xref: /linux/sound/usb/endpoint.c (revision 5ce42b5de461c3154f61a023b191dd6b77ee66c0)
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 int 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 			break;
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 				break;
501 			}
502 
503 			if (!in_stream_lock)
504 				notify_xrun(ep);
505 			return -EPIPE;
506 		}
507 
508 		if (!atomic_read(&ep->chip->shutdown))
509 			err = usb_submit_urb(ctx->urb, GFP_ATOMIC);
510 		else
511 			err = -ENODEV;
512 		if (err < 0) {
513 			if (!atomic_read(&ep->chip->shutdown)) {
514 				usb_audio_err(ep->chip,
515 					      "Unable to submit urb #%d: %d at %s\n",
516 					      ctx->index, err, __func__);
517 				if (!in_stream_lock)
518 					notify_xrun(ep);
519 			}
520 			return -EPIPE;
521 		}
522 
523 		set_bit(ctx->index, &ep->active_mask);
524 		atomic_inc(&ep->submitted_urbs);
525 	}
526 
527 	return 0;
528 }
529 
530 /*
531  * complete callback for urbs
532  */
533 static void snd_complete_urb(struct urb *urb)
534 {
535 	struct snd_urb_ctx *ctx = urb->context;
536 	struct snd_usb_endpoint *ep = ctx->ep;
537 	int err;
538 
539 	if (unlikely(urb->status == -ENOENT ||		/* unlinked */
540 		     urb->status == -ENODEV ||		/* device removed */
541 		     urb->status == -ECONNRESET ||	/* unlinked */
542 		     urb->status == -ESHUTDOWN))	/* device disabled */
543 		goto exit_clear;
544 	/* device disconnected */
545 	if (unlikely(atomic_read(&ep->chip->shutdown)))
546 		goto exit_clear;
547 
548 	if (unlikely(!ep_state_running(ep)))
549 		goto exit_clear;
550 
551 	if (usb_pipeout(ep->pipe)) {
552 		retire_outbound_urb(ep, ctx);
553 		/* can be stopped during retire callback */
554 		if (unlikely(!ep_state_running(ep)))
555 			goto exit_clear;
556 
557 		/* in low-latency and implicit-feedback modes, push back the
558 		 * URB to ready list at first, then process as much as possible
559 		 */
560 		if (ep->lowlatency_playback ||
561 		     snd_usb_endpoint_implicit_feedback_sink(ep)) {
562 			push_back_to_ready_list(ep, ctx);
563 			clear_bit(ctx->index, &ep->active_mask);
564 			snd_usb_queue_pending_output_urbs(ep, false);
565 			atomic_dec(&ep->submitted_urbs); /* decrement at last */
566 			return;
567 		}
568 
569 		/* in non-lowlatency mode, no error handling for prepare */
570 		prepare_outbound_urb(ep, ctx, false);
571 		/* can be stopped during prepare callback */
572 		if (unlikely(!ep_state_running(ep)))
573 			goto exit_clear;
574 	} else {
575 		retire_inbound_urb(ep, ctx);
576 		/* can be stopped during retire callback */
577 		if (unlikely(!ep_state_running(ep)))
578 			goto exit_clear;
579 
580 		prepare_inbound_urb(ep, ctx);
581 	}
582 
583 	if (!atomic_read(&ep->chip->shutdown))
584 		err = usb_submit_urb(urb, GFP_ATOMIC);
585 	else
586 		err = -ENODEV;
587 	if (err == 0)
588 		return;
589 
590 	if (!atomic_read(&ep->chip->shutdown)) {
591 		usb_audio_err(ep->chip, "cannot submit urb (err = %d)\n", err);
592 		notify_xrun(ep);
593 	}
594 
595 exit_clear:
596 	clear_bit(ctx->index, &ep->active_mask);
597 	atomic_dec(&ep->submitted_urbs);
598 }
599 
600 /*
601  * Find or create a refcount object for the given interface
602  *
603  * The objects are released altogether in snd_usb_endpoint_free_all()
604  */
605 static struct snd_usb_iface_ref *
606 iface_ref_find(struct snd_usb_audio *chip, int iface)
607 {
608 	struct snd_usb_iface_ref *ip;
609 
610 	list_for_each_entry(ip, &chip->iface_ref_list, list)
611 		if (ip->iface == iface)
612 			return ip;
613 
614 	ip = kzalloc(sizeof(*ip), GFP_KERNEL);
615 	if (!ip)
616 		return NULL;
617 	ip->iface = iface;
618 	list_add_tail(&ip->list, &chip->iface_ref_list);
619 	return ip;
620 }
621 
622 /* Similarly, a refcount object for clock */
623 static struct snd_usb_clock_ref *
624 clock_ref_find(struct snd_usb_audio *chip, int clock)
625 {
626 	struct snd_usb_clock_ref *ref;
627 
628 	list_for_each_entry(ref, &chip->clock_ref_list, list)
629 		if (ref->clock == clock)
630 			return ref;
631 
632 	ref = kzalloc(sizeof(*ref), GFP_KERNEL);
633 	if (!ref)
634 		return NULL;
635 	ref->clock = clock;
636 	atomic_set(&ref->locked, 0);
637 	list_add_tail(&ref->list, &chip->clock_ref_list);
638 	return ref;
639 }
640 
641 /*
642  * Get the existing endpoint object corresponding EP
643  * Returns NULL if not present.
644  */
645 struct snd_usb_endpoint *
646 snd_usb_get_endpoint(struct snd_usb_audio *chip, int ep_num)
647 {
648 	struct snd_usb_endpoint *ep;
649 
650 	list_for_each_entry(ep, &chip->ep_list, list) {
651 		if (ep->ep_num == ep_num)
652 			return ep;
653 	}
654 
655 	return NULL;
656 }
657 
658 #define ep_type_name(type) \
659 	(type == SND_USB_ENDPOINT_TYPE_DATA ? "data" : "sync")
660 
661 /**
662  * snd_usb_add_endpoint: Add an endpoint to an USB audio chip
663  *
664  * @chip: The chip
665  * @ep_num: The number of the endpoint to use
666  * @type: SND_USB_ENDPOINT_TYPE_DATA or SND_USB_ENDPOINT_TYPE_SYNC
667  *
668  * If the requested endpoint has not been added to the given chip before,
669  * a new instance is created.
670  *
671  * Returns zero on success or a negative error code.
672  *
673  * New endpoints will be added to chip->ep_list and freed by
674  * calling snd_usb_endpoint_free_all().
675  *
676  * For SND_USB_ENDPOINT_TYPE_SYNC, the caller needs to guarantee that
677  * bNumEndpoints > 1 beforehand.
