xref: /openbmc/linux/sound/usb/usx2y/usb_stream.c (revision 293d5b43)
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_buffer = transfer;
73 		urb->dev = dev;
74 		urb->pipe = pipe;
75 		urb->number_of_packets = sk->n_o_ps;
76 		urb->context = sk;
77 		urb->interval = 1;
78 		if (usb_pipeout(pipe))
79 			continue;
80 
81 		urb->transfer_buffer_length = transfer_length;
82 		desc = urb->iso_frame_desc;
83 		desc->offset = 0;
84 		desc->length = maxpacket;
85 		for (p = 1; p < sk->n_o_ps; ++p) {
86 			desc[p].offset = desc[p - 1].offset + maxpacket;
87 			desc[p].length = maxpacket;
88 		}
89 	}
90 }
91 
92 static void init_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
93 		      struct usb_device *dev, int in_pipe, int out_pipe)
94 {
95 	struct usb_stream	*s = sk->s;
96 	char			*indata = (char *)s + sizeof(*s) +
97 					sizeof(struct usb_stream_packet) *
98 					s->inpackets;
99 	int			u;
100 
101 	for (u = 0; u < USB_STREAM_NURBS; ++u) {
102 		sk->inurb[u] = usb_alloc_urb(sk->n_o_ps, GFP_KERNEL);
103 		sk->outurb[u] = usb_alloc_urb(sk->n_o_ps, GFP_KERNEL);
104 	}
105 
106 	init_pipe_urbs(sk, use_packsize, sk->inurb, indata, dev, in_pipe);
107 	init_pipe_urbs(sk, use_packsize, sk->outurb, sk->write_page, dev,
108 		       out_pipe);
109 }
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 get_usb_full_speed_rate(unsigned 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 get_usb_high_speed_rate(unsigned 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 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 	free_pages((unsigned long)sk->write_page, get_order(s->write_size));
147 	sk->write_page = NULL;
148 	free_pages((unsigned long)s, get_order(s->read_size));
149 	sk->s = NULL;
150 }
151 
152 struct usb_stream *usb_stream_new(struct usb_stream_kernel *sk,
153 				  struct usb_device *dev,
154 				  unsigned in_endpoint, unsigned out_endpoint,
155 				  unsigned sample_rate, unsigned use_packsize,
156 				  unsigned period_frames, unsigned frame_size)
157 {
158 	int packets, max_packsize;
159 	int in_pipe, out_pipe;
160 	int read_size = sizeof(struct usb_stream);
161 	int write_size;
162 	int usb_frames = dev->speed == USB_SPEED_HIGH ? 8000 : 1000;
163 	int pg;
164 
165 	in_pipe = usb_rcvisocpipe(dev, in_endpoint);
166 	out_pipe = usb_sndisocpipe(dev, out_endpoint);
167 
168 	max_packsize = use_packsize ?
169 		use_packsize : usb_maxpacket(dev, in_pipe, 0);
170 
171 	/*
172 		t_period = period_frames / sample_rate
173 		iso_packs = t_period / t_iso_frame
174 			= (period_frames / sample_rate) * (1 / t_iso_frame)
175 	*/
176 
177 	packets = period_frames * usb_frames / sample_rate + 1;
178 
179 	if (dev->speed == USB_SPEED_HIGH)
180 		packets = (packets + 7) & ~7;
181 
182 	read_size += packets * USB_STREAM_URBDEPTH *
183 		(max_packsize + sizeof(struct usb_stream_packet));
184 
185 	max_packsize = usb_maxpacket(dev, out_pipe, 1);
186 	write_size = max_packsize * packets * USB_STREAM_URBDEPTH;
187 
188 	if (read_size >= 256*PAGE_SIZE || write_size >= 256*PAGE_SIZE) {
189 		snd_printk(KERN_WARNING "a size exceeds 128*PAGE_SIZE\n");
190 		goto out;
191 	}
192 
193 	pg = get_order(read_size);
194 	sk->s = (void *) __get_free_pages(GFP_KERNEL|__GFP_COMP|__GFP_ZERO, pg);
