 	if (!ep->opened) {
785 		if (is_sync_ep) {
786 			ep->iface = fp->sync_iface;
787 			ep->altsetting = fp->sync_altsetting;
788 			ep->ep_idx = fp->sync_ep_idx;
789 		} else {
790 			ep->iface = fp->iface;
791 			ep->altsetting = fp->altsetting;
792 			ep->ep_idx = fp->ep_idx;
793 		}
794 		usb_audio_dbg(chip, "Open EP 0x%x, iface=%d:%d, idx=%d\n",
795 			      ep_num, ep->iface, ep->altsetting, ep->ep_idx);
796 
797 		ep->iface_ref = iface_ref_find(chip, ep->iface);
798 		if (!ep->iface_ref) {
799 			ep = NULL;
800 			goto unlock;
801 		}
802 
803 		if (fp->protocol != UAC_VERSION_1) {
804 			ep->clock_ref = clock_ref_find(chip, fp->clock);
805 			if (!ep->clock_ref) {
806 				ep = NULL;
807 				goto unlock;
808 			}
809 			ep->clock_ref->opened++;
810 		}
811 
812 		ep->cur_audiofmt = fp;
813 		ep->cur_channels = fp->channels;
814 		ep->cur_rate = params_rate(params);
815 		ep->cur_format = params_format(params);
816 		ep->cur_frame_bytes = snd_pcm_format_physical_width(ep->cur_format) *
817 			ep->cur_channels / 8;
818 		ep->cur_period_frames = params_period_size(params);
819 		ep->cur_period_bytes = ep->cur_period_frames * ep->cur_frame_bytes;
820 		ep->cur_buffer_periods = params_periods(params);
821 
822 		if (ep->type == SND_USB_ENDPOINT_TYPE_SYNC)
823 			endpoint_set_syncinterval(chip, ep);
824 
825 		ep->implicit_fb_sync = fp->implicit_fb;
826 		ep->need_setup = true;
827 		ep->need_prepare = true;
828 
829 		usb_audio_dbg(chip, "  channels=%d, rate=%d, format=%s, period_bytes=%d, periods=%d, implicit_fb=%d\n",
830 			      ep->cur_channels, ep->cur_rate,
831 			      snd_pcm_format_name(ep->cur_format),
832 			      ep->cur_period_bytes, ep->cur_buffer_periods,
833 			      ep->implicit_fb_sync);
834 
835 	} else {
836 		if (WARN_ON(!ep->iface_ref)) {
837 			ep = NULL;
838 			goto unlock;
839 		}
840 
841 		if (!endpoint_compatible(ep, fp, params)) {
842 			usb_audio_err(chip, "Incompatible EP setup for 0x%x\n",
843 				      ep_num);
844 			ep = NULL;
845 			goto unlock;
846 		}
847 
848 		usb_audio_dbg(chip, "Reopened EP 0x%x (count %d)\n",
849 			      ep_num, ep->opened);
850 	}
851 
852 	if (!ep->iface_ref->opened++)
853 		ep->iface_ref->need_setup = true;
854 
855 	ep->opened++;
856 
857  unlock:
858 	mutex_unlock(&chip->mutex);
859 	return ep;
860 }
861 
862 /*
863  * snd_usb_endpoint_set_sync: Link data and sync endpoints
864  *
865  * Pass NULL to sync_ep to unlink again
866  */
867 void snd_usb_endpoint_set_sync(struct snd_usb_audio *chip,
868 			       struct snd_usb_endpoint *data_ep,
869 			       struct snd_usb_endpoint *sync_ep)
870 {
871 	data_ep->sync_source = sync_ep;
872 }
873 
874 /*
875  * Set data endpoint callbacks and the assigned data stream
876  *
877  * Called at PCM trigger and cleanups.
878  * Pass NULL to deactivate each callback.
879  */
880 void snd_usb_endpoint_set_callback(struct snd_usb_endpoint *ep,
881 				   int (*prepare)(struct snd_usb_substream *subs,
882 						  struct urb *urb,
883 						  bool in_stream_lock),
884 				   void (*retire)(struct snd_usb_substream *subs,
885 						  struct urb *urb),
886 				   struct snd_usb_substream *data_subs)
887 {
888 	ep->prepare_data_urb = prepare;
889 	ep->retire_data_urb = retire;
890 	if (data_subs)
891 		ep->lowlatency_playback = data_subs->lowlatency_playback;
892 	else
893 		ep->lowlatency_playback = false;
894 	WRITE_ONCE(ep->data_subs, data_subs);
895 }
896 
897 static int endpoint_set_interface(struct snd_usb_audio *chip,
898 				  struct snd_usb_endpoint *ep,
899 				  bool set)
900 {
901 	int altset = set ? ep->altsetting : 0;
902 	int err;
903 
904 	if (ep->iface_ref->altset == altset)
905 		return 0;
906 
907 	usb_audio_dbg(chip, "Setting usb interface %d:%d for EP 0x%x\n",
908 		      ep->iface, altset, ep->ep_num);
909 	err = usb_set_interface(chip->dev, ep->iface, altset);
910 	if (err < 0) {
911 		usb_audio_err(chip, "%d:%d: usb_set_interface failed (%d)\n",
912 			      ep->iface, altset, err);
913 		return err;
914 	}
915 
916 	if (chip->quirk_flags & QUIRK_FLAG_IFACE_DELAY)
917 		msleep(50);
918 	ep->iface_ref->altset = altset;
919 	return 0;
920 }
921 
922 /*
923  * snd_usb_endpoint_close: Close the endpoint
924  *
925  * Unreference the already opened endpoint via snd_usb_endpoint_open().
