xref: /openbmc/linux/sound/usb/usx2y/usb_stream.c (revision b8bb76713ec50df2f11efee386e16f93d51e1076)
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 
21 #include "usb_stream.h"
22 
23 
24 /*                             setup                                  */
25 
26 static unsigned usb_stream_next_packet_size(struct usb_stream_kernel *sk)
27 {
28 	struct usb_stream *s = sk->s;
29 	sk->out_phase_peeked = (sk->out_phase & 0xffff) + sk->freqn;
30 	return (sk->out_phase_peeked >> 16) * s->cfg.frame_size;
31 }
32 
33 static void playback_prep_freqn(struct usb_stream_kernel *sk, struct urb *urb)
34 {
35 	struct usb_stream *s = sk->s;
36 	unsigned l = 0;
37 	int pack;
38 
39 	urb->iso_frame_desc[0].offset = 0;
40 	urb->iso_frame_desc[0].length =	usb_stream_next_packet_size(sk);
41 	sk->out_phase = sk->out_phase_peeked;
42 	urb->transfer_buffer_length = urb->iso_frame_desc[0].length;
43 
44 	for (pack = 1; pack < sk->n_o_ps; pack++) {
45 		l = usb_stream_next_packet_size(sk);
46 		if (s->idle_outsize + urb->transfer_buffer_length + l >
47 		    s->period_size)
48 			goto check;
49 
50 		sk->out_phase = sk->out_phase_peeked;
51 		urb->iso_frame_desc[pack].offset = urb->transfer_buffer_length;
52 		urb->iso_frame_desc[pack].length = l;
53 		urb->transfer_buffer_length += l;
54 	}
55 	snd_printdd(KERN_DEBUG "%i\n", urb->transfer_buffer_length);
56 
57 check:
58 	urb->number_of_packets = pack;
59 	s->idle_outsize += urb->transfer_buffer_length - s->period_size;
60 	snd_printdd(KERN_DEBUG "idle=%i ul=%i ps=%i\n", s->idle_outsize,
61 		    urb->transfer_buffer_length, s->period_size);
62 }
63 
64 static void init_pipe_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
65 			   struct urb **urbs, char *transfer,
66 			   struct usb_device *dev, int pipe)
67 {
68 	int u, p;
69 	int maxpacket = use_packsize ?
70 		use_packsize : usb_maxpacket(dev, pipe, usb_pipeout(pipe));
71 	int transfer_length = maxpacket * sk->n_o_ps;
72 
73 	for (u = 0; u < USB_STREAM_NURBS;
74 	     ++u, transfer += transfer_length) {
75 		struct urb *urb = urbs[u];
76 		struct usb_iso_packet_descriptor *desc;
77 		urb->transfer_flags = URB_ISO_ASAP;
78 		urb->transfer_buffer = transfer;
79 		urb->dev = dev;
80 		urb->pipe = pipe;
81 		urb->number_of_packets = sk->n_o_ps;
82 		urb->context = sk;
83 		urb->interval = 1;
84 		if (usb_pipeout(pipe))
85 			continue;
86 
87 		urb->transfer_buffer_length = transfer_length;
88 		desc = urb->iso_frame_desc;
89 		desc->offset = 0;
90 		desc->length = maxpacket;
91 		for (p = 1; p < sk->n_o_ps; ++p) {
92 			desc[p].offset = desc[p - 1].offset + maxpacket;
93 			desc[p].length = maxpacket;
94 		}
95 	}
96 }
97 
98 static void init_urbs(struct usb_stream_kernel *sk, unsigned use_packsize,
99 		      struct usb_device *dev, int in_pipe, int out_pipe)
100 {
101 	struct usb_stream	*s = sk->s;
102 	char			*indata = (char *)s + sizeof(*s) +
103 					sizeof(struct usb_stream_packet) *
104 					s->inpackets;
105 	int			u;
106 
107 	for (u = 0; u < USB_STREAM_NURBS; ++u) {
108 		sk->inurb[u] = usb_alloc_urb(sk->n_o_ps, GFP_KERNEL);
109 		sk->outurb[u] = usb_alloc_urb(sk->n_o_ps, GFP_KERNEL);
110 	}