195 	if (!sk->s) {
196 		snd_printk(KERN_WARNING "couldn't __get_free_pages()\n");
197 		goto out;
198 	}
199 	sk->s->cfg.version = USB_STREAM_INTERFACE_VERSION;
200 
201 	sk->s->read_size = read_size;
202 
203 	sk->s->cfg.sample_rate = sample_rate;
204 	sk->s->cfg.frame_size = frame_size;
205 	sk->n_o_ps = packets;
206 	sk->s->inpackets = packets * USB_STREAM_URBDEPTH;
207 	sk->s->cfg.period_frames = period_frames;
208 	sk->s->period_size = frame_size * period_frames;
209 
210 	sk->s->write_size = write_size;
211 	pg = get_order(write_size);
212 
213 	sk->write_page =
214 		(void *)__get_free_pages(GFP_KERNEL|__GFP_COMP|__GFP_ZERO, pg);
215 	if (!sk->write_page) {
216 		snd_printk(KERN_WARNING "couldn't __get_free_pages()\n");
217 		usb_stream_free(sk);
218 		return NULL;
219 	}
220 
221 	/* calculate the frequency in 16.16 format */
222 	if (dev->speed == USB_SPEED_FULL)
223 		sk->freqn = get_usb_full_speed_rate(sample_rate);
224 	else
225 		sk->freqn = get_usb_high_speed_rate(sample_rate);
226 
227 	init_urbs(sk, use_packsize, dev, in_pipe, out_pipe);
228 	sk->s->state = usb_stream_stopped;
229 out:
230 	return sk->s;
231 }
232 
233 
234 /*                             start                                  */
235 
236 static bool balance_check(struct usb_stream_kernel *sk, struct urb *urb)
237 {
238 	bool r;
239 	if (unlikely(urb->status)) {
240 		if (urb->status != -ESHUTDOWN && urb->status != -ENOENT)
241 			snd_printk(KERN_WARNING "status=%i\n", urb->status);
242 		sk->iso_frame_balance = 0x7FFFFFFF;
243 		return false;
244 	}
245 	r = sk->iso_frame_balance == 0;
246 	if (!r)
247 		sk->i_urb = urb;
248 	return r;
249 }
250 
251 static bool balance_playback(struct usb_stream_kernel *sk, struct urb *urb)
252 {
253 	sk->iso_frame_balance += urb->number_of_packets;
254 	return balance_check(sk, urb);
255 }
256 
257 static bool balance_capture(struct usb_stream_kernel *sk, struct urb *urb)
258 {
259 	sk->iso_frame_balance -= urb->number_of_packets;
260 	return balance_check(sk, urb);
261 }
262 
263 static void subs_set_complete(struct urb **urbs, void (*complete)(struct urb *))
264 {
265 	int u;
266 
267 	for (u = 0; u < USB_STREAM_NURBS; u++) {
268 		struct urb *urb = urbs[u];
269 		urb->complete = complete;
270 	}
271 }
272 
273 static int usb_stream_prepare_playback(struct usb_stream_kernel *sk,
274 		struct urb *inurb)
275 {
276 	struct usb_stream *s = sk->s;
277 	struct urb *io;
278 	struct usb_iso_packet_descriptor *id, *od;
279 	int p = 0, lb = 0, l = 0;
280 
281 	io = sk->idle_outurb;
282 	od = io->iso_frame_desc;
283 
284 	for (; s->sync_packet < 0; ++p, ++s->sync_packet) {
285 		struct urb *ii = sk->completed_inurb;
286 		id = ii->iso_frame_desc +
287 			ii->number_of_packets + s->sync_packet;
288 		l = id->actual_length;
289 
290 		od[p].length = l;
291 		od[p].offset = lb;
292 		lb += l;
293 	}
294 
295 	for (;
296 	     s->sync_packet < inurb->number_of_packets && p < sk->n_o_ps;
297 	     ++p, ++s->sync_packet) {
298 		l = inurb->iso_frame_desc[s->sync_packet].actual_length;
299 
300 		if (s->idle_outsize + lb + l > s->period_size)
301 			goto check_ok;
302 
303 		od[p].length = l;
304 		od[p].offset = lb;
305 		lb += l;
306 	}
307 
308 check_ok:
