Linux Audio

Check our new training course

Embedded Linux Audio

Check our new training course
with Creative Commons CC-BY-SA
lecture materials

Bootlin logo

Elixir Cross Referencer

Loading...
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
// SPDX-License-Identifier: GPL-2.0-only
/*
 * bebob_stream.c - a part of driver for BeBoB based devices
 *
 * Copyright (c) 2013-2014 Takashi Sakamoto
 */

#include "./bebob.h"

#define READY_TIMEOUT_MS	4000

/*
 * NOTE;
 * For BeBoB streams, Both of input and output CMP connection are important.
 *
 * For most devices, each CMP connection starts to transmit/receive a
 * corresponding stream. But for a few devices, both of CMP connection needs
 * to start transmitting stream. An example is 'M-Audio Firewire 410'.
 */

/* 128 is an arbitrary length but it seems to be enough */
#define FORMAT_MAXIMUM_LENGTH 128

const unsigned int snd_bebob_rate_table[SND_BEBOB_STRM_FMT_ENTRIES] = {
	[0] = 32000,
	[1] = 44100,
	[2] = 48000,
	[3] = 88200,
	[4] = 96000,
	[5] = 176400,
	[6] = 192000,
};

/*
 * See: Table 51: Extended Stream Format Info ‘Sampling Frequency’
 * in Additional AVC commands (Nov 2003, BridgeCo)
 */
static const unsigned int bridgeco_freq_table[] = {
	[0] = 0x02,
	[1] = 0x03,
	[2] = 0x04,
	[3] = 0x0a,
	[4] = 0x05,
	[5] = 0x06,
	[6] = 0x07,
};

static int
get_formation_index(unsigned int rate, unsigned int *index)
{
	unsigned int i;

	for (i = 0; i < ARRAY_SIZE(snd_bebob_rate_table); i++) {
		if (snd_bebob_rate_table[i] == rate) {
			*index = i;
			return 0;
		}
	}
	return -EINVAL;
}

int
snd_bebob_stream_get_rate(struct snd_bebob *bebob, unsigned int *curr_rate)
{
	unsigned int tx_rate, rx_rate, trials;
	int err;

	trials = 0;
	do {
		err = avc_general_get_sig_fmt(bebob->unit, &tx_rate,
					      AVC_GENERAL_PLUG_DIR_OUT, 0);
	} while (err == -EAGAIN && ++trials < 3);
	if (err < 0)
		goto end;

	trials = 0;
	do {
		err = avc_general_get_sig_fmt(bebob->unit, &rx_rate,
					      AVC_GENERAL_PLUG_DIR_IN, 0);
	} while (err == -EAGAIN && ++trials < 3);
	if (err < 0)
		goto end;

	*curr_rate = rx_rate;
	if (rx_rate == tx_rate)
		goto end;

	/* synchronize receive stream rate to transmit stream rate */
	err = avc_general_set_sig_fmt(bebob->unit, rx_rate,
				      AVC_GENERAL_PLUG_DIR_IN, 0);
end:
	return err;
}

int
snd_bebob_stream_set_rate(struct snd_bebob *bebob, unsigned int rate)
{
	int err;

	err = avc_general_set_sig_fmt(bebob->unit, rate,
				      AVC_GENERAL_PLUG_DIR_OUT, 0);
	if (err < 0)
		goto end;

	err = avc_general_set_sig_fmt(bebob->unit, rate,
				      AVC_GENERAL_PLUG_DIR_IN, 0);
	if (err < 0)
		goto end;

	/*
	 * Some devices need a bit time for transition.
	 * 300msec is got by some experiments.
	 */
	msleep(300);
end:
	return err;
}

int snd_bebob_stream_get_clock_src(struct snd_bebob *bebob,
				   enum snd_bebob_clock_type *src)
{
	const struct snd_bebob_clock_spec *clk_spec = bebob->spec->clock;
	u8 addr[AVC_BRIDGECO_ADDR_BYTES], input[7];
	unsigned int id;
	enum avc_bridgeco_plug_type type;
	int err = 0;

