xref: /openbmc/linux/sound/usb/usx2y/usb_stream.c (revision 8cb5d748)
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 		goto report_failure;
357 
358 	sk->idle_inurb = sk->completed_inurb;
359 	sk->completed_inurb = inurb;
360 	err = usb_submit_urb(sk->idle_outurb, GFP_ATOMIC);
361 	if (err < 0)
362 		goto report_failure;
363 
364 	sk->idle_outurb = sk->completed_outurb;
365 	sk->completed_outurb = outurb;
366 	return 0;
367 
368 report_failure:
369 	snd_printk(KERN_ERR "%i\n", err);
370 	return err;
371 }
372 
373 #ifdef DEBUG_LOOP_BACK
374 /*
375   This loop_back() shows how to read/write the period data.
376  */
377 static void loop_back(struct usb_stream *s)
378 {
379 	char *i, *o;
380 	int il, ol, l, p;
381 	struct urb *iu;
382 	struct usb_iso_packet_descriptor *id;
383 
384 	o = s->playback1st_to;
385 	ol = s->playback1st_size;
386 	l = 0;
387 
388 	if (s->insplit_pack >= 0) {
389 		iu = sk->idle_inurb;
390 		id = iu->iso_frame_desc;
391 		p = s->insplit_pack;
392 	} else
393 		goto second;
394 loop:
395 	for (; p < iu->number_of_packets && l < s->period_size; ++p) {
396 		i = iu->transfer_buffer + id[p].offset;
397 		il = id[p].actual_length;
398 		if (l + il > s->period_size)
399 			il = s->period_size - l;
400 		if (il <= ol) {
401 			memcpy(o, i, il);
402 			o += il;
403 			ol -= il;
404 		} else {
405 			memcpy(o, i, ol);
406 			singen_6pack(o, ol);
407 			o = s->playback_to;
408 			memcpy(o, i + ol, il - ol);
409 			o += il - ol;
410 			ol = s->period_size - s->playback1st_size;
411 		}
412 		l += il;
413 	}
414 	if (iu == sk->completed_inurb) {
415 		if (l != s->period_size)
416 			printk(KERN_DEBUG"%s:%i %i\n", __func__, __LINE__,
417 			       l/(int)s->cfg.frame_size);
418 
419 		return;
420 	}
421 second:
422 	iu = sk->completed_inurb;
423 	id = iu->iso_frame_desc;
424 	p = 0;
425 	goto loop;
426 
427 }
428 #else
429 static void loop_back(struct usb_stream *s)
430 {
431 }
432 #endif
433 
434 static void stream_idle(struct usb_stream_kernel *sk,
435 			struct urb *inurb, struct urb *outurb)
436 {
437 	struct usb_stream *s = sk->s;
438 	int l, p;
439 	int insize = s->idle_insize;
440 	int urb_size = 0;
441 
442 	s->inpacket_split = s->next_inpacket_split;
443 	s->inpacket_split_at = s->next_inpacket_split_at;
444 	s->next_inpacket_split = -1;
445 	s->next_inpacket_split_at = 0;
446 
447 	for (p = 0; p < inurb->number_of_packets; ++p) {
448 		struct usb_iso_packet_descriptor *id = inurb->iso_frame_desc;
449 		l = id[p].actual_length;
450 		if (unlikely(l == 0 || id[p].status)) {
451 			snd_printk(KERN_WARNING "underrun, status=%u\n",
452 				   id[p].status);
453 			goto err_out;
454 		}
455 		s->inpacket_head++;
456 		s->inpacket_head %= s->inpackets;
457 		if (s->inpacket_split == -1)
458 			s->inpacket_split = s->inpacket_head;
459 
460 		s->inpacket[s->inpacket_head].offset =
461 			id[p].offset + (inurb->transfer_buffer - (void *)s);
462 		s->inpacket[s->inpacket_head].length = l;
463 		if (insize + l > s->period_size &&
464 		    s->next_inpacket_split == -1) {
465 			s->next_inpacket_split = s->inpacket_head;
466 			s->next_inpacket_split_at = s->period_size - insize;
467 		}
468 		insize += l;
469 		urb_size += l;
470 	}
471 	s->idle_insize += urb_size - s->period_size;
472 	if (s->idle_insize < 0) {
473 		snd_printk(KERN_WARNING "%i\n",
474 			   (s->idle_insize)/(int)s->cfg.frame_size);
475 		goto err_out;
476 	}
477 	s->insize_done += urb_size;
478 
479 	l = s->idle_outsize;
480 	s->outpacket[0].offset = (sk->idle_outurb->transfer_buffer -
481 				  sk->write_page) - l;
482 
483 	if (usb_stream_prepare_playback(sk, inurb) < 0)
484 		goto err_out;
485 
486 	s->outpacket[0].length = sk->idle_outurb->transfer_buffer_length + l;
487 	s->outpacket[1].offset = sk->completed_outurb->transfer_buffer -
488 		sk->write_page;
489 
490 	if (submit_urbs(sk, inurb, outurb) < 0)