309 	s->sync_packet -= inurb->number_of_packets;
310 	if (unlikely(s->sync_packet < -2 || s->sync_packet > 0)) {
311 		snd_printk(KERN_WARNING "invalid sync_packet = %i;"
312 			   " p=%i nop=%i %i %x %x %x > %x\n",
313 			   s->sync_packet, p, inurb->number_of_packets,
314 			   s->idle_outsize + lb + l,
315 			   s->idle_outsize, lb,  l,
316 			   s->period_size);
317 		return -1;
318 	}
319 	if (unlikely(lb % s->cfg.frame_size)) {
320 		snd_printk(KERN_WARNING"invalid outsize = %i\n",
321 			   lb);
322 		return -1;
323 	}
324 	s->idle_outsize += lb - s->period_size;
325 	io->number_of_packets = p;
326 	io->transfer_buffer_length = lb;
327 	if (s->idle_outsize <= 0)
328 		return 0;
329 
330 	snd_printk(KERN_WARNING "idle=%i\n", s->idle_outsize);
331 	return -1;
332 }
333 
334 static void prepare_inurb(int number_of_packets, struct urb *iu)
335 {
336 	struct usb_iso_packet_descriptor *id;
337 	int p;
338 
339 	iu->number_of_packets = number_of_packets;
340 	id = iu->iso_frame_desc;
341 	id->offset = 0;
342 	for (p = 0; p < iu->number_of_packets - 1; ++p)
343 		id[p + 1].offset = id[p].offset + id[p].length;
344 
345 	iu->transfer_buffer_length =
346 		id[0].length * iu->number_of_packets;
347 }
348 
349 static int submit_urbs(struct usb_stream_kernel *sk,
350 		       struct urb *inurb, struct urb *outurb)
351 {
352 	int err;
353 	prepare_inurb(sk->idle_outurb->number_of_packets, sk->idle_inurb);
354 	err = usb_submit_urb(sk->idle_inurb, GFP_ATOMIC);
355 	if (err < 0) {
356 		snd_printk(KERN_ERR "%i\n", err);
357 		return err;
358 	}
359 	sk->idle_inurb = sk->completed_inurb;
360 	sk->completed_inurb = inurb;
361 	err = usb_submit_urb(sk->idle_outurb, GFP_ATOMIC);
362 	if (err < 0) {
363 		snd_printk(KERN_ERR "%i\n", err);
364 		return err;
365 	}
366 	sk->idle_outurb = sk->completed_outurb;
367 	sk->completed_outurb = outurb;
368 	return 0;
369 }
370 
371 #ifdef DEBUG_LOOP_BACK
372 /*
373   This loop_back() shows how to read/write the period data.
374  */
375 static void loop_back(struct usb_stream *s)
376 {
377 	char *i, *o;
378 	int il, ol, l, p;
379 	struct urb *iu;
380 	struct usb_iso_packet_descriptor *id;
381 
382 	o = s->playback1st_to;
383 	ol = s->playback1st_size;
384 	l = 0;
385 
386 	if (s->insplit_pack >= 0) {
387 		iu = sk->idle_inurb;
388 		id = iu->iso_frame_desc;
389 		p = s->insplit_pack;
390 	} else
391 		goto second;
392 loop:
393 	for (; p < iu->number_of_packets && l < s->period_size; ++p) {
394 		i = iu->transfer_buffer + id[p].offset;
395 		il = id[p].actual_length;
396 		if (l + il > s->period_size)
397 			il = s->period_size - l;
398 		if (il <= ol) {
399 			memcpy(o, i, il);
400 			o += il;
401 			ol -= il;
402 		} else {
403 			memcpy(o, i, ol);
404 			singen_6pack(o, ol);
405 			o = s->playback_to;
406 			memcpy(o, i + ol, il - ol);
407 			o += il - ol;
408 			ol = s->period_size - s->playback1st_size;
409 		}
410 		l += il;
411 	}
412 	if (iu == sk->completed_inurb) {
413 		if (l != s->period_size)
414 			printk(KERN_DEBUG"%s:%i %i\n", __func__, __LINE__,
415 			       l/(int)s->cfg.frame_size);
416 
417 		return;
418 	}
419 second:
420 	iu = sk->completed_inurb;
421 	id = iu->iso_frame_desc;
422 	p = 0;
423 	goto loop;
424 
425 }
426 #else