678  */
679 int snd_usb_add_endpoint(struct snd_usb_audio *chip, int ep_num, int type)
680 {
681 	struct snd_usb_endpoint *ep;
682 	bool is_playback;
683 
684 	ep = snd_usb_get_endpoint(chip, ep_num);
685 	if (ep)
686 		return 0;
687 
688 	usb_audio_dbg(chip, "Creating new %s endpoint #%x\n",
689 		      ep_type_name(type),
690 		      ep_num);
691 	ep = kzalloc(sizeof(*ep), GFP_KERNEL);
692 	if (!ep)
693 		return -ENOMEM;
694 
695 	ep->chip = chip;
696 	spin_lock_init(&ep->lock);
697 	ep->type = type;
698 	ep->ep_num = ep_num;
699 	INIT_LIST_HEAD(&ep->ready_playback_urbs);
700 	atomic_set(&ep->submitted_urbs, 0);
701 
702 	is_playback = ((ep_num & USB_ENDPOINT_DIR_MASK) == USB_DIR_OUT);
703 	ep_num &= USB_ENDPOINT_NUMBER_MASK;
704 	if (is_playback)
705 		ep->pipe = usb_sndisocpipe(chip->dev, ep_num);
706 	else
707 		ep->pipe = usb_rcvisocpipe(chip->dev, ep_num);
708 
709 	list_add_tail(&ep->list, &chip->ep_list);
710 	return 0;
711 }
712 
713 /* Set up syncinterval and maxsyncsize for a sync EP */
714 static void endpoint_set_syncinterval(struct snd_usb_audio *chip,
715 				      struct snd_usb_endpoint *ep)
716 {
717 	struct usb_host_interface *alts;
718 	struct usb_endpoint_descriptor *desc;
719 
720 	alts = snd_usb_get_host_interface(chip, ep->iface, ep->altsetting);
721 	if (!alts)
722 		return;
723 
724 	desc = get_endpoint(alts, ep->ep_idx);
725 	if (desc->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
726 	    desc->bRefresh >= 1 && desc->bRefresh <= 9)
727 		ep->syncinterval = desc->bRefresh;
728 	else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL)
729 		ep->syncinterval = 1;
730 	else if (desc->bInterval >= 1 && desc->bInterval <= 16)
731 		ep->syncinterval = desc->bInterval - 1;
732 	else
733 		ep->syncinterval = 3;
734 
735 	ep->syncmaxsize = le16_to_cpu(desc->wMaxPacketSize);
736 }
737 
738 static bool endpoint_compatible(struct snd_usb_endpoint *ep,
739 				const struct audioformat *fp,
740 				const struct snd_pcm_hw_params *params)
741 {
742 	if (!ep->opened)
743 		return false;
744 	if (ep->cur_audiofmt != fp)
745 		return false;
746 	if (ep->cur_rate != params_rate(params) ||
747 	    ep->cur_format != params_format(params) ||
748 	    ep->cur_period_frames != params_period_size(params) ||
749 	    ep->cur_buffer_periods != params_periods(params))
750 		return false;
751 	return true;
752 }
753 
754 /*
755  * Check whether the given fp and hw params are compatible with the current
756  * setup of the target EP for implicit feedback sync
757  */
758 bool snd_usb_endpoint_compatible(struct snd_usb_audio *chip,
759 				 struct snd_usb_endpoint *ep,
760 				 const struct audioformat *fp,
761 				 const struct snd_pcm_hw_params *params)
762 {
763 	bool ret;
764 
765 	mutex_lock(&chip->mutex);
766 	ret = endpoint_compatible(ep, fp, params);
767 	mutex_unlock(&chip->mutex);
768 	return ret;
769 }
770 
771 /*
772  * snd_usb_endpoint_open: Open the endpoint
773  *
774  * Called from hw_params to assign the endpoint to the substream.
775  * It's reference-counted, and only the first opener is allowed to set up
776  * arbitrary parameters.  The later opener must be compatible with the
777  * former opened parameters.
778  * The endpoint needs to be closed via snd_usb_endpoint_close() later.
779  *
780  * Note that this function doesn't configure the endpoint.  The substream
781  * needs to set it up later via snd_usb_endpoint_set_params() and
782  * snd_usb_endpoint_prepare().
783  */
784 struct snd_usb_endpoint *
785 snd_usb_endpoint_open(struct snd_usb_audio *chip,
786 		      const struct audioformat *fp,
787 		      const struct snd_pcm_hw_params *params,
788 		      bool is_sync_ep,
789 		      bool fixed_rate)
790 {
791 	struct snd_usb_endpoint *ep;
792 	int ep_num = is_sync_ep ? fp->sync_ep : fp->endpoint;
793 
794 	mutex_lock(&chip->mutex);
795 	ep = snd_usb_get_endpoint(chip, ep_num);
796 	if (!ep) {
797 		usb_audio_err(chip, "Cannot find EP 0x%x to open\n", ep_num);
798 		goto unlock;
799 	}
800 
801 	if (!ep->opened) {
802 		if (is_sync_ep) {
803 			ep->iface = fp->sync_iface;
804 			ep->altsetting = fp->sync_altsetting;
805 			ep->ep_idx = fp->sync_ep_idx;
806 		} else {
807 			ep->iface = fp->iface;
808 			ep->altsetting = fp->altsetting;
809 			ep->ep_idx = fp->ep_idx;
810 		}
811 		usb_audio_dbg(chip, "Open EP 0x%x, iface=%d:%d, idx=%d\n",
812 			      ep_num, ep->iface, ep->altsetting, ep->ep_idx);
813 
814 		ep->iface_ref = iface_ref_find(chip, ep->iface);
815 		if (!ep->iface_ref) {
816 			ep = NULL;
817 			goto unlock;
818 		}
819 
820 		if (fp->protocol != UAC_VERSION_1) {
821 			ep->clock_ref = clock_ref_find(chip, fp->clock);
822 			if (!ep->clock_ref) {
823 				ep = NULL;
824 				goto unlock;
825 			}
826 			ep->clock_ref->opened++;
827 		}
828 
829 		ep->cur_audiofmt = fp;
830 		ep->cur_channels = fp->channels;
831 		ep->cur_rate = params_rate(params);
832 		ep->cur_format = params_format(params);
833 		ep->cur_frame_bytes = snd_pcm_format_physical_width(ep->cur_format) *
834 			ep->cur_channels / 8;
835 		ep->cur_period_frames = params_period_size(params);
836 		ep->cur_period_bytes = ep->cur_period_frames * ep->cur_frame_bytes;
837 		ep->cur_buffer_periods = params_periods(params);
838 
839 		if (ep->type == SND_USB_ENDPOINT_TYPE_SYNC)
840 			endpoint_set_syncinterval(chip, ep);
841 
842 		ep->implicit_fb_sync = fp->implicit_fb;
843 		ep->need_setup = true;
844 		ep->need_prepare = true;
845 		ep->fixed_rate = fixed_rate;
846 
847 		usb_audio_dbg(chip, "  channels=%d, rate=%d, format=%s, period_bytes=%d, periods=%d, implicit_fb=%d\n",
848 			      ep->cur_channels, ep->cur_rate,
849 			      snd_pcm_format_name(ep->cur_format),
850 			      ep->cur_period_bytes, ep->cur_buffer_periods,
851 			      ep->implicit_fb_sync);
852 
853 	} else {
854 		if (WARN_ON(!ep->iface_ref)) {
855 			ep = NULL;
856 			goto unlock;
857 		}
858 
859 		if (!endpoint_compatible(ep, fp, params)) {
860 			usb_audio_err(chip, "Incompatible EP setup for 0x%x\n",
861 				      ep_num);
862 			ep = NULL;
863 			goto unlock;
864 		}
865 
866 		usb_audio_dbg(chip, "Reopened EP 0x%x (count %d)\n",
867 			      ep_num, ep->opened);
868 	}
869 
870 	if (!ep->iface_ref->opened++)
871 		ep->iface_ref->need_setup = true;
872 
873 	ep->opened++;
874 
875  unlock:
876 	mutex_unlock(&chip->mutex);
877 	return ep;
878 }
879 
880 /*
881  * snd_usb_endpoint_set_sync: Link data and sync endpoints
882  *
883  * Pass NULL to sync_ep to unlink again
884  */
885 void snd_usb_endpoint_set_sync(struct snd_usb_audio *chip,
886 			       struct snd_usb_endpoint *data_ep,
887 			       struct snd_usb_endpoint *sync_ep)
888 {
889 	data_ep->sync_source = sync_ep;
890 }
891 
892 /*
893  * Set data endpoint callbacks and the assigned data stream
894  *
895  * Called at PCM trigger and cleanups.