926  */
927 void snd_usb_endpoint_close(struct snd_usb_audio *chip,
928 			    struct snd_usb_endpoint *ep)
929 {
930 	mutex_lock(&chip->mutex);
931 	usb_audio_dbg(chip, "Closing EP 0x%x (count %d)\n",
932 		      ep->ep_num, ep->opened);
933 
934 	if (!--ep->iface_ref->opened)
935 		endpoint_set_interface(chip, ep, false);
936 
937 	if (!--ep->opened) {
938 		if (ep->clock_ref) {
939 			if (!--ep->clock_ref->opened)
940 				ep->clock_ref->rate = 0;
941 		}
942 		ep->iface = 0;
943 		ep->altsetting = 0;
944 		ep->cur_audiofmt = NULL;
945 		ep->cur_rate = 0;
946 		ep->iface_ref = NULL;
947 		ep->clock_ref = NULL;
948 		usb_audio_dbg(chip, "EP 0x%x closed\n", ep->ep_num);
949 	}
950 	mutex_unlock(&chip->mutex);
951 }
952 
953 /* Prepare for suspening EP, called from the main suspend handler */
954 void snd_usb_endpoint_suspend(struct snd_usb_endpoint *ep)
955 {
956 	ep->need_prepare = true;
957 	if (ep->iface_ref)
958 		ep->iface_ref->need_setup = true;
959 	if (ep->clock_ref)
960 		ep->clock_ref->rate = 0;
961 }
962 
963 /*
964  *  wait until all urbs are processed.
965  */
966 static int wait_clear_urbs(struct snd_usb_endpoint *ep)
967 {
968 	unsigned long end_time = jiffies + msecs_to_jiffies(1000);
969 	int alive;
970 
971 	if (atomic_read(&ep->state) != EP_STATE_STOPPING)
972 		return 0;
973 
974 	do {
975 		alive = atomic_read(&ep->submitted_urbs);
976 		if (!alive)
977 			break;
978 
979 		schedule_timeout_uninterruptible(1);
980 	} while (time_before(jiffies, end_time));
981 
982 	if (alive)
983 		usb_audio_err(ep->chip,
984 			"timeout: still %d active urbs on EP #%x\n",
985 			alive, ep->ep_num);
986 
987 	if (ep_state_update(ep, EP_STATE_STOPPING, EP_STATE_STOPPED)) {
988 		ep->sync_sink = NULL;
989 		snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
990 	}
991 
992 	return 0;
993 }
994 
995 /* sync the pending stop operation;
996  * this function itself doesn't trigger the stop operation
997  */
998 void snd_usb_endpoint_sync_pending_stop(struct snd_usb_endpoint *ep)
999 {
1000 	if (ep)
1001 		wait_clear_urbs(ep);
1002 }
1003 
1004 /*
1005  * Stop active urbs
1006  *
1007  * This function moves the EP to STOPPING state if it's being RUNNING.
1008  */
1009 static int stop_urbs(struct snd_usb_endpoint *ep, bool force, bool keep_pending)
1010 {
1011 	unsigned int i;
1012 	unsigned long flags;
1013 
1014 	if (!force && atomic_read(&ep->running))
1015 		return -EBUSY;
1016 
1017 	if (!ep_state_update(ep, EP_STATE_RUNNING, EP_STATE_STOPPING))
1018 		return 0;
1019 
1020 	spin_lock_irqsave(&ep->lock, flags);
1021 	INIT_LIST_HEAD(&ep->ready_playback_urbs);
1022 	ep->next_packet_head = 0;
1023 	ep->next_packet_queued = 0;
1024 	spin_unlock_irqrestore(&ep->lock, flags);
1025 
1026 	if (keep_pending)
1027 		return 0;
1028 
1029 	for (i = 0; i < ep->nurbs; i++) {
1030 		if (test_bit(i, &ep->active_mask)) {
1031 			if (!test_and_set_bit(i, &ep->unlink_mask)) {
1032 				struct urb *u = ep->urb[i].urb;
1033 				usb_unlink_urb(u);
1034 			}
1035 		}
1036 	}
1037 
1038 	return 0;
1039 }
1040 
1041 /*
1042  * release an endpoint's urbs
1043  */
1044 static int release_urbs(struct snd_usb_endpoint *ep, bool force)
1045 {
1046 	int i, err;
1047 
1048 	/* route incoming urbs to nirvana */
1049 	snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
1050 
1051 	/* stop and unlink urbs */
1052 	err = stop_urbs(ep, force, false);
1053 	if (err)
1054 		return err;
1055 
1056 	wait_clear_urbs(ep);
1057 
1058 	for (i = 0; i < ep->nurbs; i++)
1059 		release_urb_ctx(&ep->urb[i]);
1060 
1061 	usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
1062 			  ep->syncbuf, ep->sync_dma);
1063 
1064 	ep->syncbuf = NULL;
1065 	ep->nurbs = 0;
1066 	return 0;
1067 }
1068 
1069 /*
1070  * configure a data endpoint
1071  */
1072 static int data_ep_set_params(struct snd_usb_endpoint *ep)
1073 {
1074 	struct snd_usb_audio *chip = ep->chip;
1075 	unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
1076 	unsigned int max_packs_per_period, urbs_per_period, urb_packs;
1077 	unsigned int max_urbs, i;
1078 	const struct audioformat *fmt = ep->cur_audiofmt;
1079 	int frame_bits = ep->cur_frame_bytes * 8;
1080 	int tx_length_quirk = (has_tx_length_quirk(chip) &&
1081 			       usb_pipeout(ep->pipe));
1082 
1083 	usb_audio_dbg(chip, "Setting params for data EP 0x%x, pipe 0x%x\n",
1084 		      ep->ep_num, ep->pipe);
1085 
1086 	if (ep->cur_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
1087 		/*
1088 		 * When operating in DSD DOP mode, the size of a sample frame
1089 		 * in hardware differs from the actual physical format width
1090 		 * because we need to make room for the DOP markers.