	/* 1.The device has its own operation to switch source of clock */
	if (clk_spec) {
		err = clk_spec->get(bebob, &id);
		if (err < 0) {
			dev_err(&bebob->unit->device,
				"fail to get clock source: %d\n", err);
			goto end;
		}

		if (id >= clk_spec->num) {
			dev_err(&bebob->unit->device,
				"clock source %d out of range 0..%d\n",
				id, clk_spec->num - 1);
			err = -EIO;
			goto end;
		}

		*src = clk_spec->types[id];
		goto end;
	}

	/*
	 * 2.The device don't support to switch source of clock then assumed
	 *   to use internal clock always
	 */
	if (bebob->sync_input_plug < 0) {
		*src = SND_BEBOB_CLOCK_TYPE_INTERNAL;
		goto end;
	}

	/*
	 * 3.The device supports to switch source of clock by an usual way.
	 *   Let's check input for 'Music Sub Unit Sync Input' plug.
	 */
	avc_bridgeco_fill_msu_addr(addr, AVC_BRIDGECO_PLUG_DIR_IN,
				   bebob->sync_input_plug);
	err = avc_bridgeco_get_plug_input(bebob->unit, addr, input);
	if (err < 0) {
		dev_err(&bebob->unit->device,
			"fail to get an input for MSU in plug %d: %d\n",
			bebob->sync_input_plug, err);
		goto end;
	}

	/*
	 * If there are no input plugs, all of fields are 0xff.
	 * Here check the first field. This field is used for direction.
	 */
	if (input[0] == 0xff) {
		*src = SND_BEBOB_CLOCK_TYPE_INTERNAL;
		goto end;
	}

	/* The source from any output plugs is for one purpose only. */
	if (input[0] == AVC_BRIDGECO_PLUG_DIR_OUT) {
		/*
		 * In BeBoB architecture, the source from music subunit may
		 * bypass from oPCR[0]. This means that this source gives
		 * synchronization to IEEE 1394 cycle start packet.
		 */
		if (input[1] == AVC_BRIDGECO_PLUG_MODE_SUBUNIT &&
		    input[2] == 0x0c) {
			*src = SND_BEBOB_CLOCK_TYPE_INTERNAL;
			goto end;
		}
	/* The source from any input units is for several purposes. */
	} else if (input[1] == AVC_BRIDGECO_PLUG_MODE_UNIT) {
		if (input[2] == AVC_BRIDGECO_PLUG_UNIT_ISOC) {
			if (input[3] == 0x00) {
				/*
				 * This source comes from iPCR[0]. This means
				 * that presentation timestamp calculated by
				 * SYT series of the received packets. In
				 * short, this driver is the master of
				 * synchronization.
				 */
				*src = SND_BEBOB_CLOCK_TYPE_SYT;
				goto end;
			} else {
				/*
				 * This source comes from iPCR[1-29]. This
				 * means that the synchronization stream is not
				 * the Audio/MIDI compound stream.
				 */
				*src = SND_BEBOB_CLOCK_TYPE_EXTERNAL;
				goto end;
			}
		} else if (input[2] == AVC_BRIDGECO_PLUG_UNIT_EXT) {
			/* Check type of this plug.  */
			avc_bridgeco_fill_unit_addr(addr,
						    AVC_BRIDGECO_PLUG_DIR_IN,
						    AVC_BRIDGECO_PLUG_UNIT_EXT,
						    input[3]);
			err = avc_bridgeco_get_plug_type(bebob->unit, addr,
							 &type);
			if (err < 0)
				goto end;

			if (type == AVC_BRIDGECO_PLUG_TYPE_DIG) {
				/*
				 * SPDIF/ADAT or sometimes (not always) word
				 * clock.
				 */
				*src = SND_BEBOB_CLOCK_TYPE_EXTERNAL;
				goto end;
			} else if (type == AVC_BRIDGECO_PLUG_TYPE_SYNC) {
				/* Often word clock. */
				*src = SND_BEBOB_CLOCK_TYPE_EXTERNAL;
				goto end;
			} else if (type == AVC_BRIDGECO_PLUG_TYPE_ADDITION) {
				/*
				 * Not standard.
				 * Mostly, additional internal clock.
				 */
				*src = SND_BEBOB_CLOCK_TYPE_INTERNAL;
				goto end;
			}
		}
	}