491 		goto err_out;
492 
493 	loop_back(s);
494 	s->periods_done++;
495 	wake_up_all(&sk->sleep);
496 	return;
497 err_out:
498 	s->state = usb_stream_xrun;
499 	wake_up_all(&sk->sleep);
500 }
501 
502 static void i_capture_idle(struct urb *urb)
503 {
504 	struct usb_stream_kernel *sk = urb->context;
505 	if (balance_capture(sk, urb))
506 		stream_idle(sk, urb, sk->i_urb);
507 }
508 
509 static void i_playback_idle(struct urb *urb)
510 {
511 	struct usb_stream_kernel *sk = urb->context;
512 	if (balance_playback(sk, urb))
513 		stream_idle(sk, sk->i_urb, urb);
514 }
515 
516 static void stream_start(struct usb_stream_kernel *sk,
517 			 struct urb *inurb, struct urb *outurb)
518 {
519 	struct usb_stream *s = sk->s;
520 	if (s->state >= usb_stream_sync1) {
521 		int l, p, max_diff, max_diff_0;
522 		int urb_size = 0;
523 		unsigned frames_per_packet, min_frames = 0;
524 		frames_per_packet = (s->period_size - s->idle_insize);
525 		frames_per_packet <<= 8;
526 		frames_per_packet /=
527 			s->cfg.frame_size * inurb->number_of_packets;
528 		frames_per_packet++;
529 
530 		max_diff_0 = s->cfg.frame_size;
531 		if (s->cfg.period_frames >= 256)
532 			max_diff_0 <<= 1;
533 		if (s->cfg.period_frames >= 1024)
534 			max_diff_0 <<= 1;
535 		max_diff = max_diff_0;
536 		for (p = 0; p < inurb->number_of_packets; ++p) {
537 			int diff;
538 			l = inurb->iso_frame_desc[p].actual_length;
539 			urb_size += l;
540 
541 			min_frames += frames_per_packet;
542 			diff = urb_size -
543 				(min_frames >> 8) * s->cfg.frame_size;
544 			if (diff < max_diff) {
545 				snd_printdd(KERN_DEBUG "%i %i %i %i\n",
546 					    s->insize_done,
547 					    urb_size / (int)s->cfg.frame_size,
548 					    inurb->number_of_packets, diff);
549 				max_diff = diff;
550 			}
551 		}
552 		s->idle_insize -= max_diff - max_diff_0;
553 		s->idle_insize += urb_size - s->period_size;
554 		if (s->idle_insize < 0) {
555 			snd_printk(KERN_WARNING "%i %i %i\n",
556 				   s->idle_insize, urb_size, s->period_size);
557 			return;
558 		} else if (s->idle_insize == 0) {
559 			s->next_inpacket_split =
560 				(s->inpacket_head + 1) % s->inpackets;
561 			s->next_inpacket_split_at = 0;
562 		} else {
563 			unsigned split = s->inpacket_head;
564 			l = s->idle_insize;
565 			while (l > s->inpacket[split].length) {
566 				l -= s->inpacket[split].length;
567 				if (split == 0)
568 					split = s->inpackets - 1;
569 				else
570 					split--;
571 			}
572 			s->next_inpacket_split = split;
573 			s->next_inpacket_split_at =
574 				s->inpacket[split].length - l;
575 		}
576 
577 		s->insize_done += urb_size;
578 
579 		if (usb_stream_prepare_playback(sk, inurb) < 0)
580 			return;
581 
582 	} else
583 		playback_prep_freqn(sk, sk->idle_outurb);
584 
585 	if (submit_urbs(sk, inurb, outurb) < 0)
586 		return;
587 
588 	if (s->state == usb_stream_sync1 && s->insize_done > 360000) {
589 		/* just guesswork                            ^^^^^^ */
590 		s->state = usb_stream_ready;
591 		subs_set_complete(sk->inurb, i_capture_idle);
592 		subs_set_complete(sk->outurb, i_playback_idle);
593 	}
594 }
595 
596 static void i_capture_start(struct urb *urb)
597 {
598 	struct usb_iso_packet_descriptor *id = urb->iso_frame_desc;
599 	struct usb_stream_kernel *sk = urb->context;
600 	struct usb_stream *s = sk->s;
601 	int p;
602 	int empty = 0;
603 
604 	if (urb->status) {
605 		snd_printk(KERN_WARNING "status=%i\n", urb->status);
606 		return;
607 	}
608 
609 	for (p = 0; p < urb->number_of_packets; ++p) {
610 		int l = id[p].actual_length;
611 		if (l < s->cfg.frame_size) {
612 			++empty;
613 			if (s->state >= usb_stream_sync0) {
614 				snd_printk(KERN_WARNING "%i\n", l);
615 				return;
616 			}
617 		}
618 		s->inpacket_head++;
619 		s->inpacket_head %= s->inpackets;
620 		s->inpacket[s->inpacket_head].offset =
621 			id[p].offset + (urb->transfer_buffer - (void *)s);