1091 		 */
1092 		frame_bits += ep->cur_channels << 3;
1093 	}
1094 
1095 	ep->datainterval = fmt->datainterval;
1096 	ep->stride = frame_bits >> 3;
1097 
1098 	switch (ep->cur_format) {
1099 	case SNDRV_PCM_FORMAT_U8:
1100 		ep->silence_value = 0x80;
1101 		break;
1102 	case SNDRV_PCM_FORMAT_DSD_U8:
1103 	case SNDRV_PCM_FORMAT_DSD_U16_LE:
1104 	case SNDRV_PCM_FORMAT_DSD_U32_LE:
1105 	case SNDRV_PCM_FORMAT_DSD_U16_BE:
1106 	case SNDRV_PCM_FORMAT_DSD_U32_BE:
1107 		ep->silence_value = 0x69;
1108 		break;
1109 	default:
1110 		ep->silence_value = 0;
1111 	}
1112 
1113 	/* assume max. frequency is 50% higher than nominal */
1114 	ep->freqmax = ep->freqn + (ep->freqn >> 1);
1115 	/* Round up freqmax to nearest integer in order to calculate maximum
1116 	 * packet size, which must represent a whole number of frames.
1117 	 * This is accomplished by adding 0x0.ffff before converting the
1118 	 * Q16.16 format into integer.
1119 	 * In order to accurately calculate the maximum packet size when
1120 	 * the data interval is more than 1 (i.e. ep->datainterval > 0),
1121 	 * multiply by the data interval prior to rounding. For instance,
1122 	 * a freqmax of 41 kHz will result in a max packet size of 6 (5.125)
1123 	 * frames with a data interval of 1, but 11 (10.25) frames with a
1124 	 * data interval of 2.
1125 	 * (ep->freqmax << ep->datainterval overflows at 8.192 MHz for the
1126 	 * maximum datainterval value of 3, at USB full speed, higher for
1127 	 * USB high speed, noting that ep->freqmax is in units of
1128 	 * frames per packet in Q16.16 format.)
1129 	 */
1130 	maxsize = (((ep->freqmax << ep->datainterval) + 0xffff) >> 16) *
1131 			 (frame_bits >> 3);
1132 	if (tx_length_quirk)
1133 		maxsize += sizeof(__le32); /* Space for length descriptor */
1134 	/* but wMaxPacketSize might reduce this */
1135 	if (ep->maxpacksize && ep->maxpacksize < maxsize) {
1136 		/* whatever fits into a max. size packet */
1137 		unsigned int data_maxsize = maxsize = ep->maxpacksize;
1138 
1139 		if (tx_length_quirk)
1140 			/* Need to remove the length descriptor to calc freq */
1141 			data_maxsize -= sizeof(__le32);
1142 		ep->freqmax = (data_maxsize / (frame_bits >> 3))
1143 				<< (16 - ep->datainterval);
1144 	}
1145 
1146 	if (ep->fill_max)
1147 		ep->curpacksize = ep->maxpacksize;
1148 	else
1149 		ep->curpacksize = maxsize;
1150 
1151 	if (snd_usb_get_speed(chip->dev) != USB_SPEED_FULL) {
1152 		packs_per_ms = 8 >> ep->datainterval;
1153 		max_packs_per_urb = MAX_PACKS_HS;
1154 	} else {
1155 		packs_per_ms = 1;
1156 		max_packs_per_urb = MAX_PACKS;
1157 	}
1158 	if (ep->sync_source && !ep->implicit_fb_sync)
1159 		max_packs_per_urb = min(max_packs_per_urb,
1160 					1U << ep->sync_source->syncinterval);
1161 	max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);
1162 
1163 	/*
1164 	 * Capture endpoints need to use small URBs because there's no way
1165 	 * to tell in advance where the next period will end, and we don't
1166 	 * want the next URB to complete much after the period ends.
1167 	 *
1168 	 * Playback endpoints with implicit sync much use the same parameters
1169 	 * as their corresponding capture endpoint.
1170 	 */
1171 	if (usb_pipein(ep->pipe) || ep->implicit_fb_sync) {
1172 
1173 		urb_packs = packs_per_ms;
1174 		/*
1175 		 * Wireless devices can poll at a max rate of once per 4ms.
1176 		 * For dataintervals less than 5, increase the packet count to
1177 		 * allow the host controller to use bursting to fill in the
1178 		 * gaps.
