xref: /openbmc/linux/sound/usb/usx2y/usb_stream.c (revision 63dc02bd)
1 /*
2  * Copyright (C) 2007, 2008 Karsten Wiese <fzu@wemgehoertderstaat.de>
3  *
4  * This program is free software; you can redistribute it and/or modify it
5  * under the terms of the GNU General Public License as published by the
6  * Free Software Foundation; either version 2 of the License, or (at your
7  * option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful, but
10  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
11  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software Foundation,
16  * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17  */
18 
19 #include <linux/usb.h>
20 #include <linux/gfp.h>
21 
22 #include "usb_stream.h"
23 
24 
25 /*                             setup                                  */
26 
27 static unsigned usb_stream_next_packet_size(struct usb_stream_kernel *sk)
28 {
29 	struct usb_stream *s = sk->s;
30 	sk->out_phase_peeked = (sk->out_phase & 0xffff) + sk->freqn;
31 	return (sk->out_phase_peeked >> 16) * s->cfg.frame_size;
32 }
33 
34 static void playback_prep_freqn(struct usb_stream_kernel *sk, struct urb *urb)
35 {
36 	struct usb_stream *s = sk->s;
37 	int pack, lb = 0;
38 
39 	for (pack = 0; pack < sk->n_o_ps; pack++) {
40 		int l = usb_stream_next_packet_size(sk);
41 		if (s->idle_outsize + lb + l > s->period_size)
42 			goto check;
43 
44 		sk->out_phase = sk->out_phase_peeked;
45 		urb->iso_frame_desc[pack].offset = lb;
46 		urb->iso_frame_desc[pack].length = l;
47 		lb += l;
48 	}
49 	snd_printdd(KERN_DEBUG "%i\n", lb);
50 
51 check:
52 	urb->number_of_packets = pack;
53 	urb->transfer_buffer_length = lb;
54 	s->idle_outsize += lb - s->period_size;
55 	snd_printdd(KERN_DEBUG "idle=%i ul=%i ps=%i\n", s->idle_outsize,
56 		    lb, s->period_size);
57 }
58 
59 static void init_pipe_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
60 			   struct urb **urbs, char *transfer,
61 			   struct usb_device *dev, int pipe)
62 {
63 	int u, p;
64 	int maxpacket = use_packsize ?
65 		use_packsize : usb_maxpacket(dev, pipe, usb_pipeout(pipe));
66 	int transfer_length = maxpacket * sk->n_o_ps;
67 
68 	for (u = 0; u < USB_STREAM_NURBS;
69 	     ++u, transfer += transfer_length) {
70 		struct urb *urb = urbs[u];
71 		struct usb_iso_packet_descriptor *desc;
72 		urb->transfer_flags = URB_ISO_ASAP;
73 		urb->transfer_buffer = transfer;
74 		urb->dev = dev;
75 		urb->pipe = pipe;
76 		urb->number_of_packets = sk->n_o_ps;
77 		urb->context = sk;
78 		urb->interval = 1;
79 		if (usb_pipeout(pipe))
80 			continue;
81 
82 		urb->transfer_buffer_length = transfer_length;
83 		desc = urb->iso_frame_desc;
84 		desc->offset = 0;
85 		desc->length = maxpacket;
86 		for (p = 1; p < sk->n_o_ps; ++p) {
87 			desc[p].offset = desc[p - 1].offset + maxpacket;
88 			desc[p].length = maxpacket;
89 		}
90 	}
91 }
92 
93 static void init_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
94 		      struct usb_device *dev, int in_pipe, int out_pipe)
95 {
96 	struct usb_stream	*s = sk->s;
97 	char			*indata = (char *)s + sizeof(*s) +
98 					sizeof(struct usb_stream_packet) *
99 					s->inpackets;
100 	int			u;