896  * Pass NULL to deactivate each callback.
897  */
898 void snd_usb_endpoint_set_callback(struct snd_usb_endpoint *ep,
899 				   int (*prepare)(struct snd_usb_substream *subs,
900 						  struct urb *urb,
901 						  bool in_stream_lock),
902 				   void (*retire)(struct snd_usb_substream *subs,
903 						  struct urb *urb),
904 				   struct snd_usb_substream *data_subs)
905 {
906 	ep->prepare_data_urb = prepare;
907 	ep->retire_data_urb = retire;
908 	if (data_subs)
909 		ep->lowlatency_playback = data_subs->lowlatency_playback;
910 	else
911 		ep->lowlatency_playback = false;
912 	WRITE_ONCE(ep->data_subs, data_subs);
913 }
914 
915 static int endpoint_set_interface(struct snd_usb_audio *chip,
916 				  struct snd_usb_endpoint *ep,
917 				  bool set)
918 {
919 	int altset = set ? ep->altsetting : 0;
920 	int err;
921 
922 	if (ep->iface_ref->altset == altset)
923 		return 0;
924 	/* already disconnected? */
925 	if (unlikely(atomic_read(&chip->shutdown)))
926 		return -ENODEV;
927 
928 	usb_audio_dbg(chip, "Setting usb interface %d:%d for EP 0x%x\n",
929 		      ep->iface, altset, ep->ep_num);
930 	err = usb_set_interface(chip->dev, ep->iface, altset);
931 	if (err < 0) {
932 		usb_audio_err_ratelimited(
933 			chip, "%d:%d: usb_set_interface failed (%d)\n",
934 			ep->iface, altset, err);
935 		return err;
936 	}
937 
938 	if (chip->quirk_flags & QUIRK_FLAG_IFACE_DELAY)
939 		msleep(50);
940 	ep->iface_ref->altset = altset;
941 	return 0;
942 }
943 
944 /*
945  * snd_usb_endpoint_close: Close the endpoint
946  *
947  * Unreference the already opened endpoint via snd_usb_endpoint_open().
948  */
949 void snd_usb_endpoint_close(struct snd_usb_audio *chip,
950 			    struct snd_usb_endpoint *ep)
951 {
952 	mutex_lock(&chip->mutex);
953 	usb_audio_dbg(chip, "Closing EP 0x%x (count %d)\n",
954 		      ep->ep_num, ep->opened);
955 
956 	if (!--ep->iface_ref->opened &&
957 		!(chip->quirk_flags & QUIRK_FLAG_IFACE_SKIP_CLOSE))
958 		endpoint_set_interface(chip, ep, false);
959 
960 	if (!--ep->opened) {
961 		if (ep->clock_ref) {
962 			if (!--ep->clock_ref->opened)
963 				ep->clock_ref->rate = 0;
964 		}
965 		ep->iface = 0;
966 		ep->altsetting = 0;
967 		ep->cur_audiofmt = NULL;
968 		ep->cur_rate = 0;
969 		ep->iface_ref = NULL;
970 		ep->clock_ref = NULL;
971 		usb_audio_dbg(chip, "EP 0x%x closed\n", ep->ep_num);
972 	}
973 	mutex_unlock(&chip->mutex);
974 }
975 
976 /* Prepare for suspening EP, called from the main suspend handler */
977 void snd_usb_endpoint_suspend(struct snd_usb_endpoint *ep)
978 {
979 	ep->need_prepare = true;
980 	if (ep->iface_ref)
981 		ep->iface_ref->need_setup = true;
982 	if (ep->clock_ref)
983 		ep->clock_ref->rate = 0;
984 }
985 
986 /*
987  *  wait until all urbs are processed.
988  */
989 static int wait_clear_urbs(struct snd_usb_endpoint *ep)
990 {
991 	unsigned long end_time = jiffies + msecs_to_jiffies(1000);
992 	int alive;
993 
994 	if (atomic_read(&ep->state) != EP_STATE_STOPPING)
995 		return 0;
996 
997 	do {
998 		alive = atomic_read(&ep->submitted_urbs);
999 		if (!alive)
1000 			break;
1001 
1002 		schedule_timeout_uninterruptible(1);
1003 	} while (time_before(jiffies, end_time));
1004 
1005 	if (alive)
1006 		usb_audio_err(ep->chip,
1007 			"timeout: still %d active urbs on EP #%x\n",
1008 			alive, ep->ep_num);
1009 
1010 	if (ep_state_update(ep, EP_STATE_STOPPING, EP_STATE_STOPPED)) {
1011 		ep->sync_sink = NULL;
1012 		snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
1013 	}
1014 
1015 	return 0;
1016 }
1017 
1018 /* sync the pending stop operation;
1019  * this function itself doesn't trigger the stop operation
1020  */
1021 void snd_usb_endpoint_sync_pending_stop(struct snd_usb_endpoint *ep)
1022 {
1023 	if (ep)
1024 		wait_clear_urbs(ep);
1025 }
1026 
1027 /*
1028  * Stop active urbs
1029  *
1030  * This function moves the EP to STOPPING state if it's being RUNNING.