1179 		 */
1180 		if (snd_usb_get_speed(chip->dev) == USB_SPEED_WIRELESS) {
1181 			int interval = ep->datainterval;
1182 			while (interval < 5) {
1183 				urb_packs <<= 1;
1184 				++interval;
1185 			}
1186 		}
1187 		/* make capture URBs <= 1 ms and smaller than a period */
1188 		urb_packs = min(max_packs_per_urb, urb_packs);
1189 		while (urb_packs > 1 && urb_packs * maxsize >= ep->cur_period_bytes)
1190 			urb_packs >>= 1;
1191 		ep->nurbs = MAX_URBS;
1192 
1193 	/*
1194 	 * Playback endpoints without implicit sync are adjusted so that
1195 	 * a period fits as evenly as possible in the smallest number of
1196 	 * URBs.  The total number of URBs is adjusted to the size of the
1197 	 * ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
1198 	 */
1199 	} else {
1200 		/* determine how small a packet can be */
1201 		minsize = (ep->freqn >> (16 - ep->datainterval)) *
1202 				(frame_bits >> 3);
1203 		/* with sync from device, assume it can be 12% lower */
1204 		if (ep->sync_source)
1205 			minsize -= minsize >> 3;
1206 		minsize = max(minsize, 1u);
1207 
1208 		/* how many packets will contain an entire ALSA period? */
1209 		max_packs_per_period = DIV_ROUND_UP(ep->cur_period_bytes, minsize);
1210 
1211 		/* how many URBs will contain a period? */
1212 		urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
1213 				max_packs_per_urb);
1214 		/* how many packets are needed in each URB? */
1215 		urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);
1216 
1217 		/* limit the number of frames in a single URB */
1218 		ep->max_urb_frames = DIV_ROUND_UP(ep->cur_period_frames,
1219 						  urbs_per_period);
1220 
1221 		/* try to use enough URBs to contain an entire ALSA buffer */
1222 		max_urbs = min((unsigned) MAX_URBS,
1223 				MAX_QUEUE * packs_per_ms / urb_packs);
1224 		ep->nurbs = min(max_urbs, urbs_per_period * ep->cur_buffer_periods);
1225 	}
1226 
1227 	/* allocate and initialize data urbs */
1228 	for (i = 0; i < ep->nurbs; i++) {
1229 		struct snd_urb_ctx *u = &ep->urb[i];
1230 		u->index = i;
1231 		u->ep = ep;
1232 		u->packets = urb_packs;
1233 		u->buffer_size = maxsize * u->packets;
1234 
1235 		if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
1236 			u->packets++; /* for transfer delimiter */
1237 		u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
1238 		if (!u->urb)
1239 			goto out_of_memory;
1240 
1241 		u->urb->transfer_buffer =
1242 			usb_alloc_coherent(chip->dev, u->buffer_size,
1243 					   GFP_KERNEL, &u->urb->transfer_dma);
1244 		if (!u->urb->transfer_buffer)
1245 			goto out_of_memory;
1246 		u->urb->pipe = ep->pipe;
1247 		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1248 		u->urb->interval = 1 << ep->datainterval;
1249 		u->urb->context = u;
1250 		u->urb->complete = snd_complete_urb;
1251 		INIT_LIST_HEAD(&u->ready_list);
1252 	}
1253 
1254 	return 0;
1255 
1256 out_of_memory:
1257 	release_urbs(ep, false);
1258 	return -ENOMEM;
1259 }
1260 
1261 /*
1262  * configure a sync endpoint
1263  */
1264 static int sync_ep_set_params(struct snd_usb_endpoint *ep)
1265 {
1266 	struct snd_usb_audio *chip = ep->chip;
1267 	int i;
1268 
1269 	usb_audio_dbg(chip, "Setting params for sync EP 0x%x, pipe 0x%x\n",
1270 		      ep->ep_num, ep->pipe);
1271 
1272 	ep->syncbuf = usb_alloc_coherent(chip->dev, SYNC_URBS * 4,
1273 					 GFP_KERNEL, &ep->sync_dma);
1274 	if (!ep->syncbuf)
1275 		return -ENOMEM;
1276 
1277 	ep->nurbs = SYNC_URBS;
1278 	for (i = 0; i < SYNC_URBS; i++) {
1279 		struct snd_urb_ctx *u = &ep->urb[i];
1280 		u->index = i;
1281 		u->ep = ep;
1282 		u->packets = 1;
1283 		u->urb = usb_alloc_urb(1, GFP_KERNEL);
1284 		if (!u->urb)
1285 			goto out_of_memory;
1286 		u->urb->transfer_buffer = ep->syncbuf + i * 4;
1287 		u->urb->transfer_dma = ep->sync_dma + i * 4;
1288 		u->urb->transfer_buffer_length = 4;
1289 		u->urb->pipe = ep->pipe;
1290 		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1291 		u->urb->number_of_packets = 1;
1292 		u->urb->interval = 1 << ep->syncinterval;
1293 		u->urb->context = u;
1294 		u->urb->complete = snd_complete_urb;
1295 	}
1296 
1297 	return 0;
1298 
1299 out_of_memory:
1300 	release_urbs(ep, false);
1301 	return -ENOMEM;
1302 }
1303 
1304 /* update the rate of the referred clock; return the actual rate */
1305 static int update_clock_ref_rate(struct snd_usb_audio *chip,
1306 				 struct snd_usb_endpoint *ep)
1307 {
1308 	struct snd_usb_clock_ref *clock = ep->clock_ref;
1309 	int rate = ep->cur_rate;
1310 
1311 	if (!clock || clock->rate == rate)
1312 		return rate;
1313 	if (clock->rate) {
1314 		if (atomic_read(&clock->locked))
1315 			return clock->rate;
1316 		if (clock->rate != rate) {
1317 			usb_audio_err(chip, "Mismatched sample rate %d vs %d for EP 0x%x\n",
1318 				      clock->rate, rate, ep->ep_num);
1319 			return clock->rate;
1320 		}
1321 	}
1322 	clock->rate = rate;
1323 	clock->need_setup = true;
1324 	return rate;
1325 }
1326 
1327 /*
1328  * snd_usb_endpoint_set_params: configure an snd_usb_endpoint
1329  *
1330  * It's called either from hw_params callback.