101 
102 	for (u = 0; u < USB_STREAM_NURBS; ++u) {
103 		sk->inurb[u] = usb_alloc_urb(sk->n_o_ps, GFP_KERNEL);
104 		sk->outurb[u] = usb_alloc_urb(sk->n_o_ps, GFP_KERNEL);
105 	}
106 
107 	init_pipe_urbs(sk, use_packsize, sk->inurb, indata, dev, in_pipe);
108 	init_pipe_urbs(sk, use_packsize, sk->outurb, sk->write_page, dev,
109 		       out_pipe);
110 }
111 
112 
113 /*
114  * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
115  * this will overflow at approx 524 kHz
116  */
117 static inline unsigned get_usb_full_speed_rate(unsigned rate)
118 {
119 	return ((rate << 13) + 62) / 125;
120 }
121 
122 /*
123  * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
124  * this will overflow at approx 4 MHz
125  */
126 static inline unsigned get_usb_high_speed_rate(unsigned rate)
127 {
128 	return ((rate << 10) + 62) / 125;
129 }
130 
131 void usb_stream_free(struct usb_stream_kernel *sk)
132 {
133 	struct usb_stream *s;
134 	unsigned u;
135 
136 	for (u = 0; u < USB_STREAM_NURBS; ++u) {
137 		usb_free_urb(sk->inurb[u]);
138 		sk->inurb[u] = NULL;
139 		usb_free_urb(sk->outurb[u]);
140 		sk->outurb[u] = NULL;
141 	}
142 
143 	s = sk->s;
144 	if (!s)
145 		return;
146 
147 	free_pages((unsigned long)sk->write_page, get_order(s->write_size));
148 	sk->write_page = NULL;
149 	free_pages((unsigned long)s, get_order(s->read_size));
150 	sk->s = NULL;
151 }
152 
153 struct usb_stream *usb_stream_new(struct usb_stream_kernel *sk,
154 				  struct usb_device *dev,
155 				  unsigned in_endpoint, unsigned out_endpoint,
156 				  unsigned sample_rate, unsigned use_packsize,
157 				  unsigned period_frames, unsigned frame_size)
158 {
159 	int packets, max_packsize;
160 	int in_pipe, out_pipe;
161 	int read_size = sizeof(struct usb_stream);
162 	int write_size;
163 	int usb_frames = dev->speed == USB_SPEED_HIGH ? 8000 : 1000;
164 	int pg;
165 
166 	in_pipe = usb_rcvisocpipe(dev, in_endpoint);
167 	out_pipe = usb_sndisocpipe(dev, out_endpoint);
168 
169 	max_packsize = use_packsize ?
170 		use_packsize : usb_maxpacket(dev, in_pipe, 0);
171 
172 	/*
173 		t_period = period_frames / sample_rate
174 		iso_packs = t_period / t_iso_frame
175 			= (period_frames / sample_rate) * (1 / t_iso_frame)
176 	*/
177 
178 	packets = period_frames * usb_frames / sample_rate + 1;
179 
180 	if (dev->speed == USB_SPEED_HIGH)
181 		packets = (packets + 7) & ~7;
182 
183 	read_size += packets * USB_STREAM_URBDEPTH *
184 		(max_packsize + sizeof(struct usb_stream_packet));
185 
186 	max_packsize = usb_maxpacket(dev, out_pipe, 1);
187 	write_size = max_packsize * packets * USB_STREAM_URBDEPTH;
188 
189 	if (read_size >= 256*PAGE_SIZE || write_size >= 256*PAGE_SIZE) {
190 		snd_printk(KERN_WARNING "a size exceeds 128*PAGE_SIZE\n");
191 		goto out;
192 	}
193 
194 	pg = get_order(read_size);
195 	sk->s = (void *) __get_free_pages(GFP_KERNEL|__GFP_COMP|__GFP_ZERO, pg);
196 	if (!sk->s) {
197 		snd_printk(KERN_WARNING "couldn't __get_free_pages()\n");
198 		goto out;
199 	}
200 	sk->s->cfg.version = USB_STREAM_INTERFACE_VERSION;
201 
202 	sk->s->read_size = read_size;
203 
204 	sk->s->cfg.sample_rate = sample_rate;
205 	sk->s->cfg.frame_size = frame_size;