111 
112 	init_pipe_urbs(sk, use_packsize, sk->inurb, indata, dev, in_pipe);
113 	init_pipe_urbs(sk, use_packsize, sk->outurb, sk->write_page, dev,
114 		       out_pipe);
115 }
116 
117 
118 /*
119  * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
120  * this will overflow at approx 524 kHz
121  */
122 static inline unsigned get_usb_full_speed_rate(unsigned rate)
123 {
124 	return ((rate << 13) + 62) / 125;
125 }
126 
127 /*
128  * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
129  * this will overflow at approx 4 MHz
130  */
131 static inline unsigned get_usb_high_speed_rate(unsigned rate)
132 {
133 	return ((rate << 10) + 62) / 125;
134 }
135 
136 void usb_stream_free(struct usb_stream_kernel *sk)
137 {
138 	struct usb_stream *s;
139 	unsigned u;
140 
141 	for (u = 0; u < USB_STREAM_NURBS; ++u) {
142 		usb_free_urb(sk->inurb[u]);
143 		sk->inurb[u] = NULL;
144 		usb_free_urb(sk->outurb[u]);
145 		sk->outurb[u] = NULL;
146 	}
147 
148 	s = sk->s;
149 	if (!s)
150 		return;
151 
152 	free_pages((unsigned long)sk->write_page, get_order(s->write_size));
153 	sk->write_page = NULL;
154 	free_pages((unsigned long)s, get_order(s->read_size));
155 	sk->s = NULL;
156 }
157 
158 struct usb_stream *usb_stream_new(struct usb_stream_kernel *sk,
159 				  struct usb_device *dev,
160 				  unsigned in_endpoint, unsigned out_endpoint,
161 				  unsigned sample_rate, unsigned use_packsize,
162 				  unsigned period_frames, unsigned 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 	int pg;
170 
171 	in_pipe = usb_rcvisocpipe(dev, in_endpoint);
172 	out_pipe = usb_sndisocpipe(dev, out_endpoint);
173 
174 	max_packsize = use_packsize ?
175 		use_packsize : usb_maxpacket(dev, in_pipe, 0);
176 
177 	/*
178 		t_period = period_frames / sample_rate
179 		iso_packs = t_period / t_iso_frame
180 			= (period_frames / sample_rate) * (1 / t_iso_frame)
181 	*/
182 
183 	packets = period_frames * usb_frames / sample_rate + 1;
184 
185 	if (dev->speed == USB_SPEED_HIGH)
186 		packets = (packets + 7) & ~7;
187 
188 	read_size += packets * USB_STREAM_URBDEPTH *
189 		(max_packsize + sizeof(struct usb_stream_packet));
190 
191 	max_packsize = usb_maxpacket(dev, out_pipe, 1);
192 	write_size = max_packsize * packets * USB_STREAM_URBDEPTH;
193 
194 	if (read_size >= 256*PAGE_SIZE || write_size >= 256*PAGE_SIZE) {
195 		snd_printk(KERN_WARNING "a size exceeds 128*PAGE_SIZE\n");
196 		goto out;
197 	}
198 
199 	pg = get_order(read_size);
200 	sk->s = (void *) __get_free_pages(GFP_KERNEL|__GFP_COMP|__GFP_ZERO, pg);
201 	if (!sk->s) {
202 		snd_printk(KERN_WARNING "couldn't __get_free_pages()\n");
203 		goto out;
204 	}
205 	sk->s->cfg.version = USB_STREAM_INTERFACE_VERSION;
206 
207 	sk->s->read_size = read_size;
208 
209 	sk->s->cfg.sample_rate = sample_rate;
210 	sk->s->cfg.frame_size = frame_size;
211 	sk->n_o_ps = packets;
212 	sk->s->inpackets = packets * USB_STREAM_URBDEPTH;
213 	sk->s->cfg.period_frames = period_frames;
214 	sk->s->period_size = frame_size * period_frames;
215 
216 	sk->s->write_size = write_size;
217 	pg = get_order(write_size);
218 
219 	sk->write_page =