1331  * Determine the number of URBs to be used on this endpoint.
1332  * An endpoint must be configured before it can be started.
1333  * An endpoint that is already running can not be reconfigured.
1334  */
1335 int snd_usb_endpoint_set_params(struct snd_usb_audio *chip,
1336 				struct snd_usb_endpoint *ep)
1337 {
1338 	const struct audioformat *fmt = ep->cur_audiofmt;
1339 	int err = 0;
1340 
1341 	mutex_lock(&chip->mutex);
1342 	if (!ep->need_setup)
1343 		goto unlock;
1344 
1345 	/* release old buffers, if any */
1346 	err = release_urbs(ep, false);
1347 	if (err < 0)
1348 		goto unlock;
1349 
1350 	ep->datainterval = fmt->datainterval;
1351 	ep->maxpacksize = fmt->maxpacksize;
1352 	ep->fill_max = !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX);
1353 
1354 	if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL) {
1355 		ep->freqn = get_usb_full_speed_rate(ep->cur_rate);
1356 		ep->pps = 1000 >> ep->datainterval;
1357 	} else {
1358 		ep->freqn = get_usb_high_speed_rate(ep->cur_rate);
1359 		ep->pps = 8000 >> ep->datainterval;
1360 	}
1361 
1362 	ep->sample_rem = ep->cur_rate % ep->pps;
1363 	ep->packsize[0] = ep->cur_rate / ep->pps;
1364 	ep->packsize[1] = (ep->cur_rate + (ep->pps - 1)) / ep->pps;
1365 
1366 	/* calculate the frequency in 16.16 format */
1367 	ep->freqm = ep->freqn;
1368 	ep->freqshift = INT_MIN;
1369 
1370 	ep->phase = 0;
1371 
1372 	switch (ep->type) {
1373 	case  SND_USB_ENDPOINT_TYPE_DATA:
1374 		err = data_ep_set_params(ep);
1375 		break;
1376 	case  SND_USB_ENDPOINT_TYPE_SYNC:
1377 		err = sync_ep_set_params(ep);
1378 		break;
1379 	default:
1380 		err = -EINVAL;
1381 	}
1382 
1383 	usb_audio_dbg(chip, "Set up %d URBS, ret=%d\n", ep->nurbs, err);
1384 
1385 	if (err < 0)
1386 		goto unlock;
1387 
1388 	/* some unit conversions in runtime */
1389 	ep->maxframesize = ep->maxpacksize / ep->cur_frame_bytes;
1390 	ep->curframesize = ep->curpacksize / ep->cur_frame_bytes;
1391 
1392 	err = update_clock_ref_rate(chip, ep);
1393 	if (err >= 0) {
1394 		ep->need_setup = false;
1395 		err = 0;
1396 	}
1397 
1398  unlock:
1399 	mutex_unlock(&chip->mutex);
1400 	return err;
1401 }
1402 
1403 static int init_sample_rate(struct snd_usb_audio *chip,
1404 			    struct snd_usb_endpoint *ep)
1405 {
1406 	struct snd_usb_clock_ref *clock = ep->clock_ref;
1407 	int rate, err;
1408 
1409 	rate = update_clock_ref_rate(chip, ep);
1410 	if (rate < 0)
1411 		return rate;
1412 	if (clock && !clock->need_setup)
1413 		return 0;
1414 
1415 	err = snd_usb_init_sample_rate(chip, ep->cur_audiofmt, rate);
1416 	if (err < 0) {
1417 		if (clock)
1418 			clock->rate = 0; /* reset rate */
1419 		return err;
1420 	}
1421 
1422 	if (clock)
1423 		clock->need_setup = false;
1424 	return 0;
1425 }
1426 
1427 /*
1428  * snd_usb_endpoint_prepare: Prepare the endpoint
1429  *
1430  * This function sets up the EP to be fully usable state.
1431  * It's called either from prepare callback.
1432  * The function checks need_setup flag, and performs nothing unless needed,
1433  * so it's safe to call this multiple times.
1434  *
1435  * This returns zero if unchanged, 1 if the configuration has changed,
1436  * or a negative error code.
