xref: /openbmc/linux/sound/usb/usx2y/usb_stream.c (revision be2b81b5)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2007, 2008 Karsten Wiese <fzu@wemgehoertderstaat.de>
4  */
5 
6 #include <linux/usb.h>
7 #include <linux/gfp.h>
8 
9 #include "usb_stream.h"
10 
11 /*                             setup                                  */
12 
13 static unsigned int usb_stream_next_packet_size(struct usb_stream_kernel *sk)
14 {
15 	struct usb_stream *s = sk->s;
16 
17 	sk->out_phase_peeked = (sk->out_phase & 0xffff) + sk->freqn;
18 	return (sk->out_phase_peeked >> 16) * s->cfg.frame_size;
19 }
20 
21 static void playback_prep_freqn(struct usb_stream_kernel *sk, struct urb *urb)
22 {
23 	struct usb_stream *s = sk->s;
24 	int pack, lb = 0;
25 
26 	for (pack = 0; pack < sk->n_o_ps; pack++) {
27 		int l = usb_stream_next_packet_size(sk);
28 
29 		if (s->idle_outsize + lb + l > s->period_size)
30 			goto check;
31 
32 		sk->out_phase = sk->out_phase_peeked;
33 		urb->iso_frame_desc[pack].offset = lb;
34 		urb->iso_frame_desc[pack].length = l;
35 		lb += l;
36 	}
37 	snd_printdd(KERN_DEBUG "%i\n", lb);
38 
39 check:
40 	urb->number_of_packets = pack;
41 	urb->transfer_buffer_length = lb;
42 	s->idle_outsize += lb - s->period_size;
43 	snd_printdd(KERN_DEBUG "idle=%i ul=%i ps=%i\n", s->idle_outsize,
44 		    lb, s->period_size);
45 }
46 
47 static int init_pipe_urbs(struct usb_stream_kernel *sk,
48 			  unsigned int use_packsize,
49 			  struct urb **urbs, char *transfer,
50 			  struct usb_device *dev, int pipe)
51 {
52 	int u, p;
53 	int maxpacket = use_packsize ?
54 		use_packsize : usb_maxpacket(dev, pipe);
55 	int transfer_length = maxpacket * sk->n_o_ps;
56 
57 	for (u = 0; u < USB_STREAM_NURBS;
58 	     ++u, transfer += transfer_length) {
59 		struct urb *urb = urbs[u];
60 		struct usb_iso_packet_descriptor *desc;
61 
62 		urb->transfer_buffer = transfer;
63 		urb->dev = dev;
64 		urb->pipe = pipe;
65 		urb->number_of_packets = sk->n_o_ps;
66 		urb->context = sk;
67 		urb->interval = 1;
68 		if (usb_pipeout(pipe))
69 			continue;
70 		if (usb_urb_ep_type_check(urb))
71 			return -EINVAL;
72 
73 		urb->transfer_buffer_length = transfer_length;
74 		desc = urb->iso_frame_desc;
75 		desc->offset = 0;
76 		desc->length = maxpacket;
77 		for (p = 1; p < sk->n_o_ps; ++p) {
78 			desc[p].offset = desc[p - 1].offset + maxpacket;
79 			desc[p].length = maxpacket;
80 		}
81 	}
82 
83 	return 0;
84 }
85 
86 static int init_urbs(struct usb_stream_kernel *sk, unsigned int use_packsize,
87 		     struct usb_device *dev, int in_pipe, int out_pipe)
88 {
89 	struct usb_stream	*s = sk->s;
90 	char			*indata =
91 		(char *)s + sizeof(*s) + sizeof(struct usb_stream_packet) * s->inpackets;
92 	int			u;
93 
94 	for (u = 0; u < USB_STREAM_NURBS; ++u) {
95 		sk->inurb[u] = usb_alloc_urb(sk->n_o_ps, GFP_KERNEL);
96 		if (!sk->inurb[u])
97 			return -ENOMEM;
98 
99 		sk->outurb[u] = usb_alloc_urb(sk->n_o_ps, GFP_KERNEL);
100 		if (!sk->outurb[u])
101 			return -ENOMEM;
102 	}
103 
104 	if (init_pipe_urbs(sk, use_packsize, sk->inurb, indata, dev, in_pipe) ||
105 	    init_pipe_urbs(sk, use_packsize, sk->outurb, sk->write_page, dev,