220 		(void *)__get_free_pages(GFP_KERNEL|__GFP_COMP|__GFP_ZERO, pg);
221 	if (!sk->write_page) {
222 		snd_printk(KERN_WARNING "couldn't __get_free_pages()\n");
223 		usb_stream_free(sk);
224 		return NULL;
225 	}
226 
227 	/* calculate the frequency in 16.16 format */
228 	if (dev->speed == USB_SPEED_FULL)
229 		sk->freqn = get_usb_full_speed_rate(sample_rate);
230 	else
231 		sk->freqn = get_usb_high_speed_rate(sample_rate);
232 
233 	init_urbs(sk, use_packsize, dev, in_pipe, out_pipe);
234 	sk->s->state = usb_stream_stopped;
235 out:
236 	return sk->s;
237 }
238 
239 
240 /*                             start                                  */
241 
242 static bool balance_check(struct usb_stream_kernel *sk, struct urb *urb)
243 {
244 	bool r;
245 	if (unlikely(urb->status)) {
246 		if (urb->status != -ESHUTDOWN && urb->status != -ENOENT)
247 			snd_printk(KERN_WARNING "status=%i\n", urb->status);
248 		sk->iso_frame_balance = 0x7FFFFFFF;
249 		return false;
250 	}
251 	r = sk->iso_frame_balance == 0;
252 	if (!r)
253 		sk->i_urb = urb;
254 	return r;
255 }
256 
257 static bool balance_playback(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 bool balance_capture(struct usb_stream_kernel *sk, struct urb *urb)
264 {
265 	sk->iso_frame_balance -= urb->number_of_packets;
266 	return balance_check(sk, urb);
267 }
268 
269 static void subs_set_complete(struct urb **urbs, void (*complete)(struct urb *))
270 {
271 	int u;
272 
273 	for (u = 0; u < USB_STREAM_NURBS; u++) {
274 		struct urb *urb = urbs[u];
275 		urb->complete = complete;
276 	}
277 }
278 
279 static int usb_stream_prepare_playback(struct usb_stream_kernel *sk,
280 		struct urb *inurb)
281 {
282 	struct usb_stream *s = sk->s;
283 	struct urb *io;
284 	struct usb_iso_packet_descriptor *id, *od;
285 	int p, l = 0;
286 
287 	io = sk->idle_outurb;
288 	od = io->iso_frame_desc;
289 	io->transfer_buffer_length = 0;
290 
291 	for (p = 0; s->sync_packet < 0; ++p, ++s->sync_packet) {
292 		struct urb *ii = sk->completed_inurb;
293 		id = ii->iso_frame_desc +
294 			ii->number_of_packets + s->sync_packet;
295 		l = id->actual_length;
296 
297 		od[p].length = l;
298 		od[p].offset = io->transfer_buffer_length;
299 		io->transfer_buffer_length += l;
300 	}
301 
302 	for (;
303 	     s->sync_packet < inurb->number_of_packets && p < sk->n_o_ps;
304 	     ++p, ++s->sync_packet) {
305 		l = inurb->iso_frame_desc[s->sync_packet].actual_length;
306 
307 		if (s->idle_outsize + io->transfer_buffer_length + l >
308 		    s->period_size)
309 			goto check_ok;
310 
311 		od[p].length = l;
312 		od[p].offset = io->transfer_buffer_length;
313 		io->transfer_buffer_length += l;
314 	}
315 
316 check_ok:
317 	s->sync_packet -= inurb->number_of_packets;
318 	if (s->sync_packet < -2 || s->sync_packet > 0) {
319 		snd_printk(KERN_WARNING "invalid sync_packet = %i;"
320 			   " p=%i nop=%i %i %x %x %x > %x\n",
321 			   s->sync_packet, p, inurb->number_of_packets,
322 			   s->idle_outsize + io->transfer_buffer_length + l,
323 			   s->idle_outsize, io->transfer_buffer_length,  l,
324 			   s->period_size);
325 		return -1;
326 	}
327 	if (io->transfer_buffer_length % s->cfg.frame_size) {