1437  */
1438 int snd_usb_endpoint_prepare(struct snd_usb_audio *chip,
1439 			     struct snd_usb_endpoint *ep)
1440 {
1441 	bool iface_first;
1442 	int err = 0;
1443 
1444 	mutex_lock(&chip->mutex);
1445 	if (WARN_ON(!ep->iface_ref))
1446 		goto unlock;
1447 	if (!ep->need_prepare)
1448 		goto unlock;
1449 
1450 	/* If the interface has been already set up, just set EP parameters */
1451 	if (!ep->iface_ref->need_setup) {
1452 		/* sample rate setup of UAC1 is per endpoint, and we need
1453 		 * to update at each EP configuration
1454 		 */
1455 		if (ep->cur_audiofmt->protocol == UAC_VERSION_1) {
1456 			err = init_sample_rate(chip, ep);
1457 			if (err < 0)
1458 				goto unlock;
1459 		}
1460 		goto done;
1461 	}
1462 
1463 	/* Need to deselect altsetting at first */
1464 	endpoint_set_interface(chip, ep, false);
1465 
1466 	/* Some UAC1 devices (e.g. Yamaha THR10) need the host interface
1467 	 * to be set up before parameter setups
1468 	 */
1469 	iface_first = ep->cur_audiofmt->protocol == UAC_VERSION_1;
1470 	/* Workaround for devices that require the interface setup at first like UAC1 */
1471 	if (chip->quirk_flags & QUIRK_FLAG_SET_IFACE_FIRST)
1472 		iface_first = true;
1473 	if (iface_first) {
1474 		err = endpoint_set_interface(chip, ep, true);
1475 		if (err < 0)
1476 			goto unlock;
1477 	}
1478 
1479 	err = snd_usb_init_pitch(chip, ep->cur_audiofmt);
1480 	if (err < 0)
1481 		goto unlock;
1482 
1483 	err = init_sample_rate(chip, ep);
1484 	if (err < 0)
1485 		goto unlock;
1486 
1487 	err = snd_usb_select_mode_quirk(chip, ep->cur_audiofmt);
1488 	if (err < 0)
1489 		goto unlock;
1490 
1491 	/* for UAC2/3, enable the interface altset here at last */
1492 	if (!iface_first) {
1493 		err = endpoint_set_interface(chip, ep, true);
1494 		if (err < 0)
1495 			goto unlock;
1496 	}
1497 
1498 	ep->iface_ref->need_setup = false;
1499 
1500  done:
1501 	ep->need_prepare = false;
1502 	err = 1;
1503 
1504 unlock:
1505 	mutex_unlock(&chip->mutex);
1506 	return err;
1507 }
1508 
1509 /* get the current rate set to the given clock by any endpoint */
1510 int snd_usb_endpoint_get_clock_rate(struct snd_usb_audio *chip, int clock)
1511 {
1512 	struct snd_usb_clock_ref *ref;
1513 	int rate = 0;
1514 
1515 	if (!clock)
1516 		return 0;
1517 	mutex_lock(&chip->mutex);
1518 	list_for_each_entry(ref, &chip->clock_ref_list, list) {
1519 		if (ref->clock == clock) {
1520 			rate = ref->rate;
1521 			break;
1522 		}
1523 	}
1524 	mutex_unlock(&chip->mutex);
1525 	return rate;
1526 }
1527 
1528 /**
1529  * snd_usb_endpoint_start: start an snd_usb_endpoint
1530  *
1531  * @ep: the endpoint to start
1532  *
1533  * A call to this function will increment the running count of the endpoint.
1534  * In case it is not already running, the URBs for this endpoint will be
1535  * submitted. Otherwise, this function does nothing.
1536  *
1537  * Must be balanced to calls of snd_usb_endpoint_stop().
1538  *
1539  * Returns an error if the URB submission failed, 0 in all other cases.
1540  */
1541 int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
1542 {
1543 	bool is_playback = usb_pipeout(ep->pipe);
1544 	int err;
1545 	unsigned int i;
1546 
1547 	if (atomic_read(&ep->chip->shutdown))
1548 		return -EBADFD;
1549 
1550 	if (ep->sync_source)
1551 		WRITE_ONCE(ep->sync_source->sync_sink, ep);
1552 
1553 	usb_audio_dbg(ep->chip, "Starting %s EP 0x%x (running %d)\n",
1554 		      ep_type_name(ep->type), ep->ep_num,
1555 		      atomic_read(&ep->running));
1556 
1557 	/* already running? */
1558 	if (atomic_inc_return(&ep->running) != 1)
1559 		return 0;
1560 
1561 	if (ep->clock_ref)
1562 		atomic_inc(&ep->clock_ref->locked);
1563 
1564 	ep->active_mask = 0;
1565 	ep->unlink_mask = 0;
1566 	ep->phase = 0;
1567 	ep->sample_accum = 0;
1568 
1569 	snd_usb_endpoint_start_quirk(ep);
1570 
1571 	/*
1572 	 * If this endpoint has a data endpoint as implicit feedback source,
1573 	 * don't start the urbs here. Instead, mark them all as available,
1574 	 * wait for the record urbs to return and queue the playback urbs
1575 	 * from that context.