1031  */
1032 static int stop_urbs(struct snd_usb_endpoint *ep, bool force, bool keep_pending)
1033 {
1034 	unsigned int i;
1035 	unsigned long flags;
1036 
1037 	if (!force && atomic_read(&ep->running))
1038 		return -EBUSY;
1039 
1040 	if (!ep_state_update(ep, EP_STATE_RUNNING, EP_STATE_STOPPING))
1041 		return 0;
1042 
1043 	spin_lock_irqsave(&ep->lock, flags);
1044 	INIT_LIST_HEAD(&ep->ready_playback_urbs);
1045 	ep->next_packet_head = 0;
1046 	ep->next_packet_queued = 0;
1047 	spin_unlock_irqrestore(&ep->lock, flags);
1048 
1049 	if (keep_pending)
1050 		return 0;
1051 
1052 	for (i = 0; i < ep->nurbs; i++) {
1053 		if (test_bit(i, &ep->active_mask)) {
1054 			if (!test_and_set_bit(i, &ep->unlink_mask)) {
1055 				struct urb *u = ep->urb[i].urb;
1056 				usb_unlink_urb(u);
1057 			}
1058 		}
1059 	}
1060 
1061 	return 0;
1062 }
1063 
1064 /*
1065  * release an endpoint's urbs
1066  */
1067 static int release_urbs(struct snd_usb_endpoint *ep, bool force)
1068 {
1069 	int i, err;
1070 
1071 	/* route incoming urbs to nirvana */
1072 	snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
1073 
1074 	/* stop and unlink urbs */
1075 	err = stop_urbs(ep, force, false);
1076 	if (err)
1077 		return err;
1078 
1079 	wait_clear_urbs(ep);
1080 
1081 	for (i = 0; i < ep->nurbs; i++)
1082 		release_urb_ctx(&ep->urb[i]);
1083 
1084 	usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
1085 			  ep->syncbuf, ep->sync_dma);
1086 
1087 	ep->syncbuf = NULL;
1088 	ep->nurbs = 0;
1089 	return 0;
1090 }
1091 
1092 /*
1093  * configure a data endpoint
1094  */
1095 static int data_ep_set_params(struct snd_usb_endpoint *ep)
1096 {
1097 	struct snd_usb_audio *chip = ep->chip;
1098 	unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
1099 	unsigned int max_packs_per_period, urbs_per_period, urb_packs;
1100 	unsigned int max_urbs, i;
1101 	const struct audioformat *fmt = ep->cur_audiofmt;
1102 	int frame_bits = ep->cur_frame_bytes * 8;
1103 	int tx_length_quirk = (has_tx_length_quirk(chip) &&
1104 			       usb_pipeout(ep->pipe));
1105 
1106 	usb_audio_dbg(chip, "Setting params for data EP 0x%x, pipe 0x%x\n",
1107 		      ep->ep_num, ep->pipe);
1108 
1109 	if (ep->cur_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
1110 		/*
1111 		 * When operating in DSD DOP mode, the size of a sample frame
1112 		 * in hardware differs from the actual physical format width
1113 		 * because we need to make room for the DOP markers.
1114 		 */
1115 		frame_bits += ep->cur_channels << 3;
1116 	}
1117 
1118 	ep->datainterval = fmt->datainterval;
1119 	ep->stride = frame_bits >> 3;
1120 
1121 	switch (ep->cur_format) {
1122 	case SNDRV_PCM_FORMAT_U8:
1123 		ep->silence_value = 0x80;
1124 		break;
1125 	case SNDRV_PCM_FORMAT_DSD_U8:
1126 	case SNDRV_PCM_FORMAT_DSD_U16_LE:
1127 	case SNDRV_PCM_FORMAT_DSD_U32_LE:
1128 	case SNDRV_PCM_FORMAT_DSD_U16_BE:
1129 	case SNDRV_PCM_FORMAT_DSD_U32_BE:
1130 		ep->silence_value = 0x69;
1131 		break;
1132 	default:
1133 		ep->silence_value = 0;
1134 	}
1135 
1136 	/* assume max. frequency is 50% higher than nominal */
1137 	ep->freqmax = ep->freqn + (ep->freqn >> 1);
1138 	/* Round up freqmax to nearest integer in order to calculate maximum
1139 	 * packet size, which must represent a whole number of frames.
1140 	 * This is accomplished by adding 0x0.ffff before converting the
1141 	 * Q16.16 format into integer.
1142 	 * In order to accurately calculate the maximum packet size when
1143 	 * the data interval is more than 1 (i.e. ep->datainterval > 0),
1144 	 * multiply by the data interval prior to rounding. For instance,
1145 	 * a freqmax of 41 kHz will result in a max packet size of 6 (5.125)
1146 	 * frames with a data interval of 1, but 11 (10.25) frames with a
1147 	 * data interval of 2.
1148 	 * (ep->freqmax << ep->datainterval overflows at 8.192 MHz for the
1149 	 * maximum datainterval value of 3, at USB full speed, higher for
1150 	 * USB high speed, noting that ep->freqmax is in units of
1151 	 * frames per packet in Q16.16 format.)
1152 	 */
1153 	maxsize = (((ep->freqmax << ep->datainterval) + 0xffff) >> 16) *
1154 			 (frame_bits >> 3);
1155 	if (tx_length_quirk)
1156 		maxsize += sizeof(__le32); /* Space for length descriptor */
1157 	/* but wMaxPacketSize might reduce this */
1158 	if (ep->maxpacksize && ep->maxpacksize < maxsize) {
1159 		/* whatever fits into a max. size packet */
1160 		unsigned int data_maxsize = maxsize = ep->maxpacksize;
1161 
1162 		if (tx_length_quirk)
1163 			/* Need to remove the length descriptor to calc freq */
1164 			data_maxsize -= sizeof(__le32);
1165 		ep->freqmax = (data_maxsize / (frame_bits >> 3))
1166 				<< (16 - ep->datainterval);
1167 	}
1168 
1169 	if (ep->fill_max)
1170 		ep->curpacksize = ep->maxpacksize;
1171 	else
1172 		ep->curpacksize = maxsize;
1173 
1174 	if (snd_usb_get_speed(chip->dev) != USB_SPEED_FULL) {
1175 		packs_per_ms = 8 >> ep->datainterval;
1176 		max_packs_per_urb = MAX_PACKS_HS;
1177 	} else {
1178 		packs_per_ms = 1;
1179 		max_packs_per_urb = MAX_PACKS;
1180 	}
1181 	if (ep->sync_source && !ep->implicit_fb_sync)
1182 		max_packs_per_urb = min(max_packs_per_urb,
1183 					1U << ep->sync_source->syncinterval);
1184 	max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);
1185 
1186 	/*
1187 	 * Capture endpoints need to use small URBs because there's no way
1188 	 * to tell in advance where the next period will end, and we don't
1189 	 * want the next URB to complete much after the period ends.
1190 	 *
1191 	 * Playback endpoints with implicit sync much use the same parameters
1192 	 * as their corresponding capture endpoint.