328 		snd_printk(KERN_WARNING"invalid outsize = %i\n",
329 			   io->transfer_buffer_length);
330 		return -1;
331 	}
332 	s->idle_outsize += io->transfer_buffer_length - s->period_size;
333 	io->number_of_packets = p;
334 	if (s->idle_outsize > 0) {
335 		snd_printk(KERN_WARNING "idle=%i\n", s->idle_outsize);
336 		return -1;
337 	}
338 	return 0;
339 }
340 
341 static void prepare_inurb(int number_of_packets, struct urb *iu)
342 {
343 	struct usb_iso_packet_descriptor *id;
344 	int p;
345 
346 	iu->number_of_packets = number_of_packets;
347 	id = iu->iso_frame_desc;
348 	id->offset = 0;
349 	for (p = 0; p < iu->number_of_packets - 1; ++p)
350 		id[p + 1].offset = id[p].offset + id[p].length;
351 
352 	iu->transfer_buffer_length =
353 		id[0].length * iu->number_of_packets;
354 }
355 
356 static int submit_urbs(struct usb_stream_kernel *sk,
357 		       struct urb *inurb, struct urb *outurb)
358 {
359 	int err;
360 	prepare_inurb(sk->idle_outurb->number_of_packets, sk->idle_inurb);
361 	err = usb_submit_urb(sk->idle_inurb, GFP_ATOMIC);
362 	if (err < 0) {
363 		snd_printk(KERN_ERR "%i\n", err);
364 		return err;
365 	}
366 	sk->idle_inurb = sk->completed_inurb;
367 	sk->completed_inurb = inurb;
368 	err = usb_submit_urb(sk->idle_outurb, GFP_ATOMIC);
369 	if (err < 0) {
370 		snd_printk(KERN_ERR "%i\n", err);
371 		return err;
372 	}
373 	sk->idle_outurb = sk->completed_outurb;
374 	sk->completed_outurb = outurb;
375 	return 0;
376 }
377 
378 #ifdef DEBUG_LOOP_BACK
379 /*
380   This loop_back() shows how to read/write the period data.
381  */
382 static void loop_back(struct usb_stream *s)
383 {
384 	char *i, *o;
385 	int il, ol, l, p;
386 	struct urb *iu;
387 	struct usb_iso_packet_descriptor *id;
388 
389 	o = s->playback1st_to;
390 	ol = s->playback1st_size;
391 	l = 0;
392 
393 	if (s->insplit_pack >= 0) {
394 		iu = sk->idle_inurb;
395 		id = iu->iso_frame_desc;
396 		p = s->insplit_pack;
397 	} else
398 		goto second;
399 loop:
400 	for (; p < iu->number_of_packets && l < s->period_size; ++p) {
401 		i = iu->transfer_buffer + id[p].offset;
402 		il = id[p].actual_length;
403 		if (l + il > s->period_size)
404 			il = s->period_size - l;
405 		if (il <= ol) {
406 			memcpy(o, i, il);
407 			o += il;
408 			ol -= il;
409 		} else {
410 			memcpy(o, i, ol);
411 			singen_6pack(o, ol);
412 			o = s->playback_to;
413 			memcpy(o, i + ol, il - ol);
414 			o += il - ol;
415 			ol = s->period_size - s->playback1st_size;
416 		}
417 		l += il;
418 	}
419 	if (iu == sk->completed_inurb) {
420 		if (l != s->period_size)
421 			printk(KERN_DEBUG"%s:%i %i\n", __func__, __LINE__,
422 			       l/(int)s->cfg.frame_size);
423 
424 		return;
425 	}
426 second:
427 	iu = sk->completed_inurb;
428 	id = iu->iso_frame_desc;
429 	p = 0;
430 	goto loop;
431 
432 }
433 #else
434 static void loop_back(struct usb_stream *s)
435 {
436 }
437 #endif
438 
439 static void stream_idle(struct usb_stream_kernel *sk,
440 			struct urb *inurb, struct urb *outurb)
441 {
442 	struct usb_stream *s = sk->s;
443 	int l, p;
444 	int insize = s->idle_insize;
445 	int urb_size = 0;
446 
447 	s->inpacket_split = s->next_inpacket_split;