206 	sk->n_o_ps = packets;
207 	sk->s->inpackets = packets * USB_STREAM_URBDEPTH;
208 	sk->s->cfg.period_frames = period_frames;
209 	sk->s->period_size = frame_size * period_frames;
210 
211 	sk->s->write_size = write_size;
212 	pg = get_order(write_size);
213 
214 	sk->write_page =
215 		(void *)__get_free_pages(GFP_KERNEL|__GFP_COMP|__GFP_ZERO, pg);
216 	if (!sk->write_page) {
217 		snd_printk(KERN_WARNING "couldn't __get_free_pages()\n");
218 		usb_stream_free(sk);
219 		return NULL;
220 	}
221 
222 	/* calculate the frequency in 16.16 format */
223 	if (dev->speed == USB_SPEED_FULL)
224 		sk->freqn = get_usb_full_speed_rate(sample_rate);
225 	else
226 		sk->freqn = get_usb_high_speed_rate(sample_rate);
227 
228 	init_urbs(sk, use_packsize, dev, in_pipe, out_pipe);
229 	sk->s->state = usb_stream_stopped;
230 out:
231 	return sk->s;
232 }
233 
234 
235 /*                             start                                  */
236 
237 static bool balance_check(struct usb_stream_kernel *sk, struct urb *urb)
238 {
239 	bool r;
240 	if (unlikely(urb->status)) {
241 		if (urb->status != -ESHUTDOWN && urb->status != -ENOENT)
242 			snd_printk(KERN_WARNING "status=%i\n", urb->status);
243 		sk->iso_frame_balance = 0x7FFFFFFF;
244 		return false;
245 	}
246 	r = sk->iso_frame_balance == 0;
247 	if (!r)
248 		sk->i_urb = urb;
249 	return r;
250 }
251 
252 static bool balance_playback(struct usb_stream_kernel *sk, struct urb *urb)
253 {
254 	sk->iso_frame_balance += urb->number_of_packets;
255 	return balance_check(sk, urb);
256 }
257 
258 static bool balance_capture(struct usb_stream_kernel *sk, struct urb *urb)
259 {
260 	sk->iso_frame_balance -= urb->number_of_packets;
261 	return balance_check(sk, urb);
262 }
263 
264 static void subs_set_complete(struct urb **urbs, void (*complete)(struct urb *))
265 {
266 	int u;
267 
268 	for (u = 0; u < USB_STREAM_NURBS; u++) {
269 		struct urb *urb = urbs[u];
270 		urb->complete = complete;
271 	}
272 }
273 
274 static int usb_stream_prepare_playback(struct usb_stream_kernel *sk,
275 		struct urb *inurb)
276 {
277 	struct usb_stream *s = sk->s;
278 	struct urb *io;
279 	struct usb_iso_packet_descriptor *id, *od;
280 	int p = 0, lb = 0, l = 0;
281 
282 	io = sk->idle_outurb;
283 	od = io->iso_frame_desc;
284 
285 	for (; s->sync_packet < 0; ++p, ++s->sync_packet) {
286 		struct urb *ii = sk->completed_inurb;
287 		id = ii->iso_frame_desc +
288 			ii->number_of_packets + s->sync_packet;
289 		l = id->actual_length;
290 
291 		od[p].length = l;
292 		od[p].offset = lb;
293 		lb += l;
294 	}
295 
296 	for (;
297 	     s->sync_packet < inurb->number_of_packets && p < sk->n_o_ps;
298 	     ++p, ++s->sync_packet) {
299 		l = inurb->iso_frame_desc[s->sync_packet].actual_length;
300 
301 		if (s->idle_outsize + lb + l > s->period_size)
302 			goto check_ok;
303 
304 		od[p].length = l;
305 		od[p].offset = lb;
306 		lb += l;
307 	}
308 
309 check_ok:
310 	s->sync_packet -= inurb->number_of_packets;
311 	if (unlikely(s->sync_packet < -2 || s->sync_packet > 0)) {
312 		snd_printk(KERN_WARNING "invalid sync_packet = %i;"
313 			   " p=%i nop=%i %i %x %x %x > %x\n",