	/* Not supported. */
	err = -EIO;
end:
	return err;
}

static int map_data_channels(struct snd_bebob *bebob, struct amdtp_stream *s)
{
	unsigned int sec, sections, ch, channels;
	unsigned int pcm, midi, location;
	unsigned int stm_pos, sec_loc, pos;
	u8 *buf, addr[AVC_BRIDGECO_ADDR_BYTES], type;
	enum avc_bridgeco_plug_dir dir;
	int err;

	/*
	 * The length of return value of this command cannot be expected. Here
	 * use the maximum length of FCP.
	 */
	buf = kzalloc(256, GFP_KERNEL);
	if (buf == NULL)
		return -ENOMEM;

	if (s == &bebob->tx_stream)
		dir = AVC_BRIDGECO_PLUG_DIR_OUT;
	else
		dir = AVC_BRIDGECO_PLUG_DIR_IN;

	avc_bridgeco_fill_unit_addr(addr, dir, AVC_BRIDGECO_PLUG_UNIT_ISOC, 0);
	err = avc_bridgeco_get_plug_ch_pos(bebob->unit, addr, buf, 256);
	if (err < 0) {
		dev_err(&bebob->unit->device,
			"fail to get channel position for isoc %s plug 0: %d\n",
			(dir == AVC_BRIDGECO_PLUG_DIR_IN) ? "in" : "out",
			err);
		goto end;
	}
	pos = 0;

	/* positions in I/O buffer */
	pcm = 0;
	midi = 0;

	/* the number of sections in AMDTP packet */
	sections = buf[pos++];

	for (sec = 0; sec < sections; sec++) {
		/* type of this section */
		avc_bridgeco_fill_unit_addr(addr, dir,
					    AVC_BRIDGECO_PLUG_UNIT_ISOC, 0);
		err = avc_bridgeco_get_plug_section_type(bebob->unit, addr,
							 sec, &type);
		if (err < 0) {
			dev_err(&bebob->unit->device,
			"fail to get section type for isoc %s plug 0: %d\n",
				(dir == AVC_BRIDGECO_PLUG_DIR_IN) ? "in" :
								    "out",
				err);
			goto end;
		}
		/* NoType */
		if (type == 0xff) {
			err = -ENOSYS;
			goto end;
		}

		/* the number of channels in this section */
		channels = buf[pos++];

		for (ch = 0; ch < channels; ch++) {
			/* position of this channel in AMDTP packet */
			stm_pos = buf[pos++] - 1;
			/* location of this channel in this section */
			sec_loc = buf[pos++] - 1;

			/*
			 * Basically the number of location is within the
			 * number of channels in this section. But some models
			 * of M-Audio don't follow this. Its location for MIDI
			 * is the position of MIDI channels in AMDTP packet.
			 */
			if (sec_loc >= channels)
				sec_loc = ch;

			switch (type) {
			/* for MIDI conformant data channel */
			case 0x0a:
				/* AMDTP_MAX_CHANNELS_FOR_MIDI is 1. */
				if ((midi > 0) && (stm_pos != midi)) {
					err = -ENOSYS;
					goto end;
				}
				amdtp_am824_set_midi_position(s, stm_pos);
				midi = stm_pos;
				break;
			/* for PCM data channel */
			case 0x01:	/* Headphone */
			case 0x02:	/* Microphone */
			case 0x03:	/* Line */
			case 0x04:	/* SPDIF */
			case 0x05:	/* ADAT */
			case 0x06:	/* TDIF */
			case 0x07:	/* MADI */
			/* for undefined/changeable signal  */
			case 0x08:	/* Analog */
			case 0x09:	/* Digital */
			default:
				location = pcm + sec_loc;
				if (location >= AM824_MAX_CHANNELS_FOR_PCM) {
					err = -ENOSYS;
					goto end;
				}
				amdtp_am824_set_pcm_position(s, location,
							     stm_pos);
				break;
			}
		}