622 		s->inpacket[s->inpacket_head].length = l;
623 	}
624 #ifdef SHOW_EMPTY
625 	if (empty) {
626 		printk(KERN_DEBUG"%s:%i: %i", __func__, __LINE__,
627 		       urb->iso_frame_desc[0].actual_length);
628 		for (pack = 1; pack < urb->number_of_packets; ++pack) {
629 			int l = urb->iso_frame_desc[pack].actual_length;
630 			printk(KERN_CONT " %i", l);
631 		}
632 		printk(KERN_CONT "\n");
633 	}
634 #endif
635 	if (!empty && s->state < usb_stream_sync1)
636 		++s->state;
637 
638 	if (balance_capture(sk, urb))
639 		stream_start(sk, urb, sk->i_urb);
640 }
641 
642 static void i_playback_start(struct urb *urb)
643 {
644 	struct usb_stream_kernel *sk = urb->context;
645 	if (balance_playback(sk, urb))
646 		stream_start(sk, sk->i_urb, urb);
647 }
648 
649 int usb_stream_start(struct usb_stream_kernel *sk)
650 {
651 	struct usb_stream *s = sk->s;
652 	int frame = 0, iters = 0;
653 	int u, err;
654 	int try = 0;
655 
656 	if (s->state != usb_stream_stopped)
657 		return -EAGAIN;
658 
659 	subs_set_complete(sk->inurb, i_capture_start);
660 	subs_set_complete(sk->outurb, i_playback_start);
661 	memset(sk->write_page, 0, s->write_size);
662 dotry:
663 	s->insize_done = 0;
664 	s->idle_insize = 0;
665 	s->idle_outsize = 0;
666 	s->sync_packet = -1;
667 	s->inpacket_head = -1;
668 	sk->iso_frame_balance = 0;
669 	++try;
670 	for (u = 0; u < 2; u++) {
671 		struct urb *inurb = sk->inurb[u];
672 		struct urb *outurb = sk->outurb[u];
673 		playback_prep_freqn(sk, outurb);
674 		inurb->number_of_packets = outurb->number_of_packets;
675 		inurb->transfer_buffer_length =
676 			inurb->number_of_packets *
677 			inurb->iso_frame_desc[0].length;
678 
679 		if (u == 0) {
680 			int now;
681 			struct usb_device *dev = inurb->dev;
682 			frame = usb_get_current_frame_number(dev);
683 			do {
684 				now = usb_get_current_frame_number(dev);
685 				++iters;
686 			} while (now > -1 && now == frame);
687 		}
688 		err = usb_submit_urb(inurb, GFP_ATOMIC);
689 		if (err < 0) {
690 			snd_printk(KERN_ERR"usb_submit_urb(sk->inurb[%i])"
691 				   " returned %i\n", u, err);
692 			return err;
693 		}
694 		err = usb_submit_urb(outurb, GFP_ATOMIC);
695 		if (err < 0) {
696 			snd_printk(KERN_ERR"usb_submit_urb(sk->outurb[%i])"
697 				   " returned %i\n", u, err);
698 			return err;
699 		}
700 
701 		if (inurb->start_frame != outurb->start_frame) {
702 			snd_printd(KERN_DEBUG
703 				   "u[%i] start_frames differ in:%u out:%u\n",
704 				   u, inurb->start_frame, outurb->start_frame);
705 			goto check_retry;
706 		}
707 	}
708 	snd_printdd(KERN_DEBUG "%i %i\n", frame, iters);
709 	try = 0;
710 check_retry:
711 	if (try) {
712 		usb_stream_stop(sk);
713 		if (try < 5) {
714 			msleep(1500);
715 			snd_printd(KERN_DEBUG "goto dotry;\n");
716 			goto dotry;
717 		}
718 		snd_printk(KERN_WARNING"couldn't start"
719 			   " all urbs on the same start_frame.\n");
720 		return -EFAULT;
721 	}
722 
723 	sk->idle_inurb = sk->inurb[USB_STREAM_NURBS - 2];
724 	sk->idle_outurb = sk->outurb[USB_STREAM_NURBS - 2];
725 	sk->completed_inurb = sk->inurb[USB_STREAM_NURBS - 1];
726 	sk->completed_outurb = sk->outurb[USB_STREAM_NURBS - 1];
727 
728 /* wait, check */
729 	{
730 		int wait_ms = 3000;
731 		while (s->state != usb_stream_ready && wait_ms > 0) {
732 			snd_printdd(KERN_DEBUG "%i\n", s->state);
733 			msleep(200);
734 			wait_ms -= 200;
735 		}
736 	}
737 
738 	return s->state == usb_stream_ready ? 0 : -EFAULT;
739 }
740 
741 
742 /*                             stop                                   */
743 
744 void usb_stream_stop(struct usb_stream_kernel *sk)
745 {
746 	int u;
747 	if (!sk->s)
748 		return;
749 	for (u = 0; u < USB_STREAM_NURBS; ++u) {
750 		usb_kill_urb(sk->inurb[u]);
751 		usb_kill_urb(sk->outurb[u]);
752 	}
753 	sk->s->state = usb_stream_stopped;
754 	msleep(400);
755 }
756