448 	s->inpacket_split_at = s->next_inpacket_split_at;
449 	s->next_inpacket_split = -1;
450 	s->next_inpacket_split_at = 0;
451 
452 	for (p = 0; p < inurb->number_of_packets; ++p) {
453 		struct usb_iso_packet_descriptor *id = inurb->iso_frame_desc;
454 		l = id[p].actual_length;
455 		if (unlikely(l == 0 || id[p].status)) {
456 			snd_printk(KERN_WARNING "underrun, status=%u\n",
457 				   id[p].status);
458 			goto err_out;
459 		}
460 		s->inpacket_head++;
461 		s->inpacket_head %= s->inpackets;
462 		if (s->inpacket_split == -1)
463 			s->inpacket_split = s->inpacket_head;
464 
465 		s->inpacket[s->inpacket_head].offset =
466 			id[p].offset + (inurb->transfer_buffer - (void *)s);
467 		s->inpacket[s->inpacket_head].length = l;
468 		if (insize + l > s->period_size &&
469 		    s->next_inpacket_split == -1) {
470 			s->next_inpacket_split = s->inpacket_head;
471 			s->next_inpacket_split_at = s->period_size - insize;
472 		}
473 		insize += l;
474 		urb_size += l;
475 	}
476 	s->idle_insize += urb_size - s->period_size;
477 	if (s->idle_insize < 0) {
478 		snd_printk(KERN_WARNING "%i\n",
479 			   (s->idle_insize)/(int)s->cfg.frame_size);
480 		goto err_out;
481 	}
482 	s->insize_done += urb_size;
483 
484 	l = s->idle_outsize;
485 	s->outpacket[0].offset = (sk->idle_outurb->transfer_buffer -
486 				  sk->write_page) - l;
487 
488 	if (usb_stream_prepare_playback(sk, inurb) < 0)
489 		goto err_out;
490 
491 	s->outpacket[0].length = sk->idle_outurb->transfer_buffer_length + l;
492 	s->outpacket[1].offset = sk->completed_outurb->transfer_buffer -
493 		sk->write_page;
494 
495 	if (submit_urbs(sk, inurb, outurb) < 0)
496 		goto err_out;
497 
498 	loop_back(s);
499 	s->periods_done++;
500 	wake_up_all(&sk->sleep);
501 	return;
502 err_out:
503 	s->state = usb_stream_xrun;
504 	wake_up_all(&sk->sleep);
505 }
506 
507 static void i_capture_idle(struct urb *urb)
508 {
509 	struct usb_stream_kernel *sk = urb->context;
510 	if (balance_capture(sk, urb))
511 		stream_idle(sk, urb, sk->i_urb);
512 }
513 
514 static void i_playback_idle(struct urb *urb)
515 {
516 	struct usb_stream_kernel *sk = urb->context;
517 	if (balance_playback(sk, urb))
518 		stream_idle(sk, sk->i_urb, urb);
519 }
520 
521 static void stream_start(struct usb_stream_kernel *sk,
522 			 struct urb *inurb, struct urb *outurb)
523 {
524 	struct usb_stream *s = sk->s;
525 	if (s->state >= usb_stream_sync1) {
526 		int l, p, max_diff, max_diff_0;
527 		int urb_size = 0;
528 		unsigned frames_per_packet, min_frames = 0;
529 		frames_per_packet = (s->period_size - s->idle_insize);
530 		frames_per_packet <<= 8;
531 		frames_per_packet /=
532 			s->cfg.frame_size * inurb->number_of_packets;
533 		frames_per_packet++;
534 
535 		max_diff_0 = s->cfg.frame_size;
536 		if (s->cfg.period_frames >= 256)
537 			max_diff_0 <<= 1;
538 		if (s->cfg.period_frames >= 1024)
539 			max_diff_0 <<= 1;
540 		max_diff = max_diff_0;
541 		for (p = 0; p < inurb->number_of_packets; ++p) {
542 			int diff;
543 			l = inurb->iso_frame_desc[p].actual_length;
544 			urb_size += l;
545 
546 			min_frames += frames_per_packet;
547 			diff = urb_size -