		if (type != 0x0a)
			pcm += channels;
		else
			midi += channels;
	}
end:
	kfree(buf);
	return err;
}

static int
check_connection_used_by_others(struct snd_bebob *bebob, struct amdtp_stream *s)
{
	struct cmp_connection *conn;
	bool used;
	int err;

	if (s == &bebob->tx_stream)
		conn = &bebob->out_conn;
	else
		conn = &bebob->in_conn;

	err = cmp_connection_check_used(conn, &used);
	if ((err >= 0) && used && !amdtp_stream_running(s)) {
		dev_err(&bebob->unit->device,
			"Connection established by others: %cPCR[%d]\n",
			(conn->direction == CMP_OUTPUT) ? 'o' : 'i',
			conn->pcr_index);
		err = -EBUSY;
	}

	return err;
}

static void break_both_connections(struct snd_bebob *bebob)
{
	cmp_connection_break(&bebob->in_conn);
	cmp_connection_break(&bebob->out_conn);
}

static int start_stream(struct snd_bebob *bebob, struct amdtp_stream *stream)
{
	struct cmp_connection *conn;
	int err = 0;

	if (stream == &bebob->rx_stream)
		conn = &bebob->in_conn;
	else
		conn = &bebob->out_conn;

	// channel mapping.
	if (bebob->maudio_special_quirk == NULL) {
		err = map_data_channels(bebob, stream);
		if (err < 0)
			return err;
	}

	err = cmp_connection_establish(conn);
	if (err < 0)
		return err;

	return amdtp_domain_add_stream(&bebob->domain, stream,
				       conn->resources.channel, conn->speed);
}

static int init_stream(struct snd_bebob *bebob, struct amdtp_stream *stream)
{
	unsigned int flags = CIP_BLOCKING;
	enum amdtp_stream_direction dir_stream;
	struct cmp_connection *conn;
	enum cmp_direction dir_conn;
	int err;

	if (stream == &bebob->tx_stream) {
		dir_stream = AMDTP_IN_STREAM;
		conn = &bebob->out_conn;
		dir_conn = CMP_OUTPUT;
	} else {
		dir_stream = AMDTP_OUT_STREAM;
		conn = &bebob->in_conn;
		dir_conn = CMP_INPUT;
	}

	if (stream == &bebob->tx_stream) {
		if (bebob->quirks & SND_BEBOB_QUIRK_WRONG_DBC)
			flags |= CIP_EMPTY_HAS_WRONG_DBC;
	}

	err = cmp_connection_init(conn, bebob->unit, dir_conn, 0);
	if (err < 0)
		return err;

	err = amdtp_am824_init(stream, bebob->unit, dir_stream, flags);
	if (err < 0) {
		cmp_connection_destroy(conn);
		return err;
	}

	return 0;
}

static void destroy_stream(struct snd_bebob *bebob, struct amdtp_stream *stream)
{
	amdtp_stream_destroy(stream);

	if (stream == &bebob->tx_stream)
		cmp_connection_destroy(&bebob->out_conn);
	else
		cmp_connection_destroy(&bebob->in_conn);
}

int snd_bebob_stream_init_duplex(struct snd_bebob *bebob)
{
	int err;

	err = init_stream(bebob, &bebob->tx_stream);
	if (err < 0)
		return err;

	err = init_stream(bebob, &bebob->rx_stream);
	if (err < 0) {
		destroy_stream(bebob, &bebob->tx_stream);
		return err;
	}

	err = amdtp_domain_init(&bebob->domain);
	if (err < 0) {
		destroy_stream(bebob, &bebob->tx_stream);
		destroy_stream(bebob, &bebob->rx_stream);
	}

	return err;
}

static int keep_resources(struct snd_bebob *bebob, struct amdtp_stream *stream,
			  unsigned int rate, unsigned int index)
{
	unsigned int pcm_channels;
	unsigned int midi_ports;
	struct cmp_connection *conn;
	int err;

	if (stream == &bebob->tx_stream) {
		pcm_channels = bebob->tx_stream_formations[index].pcm;
		midi_ports = bebob->midi_input_ports;
		conn = &bebob->out_conn;
	} else {
		pcm_channels = bebob->rx_stream_formations[index].pcm;
		midi_ports = bebob->midi_output_ports;
		conn = &bebob->in_conn;
	}

	err = amdtp_am824_set_parameters(stream, rate, pcm_channels, midi_ports, false);
	if (err < 0)
		return err;

	return cmp_connection_reserve(conn, amdtp_stream_get_max_payload(stream));
}

int snd_bebob_stream_reserve_duplex(struct snd_bebob *bebob, unsigned int rate,
				    unsigned int frames_per_period,
				    unsigned int frames_per_buffer)
{
	unsigned int curr_rate;
	int err;