1193 	 */
1194 	if (usb_pipein(ep->pipe) || ep->implicit_fb_sync) {
1195 
1196 		/* make capture URBs <= 1 ms and smaller than a period */
1197 		urb_packs = min(max_packs_per_urb, packs_per_ms);
1198 		while (urb_packs > 1 && urb_packs * maxsize >= ep->cur_period_bytes)
1199 			urb_packs >>= 1;
1200 		ep->nurbs = MAX_URBS;
1201 
1202 	/*
1203 	 * Playback endpoints without implicit sync are adjusted so that
1204 	 * a period fits as evenly as possible in the smallest number of
1205 	 * URBs.  The total number of URBs is adjusted to the size of the
1206 	 * ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
1207 	 */
1208 	} else {
1209 		/* determine how small a packet can be */
1210 		minsize = (ep->freqn >> (16 - ep->datainterval)) *
1211 				(frame_bits >> 3);
1212 		/* with sync from device, assume it can be 12% lower */
1213 		if (ep->sync_source)
1214 			minsize -= minsize >> 3;
1215 		minsize = max(minsize, 1u);
1216 
1217 		/* how many packets will contain an entire ALSA period? */
1218 		max_packs_per_period = DIV_ROUND_UP(ep->cur_period_bytes, minsize);
1219 
1220 		/* how many URBs will contain a period? */
1221 		urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
1222 				max_packs_per_urb);
1223 		/* how many packets are needed in each URB? */
1224 		urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);
1225 
1226 		/* limit the number of frames in a single URB */
1227 		ep->max_urb_frames = DIV_ROUND_UP(ep->cur_period_frames,
1228 						  urbs_per_period);
1229 
1230 		/* try to use enough URBs to contain an entire ALSA buffer */
1231 		max_urbs = min((unsigned) MAX_URBS,
1232 				MAX_QUEUE * packs_per_ms / urb_packs);
1233 		ep->nurbs = min(max_urbs, urbs_per_period * ep->cur_buffer_periods);
1234 	}
1235 
1236 	/* allocate and initialize data urbs */
1237 	for (i = 0; i < ep->nurbs; i++) {
1238 		struct snd_urb_ctx *u = &ep->urb[i];
1239 		u->index = i;
1240 		u->ep = ep;
1241 		u->packets = urb_packs;
1242 		u->buffer_size = maxsize * u->packets;
1243 
1244 		if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
1245 			u->packets++; /* for transfer delimiter */
1246 		u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
1247 		if (!u->urb)
1248 			goto out_of_memory;
1249 
1250 		u->urb->transfer_buffer =
1251 			usb_alloc_coherent(chip->dev, u->buffer_size,
1252 					   GFP_KERNEL, &u->urb->transfer_dma);
1253 		if (!u->urb->transfer_buffer)
1254 			goto out_of_memory;
1255 		u->urb->pipe = ep->pipe;
1256 		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1257 		u->urb->interval = 1 << ep->datainterval;
1258 		u->urb->context = u;
1259 		u->urb->complete = snd_complete_urb;
1260 		INIT_LIST_HEAD(&u->ready_list);
1261 	}
1262 
1263 	return 0;
1264 
1265 out_of_memory:
1266 	release_urbs(ep, false);
1267 	return -ENOMEM;
1268 }
1269 
1270 /*
1271  * configure a sync endpoint
1272  */
1273 static int sync_ep_set_params(struct snd_usb_endpoint *ep)
1274 {
1275 	struct snd_usb_audio *chip = ep->chip;
1276 	int i;
1277 
1278 	usb_audio_dbg(chip, "Setting params for sync EP 0x%x, pipe 0x%x\n",
1279 		      ep->ep_num, ep->pipe);
1280 
1281 	ep->syncbuf = usb_alloc_coherent(chip->dev, SYNC_URBS * 4,
1282 					 GFP_KERNEL, &ep->sync_dma);
1283 	if (!ep->syncbuf)
1284 		return -ENOMEM;
1285 
1286 	ep->nurbs = SYNC_URBS;
1287 	for (i = 0; i < SYNC_URBS; i++) {
1288 		struct snd_urb_ctx *u = &ep->urb[i];
1289 		u->index = i;
1290 		u->ep = ep;
1291 		u->packets = 1;
1292 		u->urb = usb_alloc_urb(1, GFP_KERNEL);
1293 		if (!u->urb)
1294 			goto out_of_memory;
1295 		u->urb->transfer_buffer = ep->syncbuf + i * 4;
1296 		u->urb->transfer_dma = ep->sync_dma + i * 4;
1297 		u->urb->transfer_buffer_length = 4;
1298 		u->urb->pipe = ep->pipe;
1299 		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
1300 		u->urb->number_of_packets = 1;
1301 		u->urb->interval = 1 << ep->syncinterval;
1302 		u->urb->context = u;
1303 		u->urb->complete = snd_complete_urb;
1304 	}
1305 
1306 	return 0;
1307 
1308 out_of_memory:
1309 	release_urbs(ep, false);
1310 	return -ENOMEM;
1311 }
1312 
1313 /* update the rate of the referred clock; return the actual rate */
1314 static int update_clock_ref_rate(struct snd_usb_audio *chip,
1315 				 struct snd_usb_endpoint *ep)
1316 {
1317 	struct snd_usb_clock_ref *clock = ep->clock_ref;
1318 	int rate = ep->cur_rate;
1319 
1320 	if (!clock || clock->rate == rate)
1321 		return rate;
1322 	if (clock->rate) {
1323 		if (atomic_read(&clock->locked))
1324 			return clock->rate;
1325 		if (clock->rate != rate) {
1326 			usb_audio_err(chip, "Mismatched sample rate %d vs %d for EP 0x%x\n",
1327 				      clock->rate, rate, ep->ep_num);
1328 			return clock->rate;
1329 		}
1330 	}
1331 	clock->rate = rate;
1332 	clock->need_setup = true;
1333 	return rate;
1334 }
1335 
1336 /*
1337  * snd_usb_endpoint_set_params: configure an snd_usb_endpoint
1338  *
1339  * It's called either from hw_params callback.
1340  * Determine the number of URBs to be used on this endpoint.
1341  * An endpoint must be configured before it can be started.
1342  * An endpoint that is already running can not be reconfigured.