548 				(min_frames >> 8) * s->cfg.frame_size;
549 			if (diff < max_diff) {
550 				snd_printdd(KERN_DEBUG "%i %i %i %i\n",
551 					    s->insize_done,
552 					    urb_size / (int)s->cfg.frame_size,
553 					    inurb->number_of_packets, diff);
554 				max_diff = diff;
555 			}
556 		}
557 		s->idle_insize -= max_diff - max_diff_0;
558 		s->idle_insize += urb_size - s->period_size;
559 		if (s->idle_insize < 0) {
560 			snd_printk(KERN_WARNING "%i %i %i\n",
561 				   s->idle_insize, urb_size, s->period_size);
562 			return;
563 		} else if (s->idle_insize == 0) {
564 			s->next_inpacket_split =
565 				(s->inpacket_head + 1) % s->inpackets;
566 			s->next_inpacket_split_at = 0;
567 		} else {
568 			unsigned split = s->inpacket_head;
569 			l = s->idle_insize;
570 			while (l > s->inpacket[split].length) {
571 				l -= s->inpacket[split].length;
572 				if (split == 0)
573 					split = s->inpackets - 1;
574 				else
575 					split--;
576 			}
577 			s->next_inpacket_split = split;
578 			s->next_inpacket_split_at =
579 				s->inpacket[split].length - l;
580 		}
581 
582 		s->insize_done += urb_size;
583 
584 		if (usb_stream_prepare_playback(sk, inurb) < 0)
585 			return;
586 
587 	} else
588 		playback_prep_freqn(sk, sk->idle_outurb);
589 
590 	if (submit_urbs(sk, inurb, outurb) < 0)
591 		return;
592 
593 	if (s->state == usb_stream_sync1 && s->insize_done > 360000) {
594 		/* just guesswork                            ^^^^^^ */
595 		s->state = usb_stream_ready;
596 		subs_set_complete(sk->inurb, i_capture_idle);
597 		subs_set_complete(sk->outurb, i_playback_idle);
598 	}
599 }
600 
601 static void i_capture_start(struct urb *urb)
602 {
603 	struct usb_iso_packet_descriptor *id = urb->iso_frame_desc;
604 	struct usb_stream_kernel *sk = urb->context;
605 	struct usb_stream *s = sk->s;
606 	int p;
607 	int empty = 0;
608 
609 	if (urb->status) {
610 		snd_printk(KERN_WARNING "status=%i\n", urb->status);
611 		return;
612 	}
613 
614 	for (p = 0; p < urb->number_of_packets; ++p) {
615 		int l = id[p].actual_length;
616 		if (l < s->cfg.frame_size) {
617 			++empty;
618 			if (s->state >= usb_stream_sync0) {
619 				snd_printk(KERN_WARNING "%i\n", l);
620 				return;
621 			}
622 		}
623 		s->inpacket_head++;
624 		s->inpacket_head %= s->inpackets;
625 		s->inpacket[s->inpacket_head].offset =
626 			id[p].offset + (urb->transfer_buffer - (void *)s);
627 		s->inpacket[s->inpacket_head].length = l;
628 	}
629 #ifdef SHOW_EMPTY
630 	if (empty) {
631 		printk(KERN_DEBUG"%s:%i: %i", __func__, __LINE__,
632 		       urb->iso_frame_desc[0].actual_length);
633 		for (pack = 1; pack < urb->number_of_packets; ++pack) {
634 			int l = urb->iso_frame_desc[pack].actual_length;
635 			printk(" %i", l);
636 		}
637 		printk("\n");
638 	}
639 #endif
640 	if (!empty && s->state < usb_stream_sync1)
641 		++s->state;
642 
643 	if (balance_capture(sk, urb))
644 		stream_start(sk, urb, sk->i_urb);
645 }
646 
647 static void i_playback_start(struct urb *urb)
648 {
649 	struct usb_stream_kernel *sk = urb->context;
650 	if (balance_playback(sk, urb))
651 		stream_start(sk, sk->i_urb, urb);
652 }
653 