427 static void loop_back(struct usb_stream *s)
428 {
429 }
430 #endif
431 
432 static void stream_idle(struct usb_stream_kernel *sk,
433 			struct urb *inurb, struct urb *outurb)
434 {
435 	struct usb_stream *s = sk->s;
436 	int l, p;
437 	int insize = s->idle_insize;
438 	int urb_size = 0;
439 
440 	s->inpacket_split = s->next_inpacket_split;
441 	s->inpacket_split_at = s->next_inpacket_split_at;
442 	s->next_inpacket_split = -1;
443 	s->next_inpacket_split_at = 0;
444 
445 	for (p = 0; p < inurb->number_of_packets; ++p) {
446 		struct usb_iso_packet_descriptor *id = inurb->iso_frame_desc;
447 		l = id[p].actual_length;
448 		if (unlikely(l == 0 || id[p].status)) {
449 			snd_printk(KERN_WARNING "underrun, status=%u\n",
450 				   id[p].status);
451 			goto err_out;
452 		}
453 		s->inpacket_head++;
454 		s->inpacket_head %= s->inpackets;
455 		if (s->inpacket_split == -1)
456 			s->inpacket_split = s->inpacket_head;
457 
458 		s->inpacket[s->inpacket_head].offset =
459 			id[p].offset + (inurb->transfer_buffer - (void *)s);
460 		s->inpacket[s->inpacket_head].length = l;
461 		if (insize + l > s->period_size &&
462 		    s->next_inpacket_split == -1) {
463 			s->next_inpacket_split = s->inpacket_head;
464 			s->next_inpacket_split_at = s->period_size - insize;
465 		}
466 		insize += l;
467 		urb_size += l;
468 	}
469 	s->idle_insize += urb_size - s->period_size;
470 	if (s->idle_insize < 0) {
471 		snd_printk(KERN_WARNING "%i\n",
472 			   (s->idle_insize)/(int)s->cfg.frame_size);
473 		goto err_out;
474 	}
475 	s->insize_done += urb_size;
476 
477 	l = s->idle_outsize;
478 	s->outpacket[0].offset = (sk->idle_outurb->transfer_buffer -
479 				  sk->write_page) - l;
480 
481 	if (usb_stream_prepare_playback(sk, inurb) < 0)
482 		goto err_out;
483 
484 	s->outpacket[0].length = sk->idle_outurb->transfer_buffer_length + l;
485 	s->outpacket[1].offset = sk->completed_outurb->transfer_buffer -
486 		sk->write_page;
487 
488 	if (submit_urbs(sk, inurb, outurb) < 0)
489 		goto err_out;
490 
491 	loop_back(s);
492 	s->periods_done++;
493 	wake_up_all(&sk->sleep);
494 	return;
495 err_out:
496 	s->state = usb_stream_xrun;
497 	wake_up_all(&sk->sleep);
498 }
499 
500 static void i_capture_idle(struct urb *urb)
501 {
502 	struct usb_stream_kernel *sk = urb->context;
503 	if (balance_capture(sk, urb))
504 		stream_idle(sk, urb, sk->i_urb);
505 }
506 
507 static void i_playback_idle(struct urb *urb)
508 {
509 	struct usb_stream_kernel *sk = urb->context;
510 	if (balance_playback(sk, urb))
511 		stream_idle(sk, sk->i_urb, urb);
512 }
513 
514 static void stream_start(struct usb_stream_kernel *sk,
515 			 struct urb *inurb, struct urb *outurb)
516 {
517 	struct usb_stream *s = sk->s;
518 	if (s->state >= usb_stream_sync1) {
519 		int l, p, max_diff, max_diff_0;
520 		int urb_size = 0;
521 		unsigned frames_per_packet, min_frames = 0;
522 		frames_per_packet = (s->period_size - s->idle_insize);
523 		frames_per_packet <<= 8;
524 		frames_per_packet /=
525 			s->cfg.frame_size * inurb->number_of_packets;
526 		frames_per_packet++;
527 
528 		max_diff_0 = s->cfg.frame_size;
529 		if (s->cfg.period_frames >= 256)
530 			max_diff_0 <<= 1;
531 		if (s->cfg.period_frames >= 1024)
532 			max_diff_0 <<= 1;