106 			   out_pipe))
107 		return -EINVAL;
108 
109 	return 0;
110 }
111 
112 /*
113  * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
114  * this will overflow at approx 524 kHz
115  */
116 static inline unsigned int get_usb_full_speed_rate(unsigned int rate)
117 {
118 	return ((rate << 13) + 62) / 125;
119 }
120 
121 /*
122  * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
123  * this will overflow at approx 4 MHz
124  */
125 static inline unsigned int get_usb_high_speed_rate(unsigned int rate)
126 {
127 	return ((rate << 10) + 62) / 125;
128 }
129 
130 void usb_stream_free(struct usb_stream_kernel *sk)
131 {
132 	struct usb_stream *s;
133 	unsigned int u;
134 
135 	for (u = 0; u < USB_STREAM_NURBS; ++u) {
136 		usb_free_urb(sk->inurb[u]);
137 		sk->inurb[u] = NULL;
138 		usb_free_urb(sk->outurb[u]);
139 		sk->outurb[u] = NULL;
140 	}
141 
142 	s = sk->s;
143 	if (!s)
144 		return;
145 
146 	if (sk->write_page) {
147 		free_pages_exact(sk->write_page, s->write_size);
148 		sk->write_page = NULL;
149 	}
150 
151 	free_pages_exact(s, s->read_size);
152 	sk->s = NULL;
153 }
154 
155 struct usb_stream *usb_stream_new(struct usb_stream_kernel *sk,
156 				  struct usb_device *dev,
157 				  unsigned int in_endpoint,
158 				  unsigned int out_endpoint,
159 				  unsigned int sample_rate,
160 				  unsigned int use_packsize,
161 				  unsigned int period_frames,
162 				  unsigned int frame_size)
163 {
164 	int packets, max_packsize;
165 	int in_pipe, out_pipe;
166 	int read_size = sizeof(struct usb_stream);
167 	int write_size;
168 	int usb_frames = dev->speed == USB_SPEED_HIGH ? 8000 : 1000;
169 
170 	in_pipe = usb_rcvisocpipe(dev, in_endpoint);
171 	out_pipe = usb_sndisocpipe(dev, out_endpoint);
172 
173 	max_packsize = use_packsize ?
174 		use_packsize : usb_maxpacket(dev, in_pipe);
175 
176 	/*
177 		t_period = period_frames / sample_rate
178 		iso_packs = t_period / t_iso_frame
179 			= (period_frames / sample_rate) * (1 / t_iso_frame)
180 	*/
181 
182 	packets = period_frames * usb_frames / sample_rate + 1;
183 
184 	if (dev->speed == USB_SPEED_HIGH)
185 		packets = (packets + 7) & ~7;
186 
187 	read_size += packets * USB_STREAM_URBDEPTH *
188 		(max_packsize + sizeof(struct usb_stream_packet));
189 
190 	max_packsize = usb_maxpacket(dev, out_pipe);
191 	write_size = max_packsize * packets * USB_STREAM_URBDEPTH;
192 
193 	if (read_size >= 256*PAGE_SIZE || write_size >= 256*PAGE_SIZE) {
194 		snd_printk(KERN_WARNING "a size exceeds 128*PAGE_SIZE\n");
195 		goto out;
196 	}
197 
198 	sk->s = alloc_pages_exact(read_size,
199 				  GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN);
200 	if (!sk->s) {
201 		pr_warn("us122l: couldn't allocate read buffer\n");
202 		goto out;
203 	}
204 	sk->s->cfg.version = USB_STREAM_INTERFACE_VERSION;
205 
206 	sk->s->read_size = read_size;
207 
208 	sk->s->cfg.sample_rate = sample_rate;
209 	sk->s->cfg.frame_size = frame_size;
210 	sk->n_o_ps = packets;
211 	sk->s->inpackets = packets * USB_STREAM_URBDEPTH;
212 	sk->s->cfg.period_frames = period_frames;
213 	sk->s->period_size = frame_size * period_frames;
214 
215 	sk->s->write_size = write_size;
216 