654 int usb_stream_start(struct usb_stream_kernel *sk)
655 {
656 	struct usb_stream *s = sk->s;
657 	int frame = 0, iters = 0;
658 	int u, err;
659 	int try = 0;
660 
661 	if (s->state != usb_stream_stopped)
662 		return -EAGAIN;
663 
664 	subs_set_complete(sk->inurb, i_capture_start);
665 	subs_set_complete(sk->outurb, i_playback_start);
666 	memset(sk->write_page, 0, s->write_size);
667 dotry:
668 	s->insize_done = 0;
669 	s->idle_insize = 0;
670 	s->idle_outsize = 0;
671 	s->sync_packet = -1;
672 	s->inpacket_head = -1;
673 	sk->iso_frame_balance = 0;
674 	++try;
675 	for (u = 0; u < 2; u++) {
676 		struct urb *inurb = sk->inurb[u];
677 		struct urb *outurb = sk->outurb[u];
678 		playback_prep_freqn(sk, outurb);
679 		inurb->number_of_packets = outurb->number_of_packets;
680 		inurb->transfer_buffer_length =
681 			inurb->number_of_packets *
682 			inurb->iso_frame_desc[0].length;
683 		preempt_disable();
684 		if (u == 0) {
685 			int now;
686 			struct usb_device *dev = inurb->dev;
687 			frame = usb_get_current_frame_number(dev);
688 			do {
689 				now = usb_get_current_frame_number(dev);
690 				++iters;
691 			} while (now > -1 && now == frame);
692 		}
693 		err = usb_submit_urb(inurb, GFP_ATOMIC);
694 		if (err < 0) {
695 			preempt_enable();
696 			snd_printk(KERN_ERR"usb_submit_urb(sk->inurb[%i])"
697 				   " returned %i\n", u, err);
698 			return err;
699 		}
700 		err = usb_submit_urb(outurb, GFP_ATOMIC);
701 		if (err < 0) {
702 			preempt_enable();
703 			snd_printk(KERN_ERR"usb_submit_urb(sk->outurb[%i])"
704 				   " returned %i\n", u, err);
705 			return err;
706 		}
707 		preempt_enable();
708 		if (inurb->start_frame != outurb->start_frame) {
709 			snd_printd(KERN_DEBUG
710 				   "u[%i] start_frames differ in:%u out:%u\n",
711 				   u, inurb->start_frame, outurb->start_frame);
712 			goto check_retry;
713 		}
714 	}
715 	snd_printdd(KERN_DEBUG "%i %i\n", frame, iters);
716 	try = 0;
717 check_retry:
718 	if (try) {
719 		usb_stream_stop(sk);
720 		if (try < 5) {
721 			msleep(1500);
722 			snd_printd(KERN_DEBUG "goto dotry;\n");
723 			goto dotry;
724 		}
725 		snd_printk(KERN_WARNING"couldn't start"
726 			   " all urbs on the same start_frame.\n");
727 		return -EFAULT;
728 	}
729 
730 	sk->idle_inurb = sk->inurb[USB_STREAM_NURBS - 2];
731 	sk->idle_outurb = sk->outurb[USB_STREAM_NURBS - 2];
732 	sk->completed_inurb = sk->inurb[USB_STREAM_NURBS - 1];
733 	sk->completed_outurb = sk->outurb[USB_STREAM_NURBS - 1];
734 
735 /* wait, check */
736 	{
737 		int wait_ms = 3000;
738 		while (s->state != usb_stream_ready && wait_ms > 0) {
739 			snd_printdd(KERN_DEBUG "%i\n", s->state);
740 			msleep(200);
741 			wait_ms -= 200;
742 		}
743 	}
744 
745 	return s->state == usb_stream_ready ? 0 : -EFAULT;
746 }
747 
748 
749 /*                             stop                                   */
750 
751 void usb_stream_stop(struct usb_stream_kernel *sk)
752 {
753 	int u;
754 	if (!sk->s)
755 		return;
756 	for (u = 0; u < USB_STREAM_NURBS; ++u) {
757 		usb_kill_urb(sk->inurb[u]);
758 		usb_kill_urb(sk->outurb[u]);
759 	}
760 	sk->s->state = usb_stream_stopped;
761 	msleep(400);
762 }
763