1343  */
1344 int snd_usb_endpoint_set_params(struct snd_usb_audio *chip,
1345 				struct snd_usb_endpoint *ep)
1346 {
1347 	const struct audioformat *fmt = ep->cur_audiofmt;
1348 	int err = 0;
1349 
1350 	mutex_lock(&chip->mutex);
1351 	if (!ep->need_setup)
1352 		goto unlock;
1353 
1354 	/* release old buffers, if any */
1355 	err = release_urbs(ep, false);
1356 	if (err < 0)
1357 		goto unlock;
1358 
1359 	ep->datainterval = fmt->datainterval;
1360 	ep->maxpacksize = fmt->maxpacksize;
1361 	ep->fill_max = !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX);
1362 
1363 	if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL) {
1364 		ep->freqn = get_usb_full_speed_rate(ep->cur_rate);
1365 		ep->pps = 1000 >> ep->datainterval;
1366 	} else {
1367 		ep->freqn = get_usb_high_speed_rate(ep->cur_rate);
1368 		ep->pps = 8000 >> ep->datainterval;
1369 	}
1370 
1371 	ep->sample_rem = ep->cur_rate % ep->pps;
1372 	ep->packsize[0] = ep->cur_rate / ep->pps;
1373 	ep->packsize[1] = (ep->cur_rate + (ep->pps - 1)) / ep->pps;
1374 
1375 	/* calculate the frequency in 16.16 format */
1376 	ep->freqm = ep->freqn;
1377 	ep->freqshift = INT_MIN;
1378 
1379 	ep->phase = 0;
1380 
1381 	switch (ep->type) {
1382 	case  SND_USB_ENDPOINT_TYPE_DATA:
1383 		err = data_ep_set_params(ep);
1384 		break;
1385 	case  SND_USB_ENDPOINT_TYPE_SYNC:
1386 		err = sync_ep_set_params(ep);
1387 		break;
1388 	default:
1389 		err = -EINVAL;
1390 	}
1391 
1392 	usb_audio_dbg(chip, "Set up %d URBS, ret=%d\n", ep->nurbs, err);
1393 
1394 	if (err < 0)
1395 		goto unlock;
1396 
1397 	/* some unit conversions in runtime */
1398 	ep->maxframesize = ep->maxpacksize / ep->cur_frame_bytes;
1399 	ep->curframesize = ep->curpacksize / ep->cur_frame_bytes;
1400 
1401 	err = update_clock_ref_rate(chip, ep);
1402 	if (err >= 0) {
1403 		ep->need_setup = false;
1404 		err = 0;
1405 	}
1406 
1407  unlock:
1408 	mutex_unlock(&chip->mutex);
1409 	return err;
1410 }
1411 
1412 static int init_sample_rate(struct snd_usb_audio *chip,
1413 			    struct snd_usb_endpoint *ep)
1414 {
1415 	struct snd_usb_clock_ref *clock = ep->clock_ref;
1416 	int rate, err;
1417 
1418 	rate = update_clock_ref_rate(chip, ep);
1419 	if (rate < 0)
1420 		return rate;
1421 	if (clock && !clock->need_setup)
1422 		return 0;
1423 
1424 	if (!ep->fixed_rate) {
1425 		err = snd_usb_init_sample_rate(chip, ep->cur_audiofmt, rate);
1426 		if (err < 0) {
1427 			if (clock)
1428 				clock->rate = 0; /* reset rate */
1429 			return err;
1430 		}
1431 	}
1432 
1433 	if (clock)
1434 		clock->need_setup = false;
1435 	return 0;
1436 }
1437 
1438 /*
1439  * snd_usb_endpoint_prepare: Prepare the endpoint
1440  *
1441  * This function sets up the EP to be fully usable state.
1442  * It's called either from prepare callback.
1443  * The function checks need_setup flag, and performs nothing unless needed,
1444  * so it's safe to call this multiple times.
1445  *
1446  * This returns zero if unchanged, 1 if the configuration has changed,
1447  * or a negative error code.
1448  */
1449 int snd_usb_endpoint_prepare(struct snd_usb_audio *chip,
1450 			     struct snd_usb_endpoint *ep)
1451 {
1452 	bool iface_first;
1453 	int err = 0;
1454 
1455 	mutex_lock(&chip->mutex);
1456 	if (WARN_ON(!ep->iface_ref))
1457 		goto unlock;
1458 	if (!ep->need_prepare)
1459 		goto unlock;
1460 
1461 	/* If the interface has been already set up, just set EP parameters */
1462 	if (!ep->iface_ref->need_setup) {
1463 		/* sample rate setup of UAC1 is per endpoint, and we need
1464 		 * to update at each EP configuration
1465 		 */
1466 		if (ep->cur_audiofmt->protocol == UAC_VERSION_1) {
1467 			err = init_sample_rate(chip, ep);
1468 			if (err < 0)
1469 				goto unlock;
1470 		}
1471 		goto done;
1472 	}
1473 
1474 	/* Need to deselect altsetting at first */
1475 	endpoint_set_interface(chip, ep, false);
1476 
1477 	/* Some UAC1 devices (e.g. Yamaha THR10) need the host interface
1478 	 * to be set up before parameter setups
1479 	 */
1480 	iface_first = ep->cur_audiofmt->protocol == UAC_VERSION_1;
1481 	/* Workaround for devices that require the interface setup at first like UAC1 */
1482 	if (chip->quirk_flags & QUIRK_FLAG_SET_IFACE_FIRST)
1483 		iface_first = true;
1484 	if (iface_first) {
1485 		err = endpoint_set_interface(chip, ep, true);
1486 		if (err < 0)
1487 			goto unlock;
1488 	}
1489 
1490 	err = snd_usb_init_pitch(chip, ep->cur_audiofmt);
1491 	if (err < 0)
1492 		goto unlock;
1493 
1494 	err = init_sample_rate(chip, ep);
1495 	if (err < 0)
1496 		goto unlock;
1497 
1498 	err = snd_usb_select_mode_quirk(chip, ep->cur_audiofmt);
1499 	if (err < 0)
1500 		goto unlock;
1501 
1502 	/* for UAC2/3, enable the interface altset here at last */
1503 	if (!iface_first) {
1504 		err = endpoint_set_interface(chip, ep, true);
1505 		if (err < 0)
1506 			goto unlock;
1507 	}
1508 
1509 	ep->iface_ref->need_setup = false;
1510 
1511  done:
1512 	ep->need_prepare = false;
1513 	err = 1;
1514 
1515 unlock:
1516 	mutex_unlock(&chip->mutex);
1517 	return err;
1518 }
1519 
1520 /* get the current rate set to the given clock by any endpoint */
1521 int snd_usb_endpoint_get_clock_rate(struct snd_usb_audio *chip, int clock)
1522 {
1523 	struct snd_usb_clock_ref *ref;
1524 	int rate = 0;
1525 
1526 	if (!clock)
1527 		return 0;
1528 	mutex_lock(&chip->mutex);
1529 	list_for_each_entry(ref, &chip->clock_ref_list, list) {
1530 		if (ref->clock == clock) {
1531 			rate = ref->rate;
1532 			break;
1533 		}
1534 	}
1535 	mutex_unlock(&chip->mutex);
1536 	return rate;
1537 }
1538 
1539 /**
1540  * snd_usb_endpoint_start: start an snd_usb_endpoint
1541  *
1542  * @ep: the endpoint to start
1543  *
1544  * A call to this function will increment the running count of the endpoint.