217 	sk->write_page = alloc_pages_exact(write_size,
218 					   GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN);
219 	if (!sk->write_page) {
220 		pr_warn("us122l: couldn't allocate write buffer\n");
221 		usb_stream_free(sk);
222 		return NULL;
223 	}
224 
225 	/* calculate the frequency in 16.16 format */
226 	if (dev->speed == USB_SPEED_FULL)
227 		sk->freqn = get_usb_full_speed_rate(sample_rate);
228 	else
229 		sk->freqn = get_usb_high_speed_rate(sample_rate);
230 
231 	if (init_urbs(sk, use_packsize, dev, in_pipe, out_pipe) < 0) {
232 		usb_stream_free(sk);
233 		return NULL;
234 	}
235 
236 	sk->s->state = usb_stream_stopped;
237 out:
238 	return sk->s;
239 }
240 
241 /*                             start                                  */
242 
243 static bool balance_check(struct usb_stream_kernel *sk, struct urb *urb)
244 {
245 	bool r;
246 
247 	if (unlikely(urb->status)) {
248 		if (urb->status != -ESHUTDOWN && urb->status != -ENOENT)
249 			snd_printk(KERN_WARNING "status=%i\n", urb->status);
250 		sk->iso_frame_balance = 0x7FFFFFFF;
251 		return false;
252 	}
253 	r = sk->iso_frame_balance == 0;
254 	if (!r)
255 		sk->i_urb = urb;
256 	return r;
257 }
258 
259 static bool balance_playback(struct usb_stream_kernel *sk, struct urb *urb)
260 {
261 	sk->iso_frame_balance += urb->number_of_packets;
262 	return balance_check(sk, urb);
263 }
264 
265 static bool balance_capture(struct usb_stream_kernel *sk, struct urb *urb)
266 {
267 	sk->iso_frame_balance -= urb->number_of_packets;
268 	return balance_check(sk, urb);
269 }
270 
271 static void subs_set_complete(struct urb **urbs, void (*complete)(struct urb *))
272 {
273 	int u;
274 
275 	for (u = 0; u < USB_STREAM_NURBS; u++) {
276 		struct urb *urb = urbs[u];
277 
278 		urb->complete = complete;
279 	}
280 }
281 
282 static int usb_stream_prepare_playback(struct usb_stream_kernel *sk,
283 		struct urb *inurb)
284 {
285 	struct usb_stream *s = sk->s;
286 	struct urb *io;
287 	struct usb_iso_packet_descriptor *id, *od;
288 	int p = 0, lb = 0, l = 0;
289 
290 	io = sk->idle_outurb;
291 	od = io->iso_frame_desc;
292 
293 	for (; s->sync_packet < 0; ++p, ++s->sync_packet) {
294 		struct urb *ii = sk->completed_inurb;
295 
296 		id = ii->iso_frame_desc +
297 			ii->number_of_packets + s->sync_packet;
298 		l = id->actual_length;
299 
300 		od[p].length = l;
301 		od[p].offset = lb;
302 		lb += l;
303 	}
304 
305 	for (;
306 	     s->sync_packet < inurb->number_of_packets && p < sk->n_o_ps;
307 	     ++p, ++s->sync_packet) {
308 		l = inurb->iso_frame_desc[s->sync_packet].actual_length;
309 
310 		if (s->idle_outsize + lb + l > s->period_size)
311 			goto check_ok;
312 
313 		od[p].length = l;
314 		od[p].offset = lb;
315 		lb += l;
316 	}
317 
318 check_ok:
319 	s->sync_packet -= inurb->number_of_packets;
320 	if (unlikely(s->sync_packet < -2 || s->sync_packet > 0)) {
321 		snd_printk(KERN_WARNING "invalid sync_packet = %i;"
322 			   " p=%i nop=%i %i %x %x %x > %x\n",
323 			   s->sync_packet, p, inurb->number_of_packets,
324 			   s->idle_outsize + lb + l,
325 			   s->idle_outsize, lb,  l,
326 			   s->period_size);
327 		return -1;
328 	}