314 			   s->sync_packet, p, inurb->number_of_packets,
315 			   s->idle_outsize + lb + l,
316 			   s->idle_outsize, lb,  l,
317 			   s->period_size);
318 		return -1;
319 	}
320 	if (unlikely(lb % s->cfg.frame_size)) {
321 		snd_printk(KERN_WARNING"invalid outsize = %i\n",
322 			   lb);
323 		return -1;
324 	}
325 	s->idle_outsize += lb - s->period_size;
326 	io->number_of_packets = p;
327 	io->transfer_buffer_length = lb;
328 	if (s->idle_outsize <= 0)
329 		return 0;
330 
331 	snd_printk(KERN_WARNING "idle=%i\n", s->idle_outsize);
332 	return -1;
333 }
334 
335 static void prepare_inurb(int number_of_packets, struct urb *iu)
336 {
337 	struct usb_iso_packet_descriptor *id;
338 	int p;
339 
340 	iu->number_of_packets = number_of_packets;
341 	id = iu->iso_frame_desc;
342 	id->offset = 0;
343 	for (p = 0; p < iu->number_of_packets - 1; ++p)
344 		id[p + 1].offset = id[p].offset + id[p].length;
345 
346 	iu->transfer_buffer_length =
347 		id[0].length * iu->number_of_packets;
348 }
349 
350 static int submit_urbs(struct usb_stream_kernel *sk,
351 		       struct urb *inurb, struct urb *outurb)
352 {
353 	int err;
354 	prepare_inurb(sk->idle_outurb->number_of_packets, sk->idle_inurb);
355 	err = usb_submit_urb(sk->idle_inurb, GFP_ATOMIC);
356 	if (err < 0) {
357 		snd_printk(KERN_ERR "%i\n", err);
358 		return err;
359 	}
360 	sk->idle_inurb = sk->completed_inurb;
361 	sk->completed_inurb = inurb;
362 	err = usb_submit_urb(sk->idle_outurb, GFP_ATOMIC);
363 	if (err < 0) {
364 		snd_printk(KERN_ERR "%i\n", err);
365 		return err;
366 	}
367 	sk->idle_outurb = sk->completed_outurb;
368 	sk->completed_outurb = outurb;
369 	return 0;
370 }
371 
372 #ifdef DEBUG_LOOP_BACK
373 /*
374   This loop_back() shows how to read/write the period data.
375  */
376 static void loop_back(struct usb_stream *s)
377 {
378 	char *i, *o;
379 	int il, ol, l, p;
380 	struct urb *iu;
381 	struct usb_iso_packet_descriptor *id;
382 
383 	o = s->playback1st_to;
384 	ol = s->playback1st_size;
385 	l = 0;
386 
387 	if (s->insplit_pack >= 0) {
388 		iu = sk->idle_inurb;
389 		id = iu->iso_frame_desc;
390 		p = s->insplit_pack;
391 	} else
392 		goto second;
393 loop:
394 	for (; p < iu->number_of_packets && l < s->period_size; ++p) {
395 		i = iu->transfer_buffer + id[p].offset;
396 		il = id[p].actual_length;
397 		if (l + il > s->period_size)
398 			il = s->period_size - l;
399 		if (il <= ol) {
400 			memcpy(o, i, il);
401 			o += il;
402 			ol -= il;
403 		} else {
404 			memcpy(o, i, ol);
405 			singen_6pack(o, ol);
406 			o = s->playback_to;
407 			memcpy(o, i + ol, il - ol);
408 			o += il - ol;
409 			ol = s->period_size - s->playback1st_size;
410 		}
411 		l += il;
412 	}
413 	if (iu == sk->completed_inurb) {
414 		if (l != s->period_size)
415 			printk(KERN_DEBUG"%s:%i %i\n", __func__, __LINE__,
416 			       l/(int)s->cfg.frame_size);
417 
418 		return;
419 	}
420 second:
421 	iu = sk->completed_inurb;
422 	id = iu->iso_frame_desc;
423 	p = 0;
424 	goto loop;
425 
426 }
427 #else
428 static void loop_back(struct usb_stream *s)
429 {
430 }
431 #endif
432 
433 static void stream_idle(struct usb_stream_kernel *sk,
434 			struct urb *inurb, struct urb *outurb)