1545  * In case it is not already running, the URBs for this endpoint will be
1546  * submitted. Otherwise, this function does nothing.
1547  *
1548  * Must be balanced to calls of snd_usb_endpoint_stop().
1549  *
1550  * Returns an error if the URB submission failed, 0 in all other cases.
1551  */
1552 int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
1553 {
1554 	bool is_playback = usb_pipeout(ep->pipe);
1555 	int err;
1556 	unsigned int i;
1557 
1558 	if (atomic_read(&ep->chip->shutdown))
1559 		return -EBADFD;
1560 
1561 	if (ep->sync_source)
1562 		WRITE_ONCE(ep->sync_source->sync_sink, ep);
1563 
1564 	usb_audio_dbg(ep->chip, "Starting %s EP 0x%x (running %d)\n",
1565 		      ep_type_name(ep->type), ep->ep_num,
1566 		      atomic_read(&ep->running));
1567 
1568 	/* already running? */
1569 	if (atomic_inc_return(&ep->running) != 1)
1570 		return 0;
1571 
1572 	if (ep->clock_ref)
1573 		atomic_inc(&ep->clock_ref->locked);
1574 
1575 	ep->active_mask = 0;
1576 	ep->unlink_mask = 0;
1577 	ep->phase = 0;
1578 	ep->sample_accum = 0;
1579 
1580 	snd_usb_endpoint_start_quirk(ep);
1581 
1582 	/*
1583 	 * If this endpoint has a data endpoint as implicit feedback source,
1584 	 * don't start the urbs here. Instead, mark them all as available,
1585 	 * wait for the record urbs to return and queue the playback urbs
1586 	 * from that context.
1587 	 */
1588 
1589 	if (!ep_state_update(ep, EP_STATE_STOPPED, EP_STATE_RUNNING))
1590 		goto __error;
1591 
1592 	if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
1593 	    !(ep->chip->quirk_flags & QUIRK_FLAG_PLAYBACK_FIRST)) {
1594 		usb_audio_dbg(ep->chip, "No URB submission due to implicit fb sync\n");
1595 		i = 0;
1596 		goto fill_rest;
1597 	}
1598 
1599 	for (i = 0; i < ep->nurbs; i++) {
1600 		struct urb *urb = ep->urb[i].urb;
1601 
1602 		if (snd_BUG_ON(!urb))
1603 			goto __error;
1604 
1605 		if (is_playback)
1606 			err = prepare_outbound_urb(ep, urb->context, true);
1607 		else
1608 			err = prepare_inbound_urb(ep, urb->context);
1609 		if (err < 0) {
1610 			/* stop filling at applptr */
1611 			if (err == -EAGAIN)
1612 				break;
1613 			usb_audio_dbg(ep->chip,
1614 				      "EP 0x%x: failed to prepare urb: %d\n",
1615 				      ep->ep_num, err);
1616 			goto __error;
1617 		}
1618 
1619 		if (!atomic_read(&ep->chip->shutdown))
1620 			err = usb_submit_urb(urb, GFP_ATOMIC);
1621 		else
1622 			err = -ENODEV;
1623 		if (err < 0) {
1624 			if (!atomic_read(&ep->chip->shutdown))
1625 				usb_audio_err(ep->chip,
1626 					      "cannot submit urb %d, error %d: %s\n",
1627 					      i, err, usb_error_string(err));
1628 			goto __error;
1629 		}
1630 		set_bit(i, &ep->active_mask);
1631 		atomic_inc(&ep->submitted_urbs);
1632 	}
1633 
1634 	if (!i) {
1635 		usb_audio_dbg(ep->chip, "XRUN at starting EP 0x%x\n",
1636 			      ep->ep_num);
1637 		goto __error;
1638 	}
1639 
1640 	usb_audio_dbg(ep->chip, "%d URBs submitted for EP 0x%x\n",
1641 		      i, ep->ep_num);
1642 
1643  fill_rest:
1644 	/* put the remaining URBs to ready list */
1645 	if (is_playback) {
1646 		for (; i < ep->nurbs; i++)
1647 			push_back_to_ready_list(ep, ep->urb + i);
1648 	}
1649 
1650 	return 0;
1651 
1652 __error:
1653 	snd_usb_endpoint_stop(ep, false);
1654 	return -EPIPE;
1655 }
1656 
1657 /**
1658  * snd_usb_endpoint_stop: stop an snd_usb_endpoint
1659  *
1660  * @ep: the endpoint to stop (may be NULL)
1661  * @keep_pending: keep in-flight URBs
1662  *
1663  * A call to this function will decrement the running count of the endpoint.
1664  * In case the last user has requested the endpoint stop, the URBs will
1665  * actually be deactivated.
1666  *
1667  * Must be balanced to calls of snd_usb_endpoint_start().
1668  *
1669  * The caller needs to synchronize the pending stop operation via
1670  * snd_usb_endpoint_sync_pending_stop().
1671  */
1672 void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep, bool keep_pending)
1673 {
1674 	if (!ep)
1675 		return;
1676 
1677 	usb_audio_dbg(ep->chip, "Stopping %s EP 0x%x (running %d)\n",
1678 		      ep_type_name(ep->type), ep->ep_num,
1679 		      atomic_read(&ep->running));
1680 
1681 	if (snd_BUG_ON(!atomic_read(&ep->running)))
1682 		return;
1683 
1684 	if (!atomic_dec_return(&ep->running)) {
1685 		if (ep->sync_source)
1686 			WRITE_ONCE(ep->sync_source->sync_sink, NULL);
1687 		stop_urbs(ep, false, keep_pending);
1688 		if (ep->clock_ref)
1689 			atomic_dec(&ep->clock_ref->locked);
1690 
1691 		if (ep->chip->quirk_flags & QUIRK_FLAG_FORCE_IFACE_RESET &&
1692 		    usb_pipeout(ep->pipe)) {
1693 			ep->need_prepare = true;
1694 			if (ep->iface_ref)
1695 				ep->iface_ref->need_setup = true;
1696 		}
1697 	}
1698 }
1699 
1700 /**
1701  * snd_usb_endpoint_release: Tear down an snd_usb_endpoint
1702  *
1703  * @ep: the endpoint to release
1704  *
1705  * This function does not care for the endpoint's running count but will tear
1706  * down all the streaming URBs immediately.