329 	if (unlikely(lb % s->cfg.frame_size)) {
330 		snd_printk(KERN_WARNING"invalid outsize = %i\n",
331 			   lb);
332 		return -1;
333 	}
334 	s->idle_outsize += lb - s->period_size;
335 	io->number_of_packets = p;
336 	io->transfer_buffer_length = lb;
337 	if (s->idle_outsize <= 0)
338 		return 0;
339 
340 	snd_printk(KERN_WARNING "idle=%i\n", s->idle_outsize);
341 	return -1;
342 }
343 
344 static void prepare_inurb(int number_of_packets, struct urb *iu)
345 {
346 	struct usb_iso_packet_descriptor *id;
347 	int p;
348 
349 	iu->number_of_packets = number_of_packets;
350 	id = iu->iso_frame_desc;
351 	id->offset = 0;
352 	for (p = 0; p < iu->number_of_packets - 1; ++p)
353 		id[p + 1].offset = id[p].offset + id[p].length;
354 
355 	iu->transfer_buffer_length =
356 		id[0].length * iu->number_of_packets;
357 }
358 
359 static int submit_urbs(struct usb_stream_kernel *sk,
360 		       struct urb *inurb, struct urb *outurb)
361 {
362 	int err;
363 
364 	prepare_inurb(sk->idle_outurb->number_of_packets, sk->idle_inurb);
365 	err = usb_submit_urb(sk->idle_inurb, GFP_ATOMIC);
366 	if (err < 0)
367 		goto report_failure;
368 
369 	sk->idle_inurb = sk->completed_inurb;
370 	sk->completed_inurb = inurb;
371 	err = usb_submit_urb(sk->idle_outurb, GFP_ATOMIC);
372 	if (err < 0)
373 		goto report_failure;
374 
375 	sk->idle_outurb = sk->completed_outurb;
376 	sk->completed_outurb = outurb;
377 	return 0;
378 
379 report_failure:
380 	snd_printk(KERN_ERR "%i\n", err);
381 	return err;
382 }
383 
384 #ifdef DEBUG_LOOP_BACK
385 /*
386   This loop_back() shows how to read/write the period data.
387  */
388 static void loop_back(struct usb_stream *s)
389 {
390 	char *i, *o;
391 	int il, ol, l, p;
392 	struct urb *iu;
393 	struct usb_iso_packet_descriptor *id;
394 
395 	o = s->playback1st_to;
396 	ol = s->playback1st_size;
397 	l = 0;
398 
399 	if (s->insplit_pack >= 0) {
400 		iu = sk->idle_inurb;
401 		id = iu->iso_frame_desc;
402 		p = s->insplit_pack;
403 	} else
404 		goto second;
405 loop:
406 	for (; p < iu->number_of_packets && l < s->period_size; ++p) {
407 		i = iu->transfer_buffer + id[p].offset;
408 		il = id[p].actual_length;
409 		if (l + il > s->period_size)
410 			il = s->period_size - l;
411 		if (il <= ol) {
412 			memcpy(o, i, il);
413 			o += il;
414 			ol -= il;
415 		} else {
416 			memcpy(o, i, ol);
417 			singen_6pack(o, ol);
418 			o = s->playback_to;
419 			memcpy(o, i + ol, il - ol);
420 			o += il - ol;
421 			ol = s->period_size - s->playback1st_size;
422 		}
423 		l += il;
424 	}
425 	if (iu == sk->completed_inurb) {
426 		if (l != s->period_size)
427 			printk(KERN_DEBUG"%s:%i %i\n", __func__, __LINE__,
428 			       l/(int)s->cfg.frame_size);
429 
430 		return;
431 	}
432 second:
433 	iu = sk->completed_inurb;
434 	id = iu->iso_frame_desc;
435 	p = 0;
436 	goto loop;
437 
438 }
439 #else
440 static void loop_back(struct usb_stream *s)
441 {
442 }
443 #endif
444 
445 static void stream_idle(struct usb_stream_kernel *sk,
446 			struct urb *inurb, struct urb *outurb)
447 {
448 	struct usb_stream *s = sk->s;
449 	int l, p;
450 	int insize = s->idle_insize;
451 	int urb_size = 0;
452 