435 {
436 	struct usb_stream *s = sk->s;
437 	int l, p;
438 	int insize = s->idle_insize;
439 	int urb_size = 0;
440 
441 	s->inpacket_split = s->next_inpacket_split;
442 	s->inpacket_split_at = s->next_inpacket_split_at;
443 	s->next_inpacket_split = -1;
444 	s->next_inpacket_split_at = 0;
445 
446 	for (p = 0; p < inurb->number_of_packets; ++p) {
447 		struct usb_iso_packet_descriptor *id = inurb->iso_frame_desc;
448 		l = id[p].actual_length;
449 		if (unlikely(l == 0 || id[p].status)) {
450 			snd_printk(KERN_WARNING "underrun, status=%u\n",
451 				   id[p].status);
452 			goto err_out;
453 		}
454 		s->inpacket_head++;
455 		s->inpacket_head %= s->inpackets;
456 		if (s->inpacket_split == -1)
457 			s->inpacket_split = s->inpacket_head;
458 
459 		s->inpacket[s->inpacket_head].offset =
460 			id[p].offset + (inurb->transfer_buffer - (void *)s);
461 		s->inpacket[s->inpacket_head].length = l;
462 		if (insize + l > s->period_size &&
463 		    s->next_inpacket_split == -1) {
464 			s->next_inpacket_split = s->inpacket_head;
465 			s->next_inpacket_split_at = s->period_size - insize;
466 		}
467 		insize += l;
468 		urb_size += l;
469 	}
470 	s->idle_insize += urb_size - s->period_size;
471 	if (s->idle_insize < 0) {
472 		snd_printk(KERN_WARNING "%i\n",
473 			   (s->idle_insize)/(int)s->cfg.frame_size);
474 		goto err_out;
475 	}
476 	s->insize_done += urb_size;
477 
478 	l = s->idle_outsize;
479 	s->outpacket[0].offset = (sk->idle_outurb->transfer_buffer -
480 				  sk->write_page) - l;
481 
482 	if (usb_stream_prepare_playback(sk, inurb) < 0)
483 		goto err_out;
484 
485 	s->outpacket[0].length = sk->idle_outurb->transfer_buffer_length + l;
486 	s->outpacket[1].offset = sk->completed_outurb->transfer_buffer -
487 		sk->write_page;
488 
489 	if (submit_urbs(sk, inurb, outurb) < 0)
490 		goto err_out;
491 
492 	loop_back(s);
493 	s->periods_done++;
494 	wake_up_all(&sk->sleep);
495 	return;
496 err_out:
497 	s->state = usb_stream_xrun;
498 	wake_up_all(&sk->sleep);
499 }
500 
501 static void i_capture_idle(struct urb *urb)
502 {
503 	struct usb_stream_kernel *sk = urb->context;
504 	if (balance_capture(sk, urb))
505 		stream_idle(sk, urb, sk->i_urb);
506 }
507 
508 static void i_playback_idle(struct urb *urb)
509 {
510 	struct usb_stream_kernel *sk = urb->context;
511 	if (balance_playback(sk, urb))
512 		stream_idle(sk, sk->i_urb, urb);
513 }
514 
515 static void stream_start(struct usb_stream_kernel *sk,
516 			 struct urb *inurb, struct urb *outurb)
517 {
518 	struct usb_stream *s = sk->s;
519 	if (s->state >= usb_stream_sync1) {
520 		int l, p, max_diff, max_diff_0;
521 		int urb_size = 0;
522 		unsigned frames_per_packet, min_frames = 0;
523 		frames_per_packet = (s->period_size - s->idle_insize);
524 		frames_per_packet <<= 8;
525 		frames_per_packet /=
526 			s->cfg.frame_size * inurb->number_of_packets;
527 		frames_per_packet++;
528 
529 		max_diff_0 = s->cfg.frame_size;
530 		if (s->cfg.period_frames >= 256)
531 			max_diff_0 <<= 1;
532 		if (s->cfg.period_frames >= 1024)
533 			max_diff_0 <<= 1;
534 		max_diff = max_diff_0;
535 		for (p = 0; p < inurb->number_of_packets; ++p) {
536 			int diff;