	// Considering JACK/FFADO streaming:
	// TODO: This can be removed hwdep functionality becomes popular.
	err = check_connection_used_by_others(bebob, &bebob->rx_stream);
	if (err < 0)
		return err;

	err = bebob->spec->rate->get(bebob, &curr_rate);
	if (err < 0)
		return err;
	if (rate == 0)
		rate = curr_rate;
	if (curr_rate != rate) {
		amdtp_domain_stop(&bebob->domain);
		break_both_connections(bebob);

		cmp_connection_release(&bebob->out_conn);
		cmp_connection_release(&bebob->in_conn);
	}

	if (bebob->substreams_counter == 0 || curr_rate != rate) {
		unsigned int index;

		// NOTE:
		// If establishing connections at first, Yamaha GO46
		// (and maybe Terratec X24) don't generate sound.
		//
		// For firmware customized by M-Audio, refer to next NOTE.
		err = bebob->spec->rate->set(bebob, rate);
		if (err < 0) {
			dev_err(&bebob->unit->device,
				"fail to set sampling rate: %d\n",
				err);
			return err;
		}

		err = get_formation_index(rate, &index);
		if (err < 0)
			return err;

		err = keep_resources(bebob, &bebob->tx_stream, rate, index);
		if (err < 0)
			return err;

		err = keep_resources(bebob, &bebob->rx_stream, rate, index);
		if (err < 0) {
			cmp_connection_release(&bebob->out_conn);
			return err;
		}

		err = amdtp_domain_set_events_per_period(&bebob->domain,
					frames_per_period, frames_per_buffer);
		if (err < 0) {
			cmp_connection_release(&bebob->out_conn);
			cmp_connection_release(&bebob->in_conn);
			return err;
		}
	}

	return 0;
}

int snd_bebob_stream_start_duplex(struct snd_bebob *bebob)
{
	int err;

	// Need no substreams.
	if (bebob->substreams_counter == 0)
		return -EIO;

	// packet queueing error or detecting discontinuity
	if (amdtp_streaming_error(&bebob->rx_stream) ||
	    amdtp_streaming_error(&bebob->tx_stream)) {
		amdtp_domain_stop(&bebob->domain);
		break_both_connections(bebob);
	}

	if (!amdtp_stream_running(&bebob->rx_stream)) {
		enum snd_bebob_clock_type src;
		unsigned int curr_rate;
		unsigned int tx_init_skip_cycles;

		if (bebob->maudio_special_quirk) {
			err = bebob->spec->rate->get(bebob, &curr_rate);
			if (err < 0)
				return err;
		}

		err = snd_bebob_stream_get_clock_src(bebob, &src);
		if (err < 0)
			return err;

		err = start_stream(bebob, &bebob->rx_stream);
		if (err < 0)
			goto error;

		err = start_stream(bebob, &bebob->tx_stream);
		if (err < 0)
			goto error;

		if (!(bebob->quirks & SND_BEBOB_QUIRK_INITIAL_DISCONTINUOUS_DBC))
			tx_init_skip_cycles = 0;
		else
			tx_init_skip_cycles = 16000;

		// MEMO: Some devices start packet transmission long enough after establishment of
		// CMP connection. In the early stage of packet streaming, any device transfers
		// NODATA packets. After several hundred cycles, it begins to multiplex event into
		// the packet with adequate value of syt field in CIP header. Some devices are
		// strictly to generate any discontinuity in the sequence of tx packet when they
		// receives inadequate sequence of value in syt field of CIP header. In the case,
		// the request to break CMP connection is often corrupted, then any transaction
		// results in unrecoverable error, sometimes generate bus-reset.
		err = amdtp_domain_start(&bebob->domain, tx_init_skip_cycles, true, false);
		if (err < 0)
			goto error;