453 	s->inpacket_split = s->next_inpacket_split;
454 	s->inpacket_split_at = s->next_inpacket_split_at;
455 	s->next_inpacket_split = -1;
456 	s->next_inpacket_split_at = 0;
457 
458 	for (p = 0; p < inurb->number_of_packets; ++p) {
459 		struct usb_iso_packet_descriptor *id = inurb->iso_frame_desc;
460 
461 		l = id[p].actual_length;
462 		if (unlikely(l == 0 || id[p].status)) {
463 			snd_printk(KERN_WARNING "underrun, status=%u\n",
464 				   id[p].status);
465 			goto err_out;
466 		}
467 		s->inpacket_head++;
468 		s->inpacket_head %= s->inpackets;
469 		if (s->inpacket_split == -1)
470 			s->inpacket_split = s->inpacket_head;
471 
472 		s->inpacket[s->inpacket_head].offset =
473 			id[p].offset + (inurb->transfer_buffer - (void *)s);
474 		s->inpacket[s->inpacket_head].length = l;
475 		if (insize + l > s->period_size &&
476 		    s->next_inpacket_split == -1) {
477 			s->next_inpacket_split = s->inpacket_head;
478 			s->next_inpacket_split_at = s->period_size - insize;
479 		}
480 		insize += l;
481 		urb_size += l;
482 	}
483 	s->idle_insize += urb_size - s->period_size;
484 	if (s->idle_insize < 0) {
485 		snd_printk(KERN_WARNING "%i\n",
486 			   (s->idle_insize)/(int)s->cfg.frame_size);
487 		goto err_out;
488 	}
489 	s->insize_done += urb_size;
490 
491 	l = s->idle_outsize;
492 	s->outpacket[0].offset = (sk->idle_outurb->transfer_buffer -
493 				  sk->write_page) - l;
494 
495 	if (usb_stream_prepare_playback(sk, inurb) < 0)
496 		goto err_out;
497 
498 	s->outpacket[0].length = sk->idle_outurb->transfer_buffer_length + l;
499 	s->outpacket[1].offset = sk->completed_outurb->transfer_buffer -
500 		sk->write_page;
501 
502 	if (submit_urbs(sk, inurb, outurb) < 0)
503 		goto err_out;
504 
505 	loop_back(s);
506 	s->periods_done++;
507 	wake_up_all(&sk->sleep);
508 	return;
509 err_out:
510 	s->state = usb_stream_xrun;
511 	wake_up_all(&sk->sleep);
512 }
513 
514 static void i_capture_idle(struct urb *urb)
515 {
516 	struct usb_stream_kernel *sk = urb->context;
517 
518 	if (balance_capture(sk, urb))
519 		stream_idle(sk, urb, sk->i_urb);
520 }
521 
522 static void i_playback_idle(struct urb *urb)
523 {
524 	struct usb_stream_kernel *sk = urb->context;
525 
526 	if (balance_playback(sk, urb))
527 		stream_idle(sk, sk->i_urb, urb);
528 }
529 
530 static void stream_start(struct usb_stream_kernel *sk,
531 			 struct urb *inurb, struct urb *outurb)
532 {
533 	struct usb_stream *s = sk->s;
534 
535 	if (s->state >= usb_stream_sync1) {
536 		int l, p, max_diff, max_diff_0;
537 		int urb_size = 0;
538 		unsigned int frames_per_packet, min_frames = 0;
539 
540 		frames_per_packet = (s->period_size - s->idle_insize);
541 		frames_per_packet <<= 8;
542 		frames_per_packet /=
543 			s->cfg.frame_size * inurb->number_of_packets;
544 		frames_per_packet++;
545 
546 		max_diff_0 = s->cfg.frame_size;
547 		if (s->cfg.period_frames >= 256)
548 			max_diff_0 <<= 1;
549 		if (s->cfg.period_frames >= 1024)
550 			max_diff_0 <<= 1;
551 		max_diff = max_diff_0;
552 		for (p = 0; p < inurb->number_of_packets; ++p) {
553 			int diff;
554 
555 			l = inurb->iso_frame_desc[p].actual_length;
556 			urb_size += l;
557 
558 			min_frames += frames_per_packet;