1707  */
1708 void snd_usb_endpoint_release(struct snd_usb_endpoint *ep)
1709 {
1710 	release_urbs(ep, true);
1711 }
1712 
1713 /**
1714  * snd_usb_endpoint_free_all: Free the resources of an snd_usb_endpoint
1715  * @chip: The chip
1716  *
1717  * This free all endpoints and those resources
1718  */
1719 void snd_usb_endpoint_free_all(struct snd_usb_audio *chip)
1720 {
1721 	struct snd_usb_endpoint *ep, *en;
1722 	struct snd_usb_iface_ref *ip, *in;
1723 	struct snd_usb_clock_ref *cp, *cn;
1724 
1725 	list_for_each_entry_safe(ep, en, &chip->ep_list, list)
1726 		kfree(ep);
1727 
1728 	list_for_each_entry_safe(ip, in, &chip->iface_ref_list, list)
1729 		kfree(ip);
1730 
1731 	list_for_each_entry_safe(cp, cn, &chip->clock_ref_list, list)
1732 		kfree(cp);
1733 }
1734 
1735 /*
1736  * snd_usb_handle_sync_urb: parse an USB sync packet
1737  *
1738  * @ep: the endpoint to handle the packet
1739  * @sender: the sending endpoint
1740  * @urb: the received packet
1741  *
1742  * This function is called from the context of an endpoint that received
1743  * the packet and is used to let another endpoint object handle the payload.
1744  */
1745 static void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
1746 				    struct snd_usb_endpoint *sender,
1747 				    const struct urb *urb)
1748 {
1749 	int shift;
1750 	unsigned int f;
1751 	unsigned long flags;
1752 
1753 	snd_BUG_ON(ep == sender);
1754 
1755 	/*
1756 	 * In case the endpoint is operating in implicit feedback mode, prepare
1757 	 * a new outbound URB that has the same layout as the received packet
1758 	 * and add it to the list of pending urbs. queue_pending_output_urbs()
1759 	 * will take care of them later.
1760 	 */
1761 	if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
1762 	    atomic_read(&ep->running)) {
1763 
1764 		/* implicit feedback case */
1765 		int i, bytes = 0;
1766 		struct snd_urb_ctx *in_ctx;
1767 		struct snd_usb_packet_info *out_packet;
1768 
1769 		in_ctx = urb->context;
1770 
1771 		/* Count overall packet size */
1772 		for (i = 0; i < in_ctx->packets; i++)
1773 			if (urb->iso_frame_desc[i].status == 0)
1774 				bytes += urb->iso_frame_desc[i].actual_length;
1775 
1776 		/*
1777 		 * skip empty packets. At least M-Audio's Fast Track Ultra stops
1778 		 * streaming once it received a 0-byte OUT URB
1779 		 */
1780 		if (bytes == 0)
1781 			return;
1782 
1783 		spin_lock_irqsave(&ep->lock, flags);
1784 		if (ep->next_packet_queued >= ARRAY_SIZE(ep->next_packet)) {
1785 			spin_unlock_irqrestore(&ep->lock, flags);
1786 			usb_audio_err(ep->chip,
1787 				      "next package FIFO overflow EP 0x%x\n",
1788 				      ep->ep_num);
1789 			notify_xrun(ep);
1790 			return;
1791 		}
1792 
1793 		out_packet = next_packet_fifo_enqueue(ep);
1794 
1795 		/*
1796 		 * Iterate through the inbound packet and prepare the lengths
1797 		 * for the output packet. The OUT packet we are about to send
1798 		 * will have the same amount of payload bytes per stride as the
1799 		 * IN packet we just received. Since the actual size is scaled
1800 		 * by the stride, use the sender stride to calculate the length
1801 		 * in case the number of channels differ between the implicitly
1802 		 * fed-back endpoint and the synchronizing endpoint.
1803 		 */
1804 
1805 		out_packet->packets = in_ctx->packets;
1806 		for (i = 0; i < in_ctx->packets; i++) {
1807 			if (urb->iso_frame_desc[i].status == 0)
1808 				out_packet->packet_size[i] =
1809 					urb->iso_frame_desc[i].actual_length / sender->stride;
1810 			else
1811 				out_packet->packet_size[i] = 0;
1812 		}
1813 
1814 		spin_unlock_irqrestore(&ep->lock, flags);
1815 		snd_usb_queue_pending_output_urbs(ep, false);
1816 
1817 		return;
1818 	}
1819 
1820 	/*
1821 	 * process after playback sync complete
1822 	 *
1823 	 * Full speed devices report feedback values in 10.14 format as samples
1824 	 * per frame, high speed devices in 16.16 format as samples per
1825 	 * microframe.
1826 	 *
1827 	 * Because the Audio Class 1 spec was written before USB 2.0, many high
1828 	 * speed devices use a wrong interpretation, some others use an
1829 	 * entirely different format.
1830 	 *
1831 	 * Therefore, we cannot predict what format any particular device uses
1832 	 * and must detect it automatically.
1833 	 */
1834 
1835 	if (urb->iso_frame_desc[0].status != 0 ||
1836 	    urb->iso_frame_desc[0].actual_length < 3)
1837 		return;
1838 
1839 	f = le32_to_cpup(urb->transfer_buffer);
1840 	if (urb->iso_frame_desc[0].actual_length == 3)
1841 		f &= 0x00ffffff;
1842 	else
1843 		f &= 0x0fffffff;
1844 
1845 	if (f == 0)
1846 		return;
1847 
1848 	if (unlikely(sender->tenor_fb_quirk)) {
1849 		/*
1850 		 * Devices based on Tenor 8802 chipsets (TEAC UD-H01
1851 		 * and others) sometimes change the feedback value
1852 		 * by +/- 0x1.0000.
1853 		 */
1854 		if (f < ep->freqn - 0x8000)
1855 			f += 0xf000;
1856 		else if (f > ep->freqn + 0x8000)
1857 			f -= 0xf000;
1858 	} else if (unlikely(ep->freqshift == INT_MIN)) {
1859 		/*
1860 		 * The first time we see a feedback value, determine its format
1861 		 * by shifting it left or right until it matches the nominal
1862 		 * frequency value.  This assumes that the feedback does not
1863 		 * differ from the nominal value more than +50% or -25%.
1864 		 */
1865 		shift = 0;
1866 		while (f < ep->freqn - ep->freqn / 4) {
1867 			f <<= 1;
1868 			shift++;
1869 		}
1870 		while (f > ep->freqn + ep->freqn / 2) {
1871 			f >>= 1;
1872 			shift--;
1873 		}
1874 		ep->freqshift = shift;
1875 	} else if (ep->freqshift >= 0)
1876 		f <<= ep->freqshift;
1877 	else
1878 		f >>= -ep->freqshift;
1879 
1880 	if (likely(f >= ep->freqn - ep->freqn / 8 && f <= ep->freqmax)) {
1881 		/*
1882 		 * If the frequency looks valid, set it.
1883 		 * This value is referred to in prepare_playback_urb().
1884 		 */
1885 		spin_lock_irqsave(&ep->lock, flags);
1886 		ep->freqm = f;
1887 		spin_unlock_irqrestore(&ep->lock, flags);
1888 	} else {
1889 		/*
1890 		 * Out of range; maybe the shift value is wrong.
1891 		 * Reset it so that we autodetect again the next time.
1892 		 */
1893 		ep->freqshift = INT_MIN;
1894 	}
1895 }
1896 
1897