1576 	 */
1577 
1578 	if (!ep_state_update(ep, EP_STATE_STOPPED, EP_STATE_RUNNING))
1579 		goto __error;
1580 
1581 	if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
1582 	    !(ep->chip->quirk_flags & QUIRK_FLAG_PLAYBACK_FIRST)) {
1583 		usb_audio_dbg(ep->chip, "No URB submission due to implicit fb sync\n");
1584 		i = 0;
1585 		goto fill_rest;
1586 	}
1587 
1588 	for (i = 0; i < ep->nurbs; i++) {
1589 		struct urb *urb = ep->urb[i].urb;
1590 
1591 		if (snd_BUG_ON(!urb))
1592 			goto __error;
1593 
1594 		if (is_playback)
1595 			err = prepare_outbound_urb(ep, urb->context, true);
1596 		else
1597 			err = prepare_inbound_urb(ep, urb->context);
1598 		if (err < 0) {
1599 			/* stop filling at applptr */
1600 			if (err == -EAGAIN)
1601 				break;
1602 			usb_audio_dbg(ep->chip,
1603 				      "EP 0x%x: failed to prepare urb: %d\n",
1604 				      ep->ep_num, err);
1605 			goto __error;
1606 		}
1607 
1608 		err = usb_submit_urb(urb, GFP_ATOMIC);
1609 		if (err < 0) {
1610 			usb_audio_err(ep->chip,
1611 				"cannot submit urb %d, error %d: %s\n",
1612 				i, err, usb_error_string(err));
1613 			goto __error;
1614 		}
1615 		set_bit(i, &ep->active_mask);
1616 		atomic_inc(&ep->submitted_urbs);
1617 	}
1618 
1619 	if (!i) {
1620 		usb_audio_dbg(ep->chip, "XRUN at starting EP 0x%x\n",
1621 			      ep->ep_num);
1622 		goto __error;
1623 	}
1624 
1625 	usb_audio_dbg(ep->chip, "%d URBs submitted for EP 0x%x\n",
1626 		      i, ep->ep_num);
1627 
1628  fill_rest:
1629 	/* put the remaining URBs to ready list */
1630 	if (is_playback) {
1631 		for (; i < ep->nurbs; i++)
1632 			push_back_to_ready_list(ep, ep->urb + i);
1633 	}
1634 
1635 	return 0;
1636 
1637 __error:
1638 	snd_usb_endpoint_stop(ep, false);
1639 	return -EPIPE;
1640 }
1641 
1642 /**
1643  * snd_usb_endpoint_stop: stop an snd_usb_endpoint
1644  *
1645  * @ep: the endpoint to stop (may be NULL)
1646  * @keep_pending: keep in-flight URBs
1647  *
1648  * A call to this function will decrement the running count of the endpoint.
1649  * In case the last user has requested the endpoint stop, the URBs will
1650  * actually be deactivated.
1651  *
1652  * Must be balanced to calls of snd_usb_endpoint_start().
1653  *
1654  * The caller needs to synchronize the pending stop operation via
1655  * snd_usb_endpoint_sync_pending_stop().
1656  */
1657 void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep, bool keep_pending)
1658 {
1659 	if (!ep)
1660 		return;
1661 
1662 	usb_audio_dbg(ep->chip, "Stopping %s EP 0x%x (running %d)\n",
1663 		      ep_type_name(ep->type), ep->ep_num,
1664 		      atomic_read(&ep->running));
1665 
1666 	if (snd_BUG_ON(!atomic_read(&ep->running)))
1667 		return;
1668 
1669 	if (!atomic_dec_return(&ep->running)) {
1670 		if (ep->sync_source)
1671 			WRITE_ONCE(ep->sync_source->sync_sink, NULL);
1672 		stop_urbs(ep, false, keep_pending);
1673 		if (ep->clock_ref)
1674 			atomic_dec(&ep->clock_ref->locked);
1675 	}
1676 }
1677 
1678 /**
1679  * snd_usb_endpoint_release: Tear down an snd_usb_endpoint
1680  *
1681  * @ep: the endpoint to release
1682  *
1683  * This function does not care for the endpoint's running count but will tear
1684  * down all the streaming URBs immediately.
1685  */
1686 void snd_usb_endpoint_release(struct snd_usb_endpoint *ep)
1687 {
1688 	release_urbs(ep, true);
1689 }
1690 
1691 /**
1692  * snd_usb_endpoint_free_all: Free the resources of an snd_usb_endpoint
1693  * @chip: The chip
1694  *
1695  * This free all endpoints and those resources
1696  */
1697 void snd_usb_endpoint_free_all(struct snd_usb_audio *chip)
1698 {
1699 	struct snd_usb_endpoint *ep, *en;
1700 	struct snd_usb_iface_ref *ip, *in;
1701 	struct snd_usb_clock_ref *cp, *cn;
1702 
1703 	list_for_each_entry_safe(ep, en, &chip->ep_list, list)
1704 		kfree(ep);
1705 
1706 	list_for_each_entry_safe(ip, in, &chip->iface_ref_list, list)
1707 		kfree(ip);
1708 
1709 	list_for_each_entry_safe(cp, cn, &chip->clock_ref_list, list)
1710 		kfree(cp);
1711 }
1712 
1713 /*
1714  * snd_usb_handle_sync_urb: parse an USB sync packet
1715  *
1716  * @ep: the endpoint to handle the packet
1717  * @sender: the sending endpoint
1718  * @urb: the received packet
1719  *
1720  * This function is called from the context of an endpoint that received
1721  * the packet and is used to let another endpoint object handle the payload.
1722  */
1723 static void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
1724 				    struct snd_usb_endpoint *sender,
1725 				    const struct urb *urb)
1726 {
1727 	int shift;
1728 	unsigned int f;
1729 	unsigned long flags;
1730 
1731 	snd_BUG_ON(ep == sender);
1732 
1733 	/*
1734 	 * In case the endpoint is operating in implicit feedback mode, prepare
1735 	 * a new outbound URB that has the same layout as the received packet
1736 	 * and add it to the list of pending urbs. queue_pending_output_urbs()
1737 	 * will take care of them later.