559 			diff = urb_size -
560 				(min_frames >> 8) * s->cfg.frame_size;
561 			if (diff < max_diff) {
562 				snd_printdd(KERN_DEBUG "%i %i %i %i\n",
563 					    s->insize_done,
564 					    urb_size / (int)s->cfg.frame_size,
565 					    inurb->number_of_packets, diff);
566 				max_diff = diff;
567 			}
568 		}
569 		s->idle_insize -= max_diff - max_diff_0;
570 		s->idle_insize += urb_size - s->period_size;
571 		if (s->idle_insize < 0) {
572 			snd_printk(KERN_WARNING "%i %i %i\n",
573 				   s->idle_insize, urb_size, s->period_size);
574 			return;
575 		} else if (s->idle_insize == 0) {
576 			s->next_inpacket_split =
577 				(s->inpacket_head + 1) % s->inpackets;
578 			s->next_inpacket_split_at = 0;
579 		} else {
580 			unsigned int split = s->inpacket_head;
581 
582 			l = s->idle_insize;
583 			while (l > s->inpacket[split].length) {
584 				l -= s->inpacket[split].length;
585 				if (split == 0)
586 					split = s->inpackets - 1;
587 				else
588 					split--;
589 			}
590 			s->next_inpacket_split = split;
591 			s->next_inpacket_split_at =
592 				s->inpacket[split].length - l;
593 		}
594 
595 		s->insize_done += urb_size;
596 
597 		if (usb_stream_prepare_playback(sk, inurb) < 0)
598 			return;
599 
600 	} else
601 		playback_prep_freqn(sk, sk->idle_outurb);
602 
603 	if (submit_urbs(sk, inurb, outurb) < 0)
604 		return;
605 
606 	if (s->state == usb_stream_sync1 && s->insize_done > 360000) {
607 		/* just guesswork                            ^^^^^^ */
608 		s->state = usb_stream_ready;
609 		subs_set_complete(sk->inurb, i_capture_idle);
610 		subs_set_complete(sk->outurb, i_playback_idle);
611 	}
612 }
613 
614 static void i_capture_start(struct urb *urb)
615 {
616 	struct usb_iso_packet_descriptor *id = urb->iso_frame_desc;
617 	struct usb_stream_kernel *sk = urb->context;
618 	struct usb_stream *s = sk->s;
619 	int p;
620 	int empty = 0;
621 
622 	if (urb->status) {
623 		snd_printk(KERN_WARNING "status=%i\n", urb->status);
624 		return;
625 	}
626 
627 	for (p = 0; p < urb->number_of_packets; ++p) {
628 		int l = id[p].actual_length;
629 
630 		if (l < s->cfg.frame_size) {
631 			++empty;
632 			if (s->state >= usb_stream_sync0) {
633 				snd_printk(KERN_WARNING "%i\n", l);
634 				return;
635 			}
636 		}
637 		s->inpacket_head++;
638 		s->inpacket_head %= s->inpackets;
639 		s->inpacket[s->inpacket_head].offset =
640 			id[p].offset + (urb->transfer_buffer - (void *)s);
641 		s->inpacket[s->inpacket_head].length = l;
642 	}
643 #ifdef SHOW_EMPTY
644 	if (empty) {
645 		printk(KERN_DEBUG"%s:%i: %i", __func__, __LINE__,
646 		       urb->iso_frame_desc[0].actual_length);
647 		for (pack = 1; pack < urb->number_of_packets; ++pack) {
648 			int l = urb->iso_frame_desc[pack].actual_length;
649 
650 			printk(KERN_CONT " %i", l);
651 		}
652 		printk(KERN_CONT "\n");
653 	}
654 #endif
655 	if (!empty && s->state < usb_stream_sync1)
656 		++s->state;
657 
658 	if (balance_capture(sk, urb))
659 		stream_start(sk, urb, sk->i_urb);
660 }
661 
662 static void i_playback_start(struct urb *urb)
663 {
664 	struct usb_stream_kernel *sk = urb->context;
665 
666 	if (balance_playback(sk, urb))