		// NOTE:
		// The firmware customized by M-Audio uses these commands to
		// start transmitting stream. This is not usual way.
		if (bebob->maudio_special_quirk) {
			err = bebob->spec->rate->set(bebob, curr_rate);
			if (err < 0) {
				dev_err(&bebob->unit->device,
					"fail to ensure sampling rate: %d\n",
					err);
				goto error;
			}
		}

		// Some devices postpone start of transmission mostly for 1 sec after receives
		// packets firstly.
		if (!amdtp_domain_wait_ready(&bebob->domain, READY_TIMEOUT_MS)) {
			err = -ETIMEDOUT;
			goto error;
		}
	}

	return 0;
error:
	amdtp_domain_stop(&bebob->domain);
	break_both_connections(bebob);
	return err;
}

void snd_bebob_stream_stop_duplex(struct snd_bebob *bebob)
{
	if (bebob->substreams_counter == 0) {
		amdtp_domain_stop(&bebob->domain);
		break_both_connections(bebob);

		cmp_connection_release(&bebob->out_conn);
		cmp_connection_release(&bebob->in_conn);
	}
}

/*
 * This function should be called before starting streams or after stopping
 * streams.
 */
void snd_bebob_stream_destroy_duplex(struct snd_bebob *bebob)
{
	amdtp_domain_destroy(&bebob->domain);

	destroy_stream(bebob, &bebob->tx_stream);
	destroy_stream(bebob, &bebob->rx_stream);
}

/*
 * See: Table 50: Extended Stream Format Info Format Hierarchy Level 2’
 * in Additional AVC commands (Nov 2003, BridgeCo)
 * Also 'Clause 12 AM824 sequence adaption layers' in IEC 61883-6:2005
 */
static int
parse_stream_formation(u8 *buf, unsigned int len,
		       struct snd_bebob_stream_formation *formation)
{
	unsigned int i, e, channels, format;

	/*
	 * this module can support a hierarchy combination that:
	 *  Root:	Audio and Music (0x90)
	 *  Level 1:	AM824 Compound  (0x40)
	 */
	if ((buf[0] != 0x90) || (buf[1] != 0x40))
		return -ENOSYS;

	/* check sampling rate */
	for (i = 0; i < ARRAY_SIZE(bridgeco_freq_table); i++) {
		if (buf[2] == bridgeco_freq_table[i])
			break;
	}
	if (i == ARRAY_SIZE(bridgeco_freq_table))
		return -ENOSYS;

	/* Avoid double count by different entries for the same rate. */
	memset(&formation[i], 0, sizeof(struct snd_bebob_stream_formation));

	for (e = 0; e < buf[4]; e++) {
		channels = buf[5 + e * 2];
		format = buf[6 + e * 2];

		switch (format) {
		/* IEC 60958 Conformant, currently handled as MBLA */
		case 0x00:
		/* Multi bit linear audio */
		case 0x06:	/* Raw */
			formation[i].pcm += channels;
			break;
		/* MIDI Conformant */
		case 0x0d:
			formation[i].midi += channels;
			break;
		/* IEC 61937-3 to 7 */
		case 0x01:
		case 0x02:
		case 0x03:
		case 0x04:
		case 0x05:
		/* Multi bit linear audio */
		case 0x07:	/* DVD-Audio */
		case 0x0c:	/* High Precision */
		/* One Bit Audio */
		case 0x08:	/* (Plain) Raw */
		case 0x09:	/* (Plain) SACD */
		case 0x0a:	/* (Encoded) Raw */
		case 0x0b:	/* (Encoded) SACD */
		/* Synchronization Stream (Stereo Raw audio) */
		case 0x40:
		/* Don't care */
		case 0xff:
		default:
			return -ENOSYS;	/* not supported */
		}
	}