533 		max_diff = max_diff_0;
534 		for (p = 0; p < inurb->number_of_packets; ++p) {
535 			int diff;
536 			l = inurb->iso_frame_desc[p].actual_length;
537 			urb_size += l;
538 
539 			min_frames += frames_per_packet;
540 			diff = urb_size -
541 				(min_frames >> 8) * s->cfg.frame_size;
542 			if (diff < max_diff) {
543 				snd_printdd(KERN_DEBUG "%i %i %i %i\n",
544 					    s->insize_done,
545 					    urb_size / (int)s->cfg.frame_size,
546 					    inurb->number_of_packets, diff);
547 				max_diff = diff;
548 			}
549 		}
550 		s->idle_insize -= max_diff - max_diff_0;
551 		s->idle_insize += urb_size - s->period_size;
552 		if (s->idle_insize < 0) {
553 			snd_printk(KERN_WARNING "%i %i %i\n",
554 				   s->idle_insize, urb_size, s->period_size);
555 			return;
556 		} else if (s->idle_insize == 0) {
557 			s->next_inpacket_split =
558 				(s->inpacket_head + 1) % s->inpackets;
559 			s->next_inpacket_split_at = 0;
560 		} else {
561 			unsigned split = s->inpacket_head;
562 			l = s->idle_insize;
563 			while (l > s->inpacket[split].length) {
564 				l -= s->inpacket[split].length;
565 				if (split == 0)
566 					split = s->inpackets - 1;
567 				else
568 					split--;
569 			}
570 			s->next_inpacket_split = split;
571 			s->next_inpacket_split_at =
572 				s->inpacket[split].length - l;
573 		}
574 
575 		s->insize_done += urb_size;
576 
577 		if (usb_stream_prepare_playback(sk, inurb) < 0)
578 			return;
579 
580 	} else
581 		playback_prep_freqn(sk, sk->idle_outurb);
582 
583 	if (submit_urbs(sk, inurb, outurb) < 0)
584 		return;
585 
586 	if (s->state == usb_stream_sync1 && s->insize_done > 360000) {
587 		/* just guesswork                            ^^^^^^ */
588 		s->state = usb_stream_ready;
589 		subs_set_complete(sk->inurb, i_capture_idle);
590 		subs_set_complete(sk->outurb, i_playback_idle);
591 	}
592 }
593 
594 static void i_capture_start(struct urb *urb)
595 {
596 	struct usb_iso_packet_descriptor *id = urb->iso_frame_desc;
597 	struct usb_stream_kernel *sk = urb->context;
598 	struct usb_stream *s = sk->s;
599 	int p;
600 	int empty = 0;
601 
602 	if (urb->status) {
603 		snd_printk(KERN_WARNING "status=%i\n", urb->status);
604 		return;
605 	}
606 
607 	for (p = 0; p < urb->number_of_packets; ++p) {
608 		int l = id[p].actual_length;
609 		if (l < s->cfg.frame_size) {
610 			++empty;
611 			if (s->state >= usb_stream_sync0) {
612 				snd_printk(KERN_WARNING "%i\n", l);
613 				return;
614 			}
615 		}
616 		s->inpacket_head++;
617 		s->inpacket_head %= s->inpackets;
618 		s->inpacket[s->inpacket_head].offset =
619 			id[p].offset + (urb->transfer_buffer - (void *)s);
620 		s->inpacket[s->inpacket_head].length = l;
621 	}
622 #ifdef SHOW_EMPTY
623 	if (empty) {
624 		printk(KERN_DEBUG"%s:%i: %i", __func__, __LINE__,
625 		       urb->iso_frame_desc[0].actual_length);
626 		for (pack = 1; pack < urb->number_of_packets; ++pack) {
627 			int l = urb->iso_frame_desc[pack].actual_length;
628 			printk(" %i", l);
629 		}
630 		printk("\n");
631 	}
632 #endif
633 	if (!empty && s->state < usb_stream_sync1)
634 		++s->state;
635 
636 	if (balance_capture(sk, urb))
637 		stream_start(sk, urb, sk->i_urb);
638 }
639 
640 static void i_playback_start(struct urb *urb)