667 		stream_start(sk, sk->i_urb, urb);
668 }
669 
670 int usb_stream_start(struct usb_stream_kernel *sk)
671 {
672 	struct usb_stream *s = sk->s;
673 	int frame = 0, iters = 0;
674 	int u, err;
675 	int try = 0;
676 
677 	if (s->state != usb_stream_stopped)
678 		return -EAGAIN;
679 
680 	subs_set_complete(sk->inurb, i_capture_start);
681 	subs_set_complete(sk->outurb, i_playback_start);
682 	memset(sk->write_page, 0, s->write_size);
683 dotry:
684 	s->insize_done = 0;
685 	s->idle_insize = 0;
686 	s->idle_outsize = 0;
687 	s->sync_packet = -1;
688 	s->inpacket_head = -1;
689 	sk->iso_frame_balance = 0;
690 	++try;
691 	for (u = 0; u < 2; u++) {
692 		struct urb *inurb = sk->inurb[u];
693 		struct urb *outurb = sk->outurb[u];
694 
695 		playback_prep_freqn(sk, outurb);
696 		inurb->number_of_packets = outurb->number_of_packets;
697 		inurb->transfer_buffer_length =
698 			inurb->number_of_packets *
699 			inurb->iso_frame_desc[0].length;
700 
701 		if (u == 0) {
702 			int now;
703 			struct usb_device *dev = inurb->dev;
704 
705 			frame = usb_get_current_frame_number(dev);
706 			do {
707 				now = usb_get_current_frame_number(dev);
708 				++iters;
709 			} while (now > -1 && now == frame);
710 		}
711 		err = usb_submit_urb(inurb, GFP_ATOMIC);
712 		if (err < 0) {
713 			snd_printk(KERN_ERR
714 				   "usb_submit_urb(sk->inurb[%i]) returned %i\n",
715 				   u, err);
716 			return err;
717 		}
718 		err = usb_submit_urb(outurb, GFP_ATOMIC);
719 		if (err < 0) {
720 			snd_printk(KERN_ERR
721 				   "usb_submit_urb(sk->outurb[%i]) returned %i\n",
722 				   u, err);
723 			return err;
724 		}
725 
726 		if (inurb->start_frame != outurb->start_frame) {
727 			snd_printd(KERN_DEBUG
728 				   "u[%i] start_frames differ in:%u out:%u\n",
729 				   u, inurb->start_frame, outurb->start_frame);
730 			goto check_retry;
731 		}
732 	}
733 	snd_printdd(KERN_DEBUG "%i %i\n", frame, iters);
734 	try = 0;
735 check_retry:
736 	if (try) {
737 		usb_stream_stop(sk);
738 		if (try < 5) {
739 			msleep(1500);
740 			snd_printd(KERN_DEBUG "goto dotry;\n");
741 			goto dotry;
742 		}
743 		snd_printk(KERN_WARNING
744 			   "couldn't start all urbs on the same start_frame.\n");
745 		return -EFAULT;
746 	}
747 
748 	sk->idle_inurb = sk->inurb[USB_STREAM_NURBS - 2];
749 	sk->idle_outurb = sk->outurb[USB_STREAM_NURBS - 2];
750 	sk->completed_inurb = sk->inurb[USB_STREAM_NURBS - 1];
751 	sk->completed_outurb = sk->outurb[USB_STREAM_NURBS - 1];
752 
753 /* wait, check */
754 	{
755 		int wait_ms = 3000;
756 
757 		while (s->state != usb_stream_ready && wait_ms > 0) {
758 			snd_printdd(KERN_DEBUG "%i\n", s->state);
759 			msleep(200);
760 			wait_ms -= 200;
761 		}
762 	}
763 
764 	return s->state == usb_stream_ready ? 0 : -EFAULT;
765 }
766 
767 
768 /*                             stop                                   */
769 
770 void usb_stream_stop(struct usb_stream_kernel *sk)
771 {
772 	int u;
773 
774 	if (!sk->s)
775 		return;
776 	for (u = 0; u < USB_STREAM_NURBS; ++u) {
777 		usb_kill_urb(sk->inurb[u]);
778 		usb_kill_urb(sk->outurb[u]);
779 	}
780 	sk->s->state = usb_stream_stopped;
781 	msleep(400);
782 }
783