537 			l = inurb->iso_frame_desc[p].actual_length;
538 			urb_size += l;
539 
540 			min_frames += frames_per_packet;
541 			diff = urb_size -
542 				(min_frames >> 8) * s->cfg.frame_size;
543 			if (diff < max_diff) {
544 				snd_printdd(KERN_DEBUG "%i %i %i %i\n",
545 					    s->insize_done,
546 					    urb_size / (int)s->cfg.frame_size,
547 					    inurb->number_of_packets, diff);
548 				max_diff = diff;
549 			}
550 		}
551 		s->idle_insize -= max_diff - max_diff_0;
552 		s->idle_insize += urb_size - s->period_size;
553 		if (s->idle_insize < 0) {
554 			snd_printk(KERN_WARNING "%i %i %i\n",
555 				   s->idle_insize, urb_size, s->period_size);
556 			return;
557 		} else if (s->idle_insize == 0) {
558 			s->next_inpacket_split =
559 				(s->inpacket_head + 1) % s->inpackets;
560 			s->next_inpacket_split_at = 0;
561 		} else {
562 			unsigned split = s->inpacket_head;
563 			l = s->idle_insize;
564 			while (l > s->inpacket[split].length) {
565 				l -= s->inpacket[split].length;
566 				if (split == 0)
567 					split = s->inpackets - 1;
568 				else
569 					split--;
570 			}
571 			s->next_inpacket_split = split;
572 			s->next_inpacket_split_at =
573 				s->inpacket[split].length - l;
574 		}
575 
576 		s->insize_done += urb_size;
577 
578 		if (usb_stream_prepare_playback(sk, inurb) < 0)
579 			return;
580 
581 	} else
582 		playback_prep_freqn(sk, sk->idle_outurb);
583 
584 	if (submit_urbs(sk, inurb, outurb) < 0)
585 		return;
586 
587 	if (s->state == usb_stream_sync1 && s->insize_done > 360000) {
588 		/* just guesswork                            ^^^^^^ */
589 		s->state = usb_stream_ready;
590 		subs_set_complete(sk->inurb, i_capture_idle);
591 		subs_set_complete(sk->outurb, i_playback_idle);
592 	}
593 }
594 
595 static void i_capture_start(struct urb *urb)
596 {
597 	struct usb_iso_packet_descriptor *id = urb->iso_frame_desc;
598 	struct usb_stream_kernel *sk = urb->context;
599 	struct usb_stream *s = sk->s;
600 	int p;
601 	int empty = 0;
602 
603 	if (urb->status) {
604 		snd_printk(KERN_WARNING "status=%i\n", urb->status);
605 		return;
606 	}
607 
608 	for (p = 0; p < urb->number_of_packets; ++p) {
609 		int l = id[p].actual_length;
610 		if (l < s->cfg.frame_size) {
611 			++empty;
612 			if (s->state >= usb_stream_sync0) {
613 				snd_printk(KERN_WARNING "%i\n", l);
614 				return;
615 			}
616 		}
617 		s->inpacket_head++;
618 		s->inpacket_head %= s->inpackets;
619 		s->inpacket[s->inpacket_head].offset =
620 			id[p].offset + (urb->transfer_buffer - (void *)s);
621 		s->inpacket[s->inpacket_head].length = l;
622 	}
623 #ifdef SHOW_EMPTY
624 	if (empty) {
625 		printk(KERN_DEBUG"%s:%i: %i", __func__, __LINE__,
626 		       urb->iso_frame_desc[0].actual_length);
627 		for (pack = 1; pack < urb->number_of_packets; ++pack) {
628 			int l = urb->iso_frame_desc[pack].actual_length;
629 			printk(" %i", l);
630 		}
631 		printk("\n");
632 	}
633 #endif
634 	if (!empty && s->state < usb_stream_sync1)
635 		++s->state;
636 
637 	if (balance_capture(sk, urb))
638 		stream_start(sk, urb, sk->i_urb);
639 }
640 
641 static void i_playback_start(struct urb *urb)
642 {
643 	struct usb_stream_kernel *sk = urb->context;