	if (formation[i].pcm  > AM824_MAX_CHANNELS_FOR_PCM ||
	    formation[i].midi > AM824_MAX_CHANNELS_FOR_MIDI)
		return -ENOSYS;

	return 0;
}

static int fill_stream_formations(struct snd_bebob *bebob, u8 addr[AVC_BRIDGECO_ADDR_BYTES],
				  enum avc_bridgeco_plug_dir plug_dir, unsigned int plug_id,
				  struct snd_bebob_stream_formation *formations)
{
	enum avc_bridgeco_plug_type plug_type;
	u8 *buf;
	unsigned int len, eid;
	int err;

	avc_bridgeco_fill_unit_addr(addr, plug_dir, AVC_BRIDGECO_PLUG_UNIT_ISOC, plug_id);

	err = avc_bridgeco_get_plug_type(bebob->unit, addr, &plug_type);
	if (err < 0) {
		dev_err(&bebob->unit->device,
			"Fail to get type for isoc %d plug 0: %d\n", plug_dir, err);
		return err;
	} else if (plug_type != AVC_BRIDGECO_PLUG_TYPE_ISOC)
		return -ENXIO;

	buf = kmalloc(FORMAT_MAXIMUM_LENGTH, GFP_KERNEL);
	if (buf == NULL)
		return -ENOMEM;

	for (eid = 0; eid < SND_BEBOB_STRM_FMT_ENTRIES; ++eid) {
		avc_bridgeco_fill_unit_addr(addr, plug_dir, AVC_BRIDGECO_PLUG_UNIT_ISOC, plug_id);

		len = FORMAT_MAXIMUM_LENGTH;
		err = avc_bridgeco_get_plug_strm_fmt(bebob->unit, addr, buf, &len, eid);
		// No entries remained.
		if (err == -EINVAL && eid > 0) {
			err = 0;
			break;
		} else if (err < 0) {
			dev_err(&bebob->unit->device,
				"fail to get stream format %d for isoc %d plug %d:%d\n",
				eid, plug_dir, plug_id, err);
			break;
		}

		err = parse_stream_formation(buf, len, formations);
		if (err < 0)
			break;
	}

	kfree(buf);
	return err;
}

static int detect_midi_ports(struct snd_bebob *bebob,
			     const struct snd_bebob_stream_formation *formats,
			     u8 addr[AVC_BRIDGECO_ADDR_BYTES], enum avc_bridgeco_plug_dir plug_dir,
			     unsigned int plug_count, unsigned int *midi_ports)
{
	int i;
	int err = 0;

	*midi_ports = 0;

	/// Detect the number of available MIDI ports when packet has MIDI conformant data channel.
	for (i = 0; i < SND_BEBOB_STRM_FMT_ENTRIES; ++i) {
		if (formats[i].midi > 0)
			break;
	}
	if (i >= SND_BEBOB_STRM_FMT_ENTRIES)
		return 0;

	for (i = 0; i < plug_count; ++i) {
		enum avc_bridgeco_plug_type plug_type;
		unsigned int ch_count;

		avc_bridgeco_fill_unit_addr(addr, plug_dir, AVC_BRIDGECO_PLUG_UNIT_EXT, i);

		err = avc_bridgeco_get_plug_type(bebob->unit, addr, &plug_type);
		if (err < 0) {
			dev_err(&bebob->unit->device,
				"fail to get type for external %d plug %d: %d\n",
				plug_dir, i, err);
			break;
		} else if (plug_type != AVC_BRIDGECO_PLUG_TYPE_MIDI) {
			continue;
		}

		err = avc_bridgeco_get_plug_ch_count(bebob->unit, addr, &ch_count);
		if (err < 0)
			break;
		// Yamaha GO44, GO46, Terratec Phase 24, Phase x24 reports 0 for the number of
		// channels in external output plug 3 (MIDI type) even if it has a pair of physical
		// MIDI jacks. As a workaround, assume it as one.
		if (ch_count == 0)
			ch_count = 1;
		*midi_ports += ch_count;
	}

	return err;
}

static int
seek_msu_sync_input_plug(struct snd_bebob *bebob)
{
	u8 plugs[AVC_PLUG_INFO_BUF_BYTES], addr[AVC_BRIDGECO_ADDR_BYTES];
	unsigned int i;
	enum avc_bridgeco_plug_type type;
	int err;