641 {
642 	struct usb_stream_kernel *sk = urb->context;
643 	if (balance_playback(sk, urb))
644 		stream_start(sk, sk->i_urb, urb);
645 }
646 
647 int usb_stream_start(struct usb_stream_kernel *sk)
648 {
649 	struct usb_stream *s = sk->s;
650 	int frame = 0, iters = 0;
651 	int u, err;
652 	int try = 0;
653 
654 	if (s->state != usb_stream_stopped)
655 		return -EAGAIN;
656 
657 	subs_set_complete(sk->inurb, i_capture_start);
658 	subs_set_complete(sk->outurb, i_playback_start);
659 	memset(sk->write_page, 0, s->write_size);
660 dotry:
661 	s->insize_done = 0;
662 	s->idle_insize = 0;
663 	s->idle_outsize = 0;
664 	s->sync_packet = -1;
665 	s->inpacket_head = -1;
666 	sk->iso_frame_balance = 0;
667 	++try;
668 	for (u = 0; u < 2; u++) {
669 		struct urb *inurb = sk->inurb[u];
670 		struct urb *outurb = sk->outurb[u];
671 		playback_prep_freqn(sk, outurb);
672 		inurb->number_of_packets = outurb->number_of_packets;
673 		inurb->transfer_buffer_length =
674 			inurb->number_of_packets *
675 			inurb->iso_frame_desc[0].length;
676 
677 		if (u == 0) {
678 			int now;
679 			struct usb_device *dev = inurb->dev;
680 			frame = usb_get_current_frame_number(dev);
681 			do {
682 				now = usb_get_current_frame_number(dev);
683 				++iters;
684 			} while (now > -1 && now == frame);
685 		}
686 		err = usb_submit_urb(inurb, GFP_ATOMIC);
687 		if (err < 0) {
688 			snd_printk(KERN_ERR"usb_submit_urb(sk->inurb[%i])"
689 				   " returned %i\n", u, err);
690 			return err;
691 		}
692 		err = usb_submit_urb(outurb, GFP_ATOMIC);
693 		if (err < 0) {
694 			snd_printk(KERN_ERR"usb_submit_urb(sk->outurb[%i])"
695 				   " returned %i\n", u, err);
696 			return err;
697 		}
698 
699 		if (inurb->start_frame != outurb->start_frame) {
700 			snd_printd(KERN_DEBUG
701 				   "u[%i] start_frames differ in:%u out:%u\n",
702 				   u, inurb->start_frame, outurb->start_frame);
703 			goto check_retry;
704 		}
705 	}
706 	snd_printdd(KERN_DEBUG "%i %i\n", frame, iters);
707 	try = 0;
708 check_retry:
709 	if (try) {
710 		usb_stream_stop(sk);
711 		if (try < 5) {
712 			msleep(1500);
713 			snd_printd(KERN_DEBUG "goto dotry;\n");
714 			goto dotry;
715 		}
716 		snd_printk(KERN_WARNING"couldn't start"
717 			   " all urbs on the same start_frame.\n");
718 		return -EFAULT;
719 	}
720 
721 	sk->idle_inurb = sk->inurb[USB_STREAM_NURBS - 2];
722 	sk->idle_outurb = sk->outurb[USB_STREAM_NURBS - 2];
723 	sk->completed_inurb = sk->inurb[USB_STREAM_NURBS - 1];
724 	sk->completed_outurb = sk->outurb[USB_STREAM_NURBS - 1];
725 
726 /* wait, check */
727 	{
728 		int wait_ms = 3000;
729 		while (s->state != usb_stream_ready && wait_ms > 0) {
730 			snd_printdd(KERN_DEBUG "%i\n", s->state);
731 			msleep(200);
732 			wait_ms -= 200;
733 		}
734 	}
735 
736 	return s->state == usb_stream_ready ? 0 : -EFAULT;
737 }
738 
739 
740 /*                             stop                                   */
741 
742 void usb_stream_stop(struct usb_stream_kernel *sk)
743 {
744 	int u;
745 	if (!sk->s)
746 		return;
747 	for (u = 0; u < USB_STREAM_NURBS; ++u) {
748 		usb_kill_urb(sk->inurb[u]);
749 		usb_kill_urb(sk->outurb[u]);
750 	}
751 	sk->s->state = usb_stream_stopped;
752 	msleep(400);
753 }
754