644 	if (balance_playback(sk, urb))
645 		stream_start(sk, sk->i_urb, urb);
646 }
647 
648 int usb_stream_start(struct usb_stream_kernel *sk)
649 {
650 	struct usb_stream *s = sk->s;
651 	int frame = 0, iters = 0;
652 	int u, err;
653 	int try = 0;
654 
655 	if (s->state != usb_stream_stopped)
656 		return -EAGAIN;
657 
658 	subs_set_complete(sk->inurb, i_capture_start);
659 	subs_set_complete(sk->outurb, i_playback_start);
660 	memset(sk->write_page, 0, s->write_size);
661 dotry:
662 	s->insize_done = 0;
663 	s->idle_insize = 0;
664 	s->idle_outsize = 0;
665 	s->sync_packet = -1;
666 	s->inpacket_head = -1;
667 	sk->iso_frame_balance = 0;
668 	++try;
669 	for (u = 0; u < 2; u++) {
670 		struct urb *inurb = sk->inurb[u];
671 		struct urb *outurb = sk->outurb[u];
672 		playback_prep_freqn(sk, outurb);
673 		inurb->number_of_packets = outurb->number_of_packets;
674 		inurb->transfer_buffer_length =
675 			inurb->number_of_packets *
676 			inurb->iso_frame_desc[0].length;
677 
678 		if (u == 0) {
679 			int now;
680 			struct usb_device *dev = inurb->dev;
681 			frame = usb_get_current_frame_number(dev);
682 			do {
683 				now = usb_get_current_frame_number(dev);
684 				++iters;
685 			} while (now > -1 && now == frame);
686 		}
687 		err = usb_submit_urb(inurb, GFP_ATOMIC);
688 		if (err < 0) {
689 			snd_printk(KERN_ERR"usb_submit_urb(sk->inurb[%i])"
690 				   " returned %i\n", u, err);
691 			return err;
692 		}
693 		err = usb_submit_urb(outurb, GFP_ATOMIC);
694 		if (err < 0) {
695 			snd_printk(KERN_ERR"usb_submit_urb(sk->outurb[%i])"
696 				   " returned %i\n", u, err);
697 			return err;
698 		}
699 
700 		if (inurb->start_frame != outurb->start_frame) {
701 			snd_printd(KERN_DEBUG
702 				   "u[%i] start_frames differ in:%u out:%u\n",
703 				   u, inurb->start_frame, outurb->start_frame);
704 			goto check_retry;
705 		}
706 	}
707 	snd_printdd(KERN_DEBUG "%i %i\n", frame, iters);
708 	try = 0;
709 check_retry:
710 	if (try) {
711 		usb_stream_stop(sk);
712 		if (try < 5) {
713 			msleep(1500);
714 			snd_printd(KERN_DEBUG "goto dotry;\n");
715 			goto dotry;
716 		}
717 		snd_printk(KERN_WARNING"couldn't start"
718 			   " all urbs on the same start_frame.\n");
719 		return -EFAULT;
720 	}
721 
722 	sk->idle_inurb = sk->inurb[USB_STREAM_NURBS - 2];
723 	sk->idle_outurb = sk->outurb[USB_STREAM_NURBS - 2];
724 	sk->completed_inurb = sk->inurb[USB_STREAM_NURBS - 1];
725 	sk->completed_outurb = sk->outurb[USB_STREAM_NURBS - 1];
726 
727 /* wait, check */
728 	{
729 		int wait_ms = 3000;
730 		while (s->state != usb_stream_ready && wait_ms > 0) {
731 			snd_printdd(KERN_DEBUG "%i\n", s->state);
732 			msleep(200);
733 			wait_ms -= 200;
734 		}
735 	}
736 
737 	return s->state == usb_stream_ready ? 0 : -EFAULT;
738 }
739 
740 
741 /*                             stop                                   */
742 
743 void usb_stream_stop(struct usb_stream_kernel *sk)
744 {
745 	int u;
746 	if (!sk->s)
747 		return;
748 	for (u = 0; u < USB_STREAM_NURBS; ++u) {
749 		usb_kill_urb(sk->inurb[u]);
750 		usb_kill_urb(sk->outurb[u]);
751 	}
752 	sk->s->state = usb_stream_stopped;
753 	msleep(400);
754 }
755