	/* Get the number of Music Sub Unit for both direction. */
	err = avc_general_get_plug_info(bebob->unit, 0x0c, 0x00, 0x00, plugs);
	if (err < 0) {
		dev_err(&bebob->unit->device,
			"fail to get info for MSU in/out plugs: %d\n",
			err);
		goto end;
	}

	/* seek destination plugs for 'MSU sync input' */
	bebob->sync_input_plug = -1;
	for (i = 0; i < plugs[0]; i++) {
		avc_bridgeco_fill_msu_addr(addr, AVC_BRIDGECO_PLUG_DIR_IN, i);
		err = avc_bridgeco_get_plug_type(bebob->unit, addr, &type);
		if (err < 0) {
			dev_err(&bebob->unit->device,
				"fail to get type for MSU in plug %d: %d\n",
				i, err);
			goto end;
		}

		if (type == AVC_BRIDGECO_PLUG_TYPE_SYNC) {
			bebob->sync_input_plug = i;
			break;
		}
	}
end:
	return err;
}

int snd_bebob_stream_discover(struct snd_bebob *bebob)
{
	const struct snd_bebob_clock_spec *clk_spec = bebob->spec->clock;
	u8 plugs[AVC_PLUG_INFO_BUF_BYTES], addr[AVC_BRIDGECO_ADDR_BYTES];
	int err;

	/* the number of plugs for isoc in/out, ext in/out  */
	err = avc_general_get_plug_info(bebob->unit, 0x1f, 0x07, 0x00, plugs);
	if (err < 0) {
		dev_err(&bebob->unit->device,
		"fail to get info for isoc/external in/out plugs: %d\n",
			err);
		goto end;
	}

	/*
	 * This module supports at least one isoc input plug and one isoc
	 * output plug.
	 */
	if ((plugs[0] == 0) || (plugs[1] == 0)) {
		err = -ENOSYS;
		goto end;
	}

	err = fill_stream_formations(bebob, addr, AVC_BRIDGECO_PLUG_DIR_IN, 0,
				     bebob->rx_stream_formations);
	if (err < 0)
		goto end;

	err = fill_stream_formations(bebob, addr, AVC_BRIDGECO_PLUG_DIR_OUT, 0,
				     bebob->tx_stream_formations);
	if (err < 0)
		goto end;

	err = detect_midi_ports(bebob, bebob->tx_stream_formations, addr, AVC_BRIDGECO_PLUG_DIR_IN,
				plugs[2], &bebob->midi_input_ports);
	if (err < 0)
		goto end;

	err = detect_midi_ports(bebob, bebob->rx_stream_formations, addr, AVC_BRIDGECO_PLUG_DIR_OUT,
				plugs[3], &bebob->midi_output_ports);
	if (err < 0)
		goto end;

	/* for check source of clock later */
	if (!clk_spec)
		err = seek_msu_sync_input_plug(bebob);
end:
	return err;
}

void snd_bebob_stream_lock_changed(struct snd_bebob *bebob)
{
	bebob->dev_lock_changed = true;
	wake_up(&bebob->hwdep_wait);
}

int snd_bebob_stream_lock_try(struct snd_bebob *bebob)
{
	int err;

	spin_lock_irq(&bebob->lock);

	/* user land lock this */
	if (bebob->dev_lock_count < 0) {
		err = -EBUSY;
		goto end;
	}

	/* this is the first time */
	if (bebob->dev_lock_count++ == 0)
		snd_bebob_stream_lock_changed(bebob);
	err = 0;
end:
	spin_unlock_irq(&bebob->lock);
	return err;
}

void snd_bebob_stream_lock_release(struct snd_bebob *bebob)
{
	spin_lock_irq(&bebob->lock);

	if (WARN_ON(bebob->dev_lock_count <= 0))
		goto end;
	if (--bebob->dev_lock_count == 0)
		snd_bebob_stream_lock_changed(bebob);
end:
	spin_unlock_irq(&bebob->lock);
}