1738 	 */
1739 	if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
1740 	    atomic_read(&ep->running)) {
1741 
1742 		/* implicit feedback case */
1743 		int i, bytes = 0;
1744 		struct snd_urb_ctx *in_ctx;
1745 		struct snd_usb_packet_info *out_packet;
1746 
1747 		in_ctx = urb->context;
1748 
1749 		/* Count overall packet size */
1750 		for (i = 0; i < in_ctx->packets; i++)
1751 			if (urb->iso_frame_desc[i].status == 0)
1752 				bytes += urb->iso_frame_desc[i].actual_length;
1753 
1754 		/*
1755 		 * skip empty packets. At least M-Audio's Fast Track Ultra stops
1756 		 * streaming once it received a 0-byte OUT URB
1757 		 */
1758 		if (bytes == 0)
1759 			return;
1760 
1761 		spin_lock_irqsave(&ep->lock, flags);
1762 		if (ep->next_packet_queued >= ARRAY_SIZE(ep->next_packet)) {
1763 			spin_unlock_irqrestore(&ep->lock, flags);
1764 			usb_audio_err(ep->chip,
1765 				      "next package FIFO overflow EP 0x%x\n",
1766 				      ep->ep_num);
1767 			notify_xrun(ep);
1768 			return;
1769 		}
1770 
1771 		out_packet = next_packet_fifo_enqueue(ep);
1772 
1773 		/*
1774 		 * Iterate through the inbound packet and prepare the lengths
1775 		 * for the output packet. The OUT packet we are about to send
1776 		 * will have the same amount of payload bytes per stride as the
1777 		 * IN packet we just received. Since the actual size is scaled
1778 		 * by the stride, use the sender stride to calculate the length
1779 		 * in case the number of channels differ between the implicitly
1780 		 * fed-back endpoint and the synchronizing endpoint.
1781 		 */
1782 
1783 		out_packet->packets = in_ctx->packets;
1784 		for (i = 0; i < in_ctx->packets; i++) {
1785 			if (urb->iso_frame_desc[i].status == 0)
1786 				out_packet->packet_size[i] =
1787 					urb->iso_frame_desc[i].actual_length / sender->stride;
1788 			else
1789 				out_packet->packet_size[i] = 0;
1790 		}
1791 
1792 		spin_unlock_irqrestore(&ep->lock, flags);
1793 		snd_usb_queue_pending_output_urbs(ep, false);
1794 
1795 		return;
1796 	}
1797 
1798 	/*
1799 	 * process after playback sync complete
1800 	 *
1801 	 * Full speed devices report feedback values in 10.14 format as samples
1802 	 * per frame, high speed devices in 16.16 format as samples per
1803 	 * microframe.
1804 	 *
1805 	 * Because the Audio Class 1 spec was written before USB 2.0, many high
1806 	 * speed devices use a wrong interpretation, some others use an
1807 	 * entirely different format.
1808 	 *
1809 	 * Therefore, we cannot predict what format any particular device uses
1810 	 * and must detect it automatically.
1811 	 */
1812 
1813 	if (urb->iso_frame_desc[0].status != 0 ||
1814 	    urb->iso_frame_desc[0].actual_length < 3)
1815 		return;
1816 
1817 	f = le32_to_cpup(urb->transfer_buffer);
1818 	if (urb->iso_frame_desc[0].actual_length == 3)
1819 		f &= 0x00ffffff;
1820 	else
1821 		f &= 0x0fffffff;
1822 
1823 	if (f == 0)
1824 		return;
1825 
1826 	if (unlikely(sender->tenor_fb_quirk)) {
1827 		/*
1828 		 * Devices based on Tenor 8802 chipsets (TEAC UD-H01
1829 		 * and others) sometimes change the feedback value
1830 		 * by +/- 0x1.0000.
1831 		 */
1832 		if (f < ep->freqn - 0x8000)
1833 			f += 0xf000;
1834 		else if (f > ep->freqn + 0x8000)
1835 			f -= 0xf000;
1836 	} else if (unlikely(ep->freqshift == INT_MIN)) {
1837 		/*
1838 		 * The first time we see a feedback value, determine its format
1839 		 * by shifting it left or right until it matches the nominal
1840 		 * frequency value.  This assumes that the feedback does not
1841 		 * differ from the nominal value more than +50% or -25%.
1842 		 */
1843 		shift = 0;
1844 		while (f < ep->freqn - ep->freqn / 4) {
1845 			f <<= 1;
1846 			shift++;
1847 		}
1848 		while (f > ep->freqn + ep->freqn / 2) {
1849 			f >>= 1;
1850 			shift--;
1851 		}
1852 		ep->freqshift = shift;
1853 	} else if (ep->freqshift >= 0)
1854 		f <<= ep->freqshift;
1855 	else
1856 		f >>= -ep->freqshift;
1857 
1858 	if (likely(f >= ep->freqn - ep->freqn / 8 && f <= ep->freqmax)) {
1859 		/*
1860 		 * If the frequency looks valid, set it.
1861 		 * This value is referred to in prepare_playback_urb().
1862 		 */
1863 		spin_lock_irqsave(&ep->lock, flags);
1864 		ep->freqm = f;
1865 		spin_unlock_irqrestore(&ep->lock, flags);
1866 	} else {
1867 		/*
1868 		 * Out of range; maybe the shift value is wrong.
1869 		 * Reset it so that we autodetect again the next time.
1870 		 */
1871 		ep->freqshift = INT_MIN;
1872 	}
1873 }
1874 
1875