aboutsummaryrefslogtreecommitdiffstats
path: root/sound/usb/stream.c
blob: 541ab19101ebdb899ca682456dae9f928c3164f0 (plain) (blame)
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
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 */


#include <linux/init.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/usb/audio.h>
#include <linux/usb/audio-v2.h>
#include <linux/usb/audio-v3.h>

#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/control.h>
#include <sound/tlv.h>

#include "usbaudio.h"
#include "card.h"
#include "proc.h"
#include "quirks.h"
#include "endpoint.h"
#include "pcm.h"
#include "helper.h"
#include "format.h"
#include "clock.h"
#include "stream.h"
#include "power.h"
#include "media.h"

static void audioformat_free(struct audioformat *fp)
{
	list_del(&fp->list); /* unlink for avoiding double-free */
	kfree(fp->rate_table);
	kfree(fp->chmap);
	kfree(fp);
}

/*
 * free a substream
 */
static void free_substream(struct snd_usb_substream *subs)
{
	struct audioformat *fp, *n;

	if (!subs->num_formats)
		return; /* not initialized */
	list_for_each_entry_safe(fp, n, &subs->fmt_list, list)
		audioformat_free(fp);
	kfree(subs->str_pd);
	snd_media_stream_delete(subs);
}


/*
 * free a usb stream instance
 */
static void snd_usb_audio_stream_free(struct snd_usb_stream *stream)
{
	free_substream(&stream->substream[0]);
	free_substream(&stream->substream[1]);
	list_del(&stream->list);
	kfree(stream);
}

static void snd_usb_audio_pcm_free(struct snd_pcm *pcm)
{
	struct snd_usb_stream *stream = pcm->private_data;
	if (stream) {
		stream->pcm = NULL;
		snd_usb_audio_stream_free(stream);
	}
}

/*
 * initialize the substream instance.
 */

static void snd_usb_init_substream(struct snd_usb_stream *as,
				   int stream,
				   struct audioformat *fp,
				   struct snd_usb_power_domain *pd)
{
	struct snd_usb_substream *subs = &as->substream[stream];

	INIT_LIST_HEAD(&subs->fmt_list);
	spin_lock_init(&subs->lock);

	subs->stream = as;
	subs->direction = stream;
	subs->dev = as->chip->dev;
	subs->txfr_quirk = !!(as->chip->quirk_flags & QUIRK_FLAG_ALIGN_TRANSFER);
	subs->tx_length_quirk = as->chip->tx_length_quirk;
	subs->speed = snd_usb_get_speed(subs->dev);
	subs->pkt_offset_adj = 0;
	subs->stream_offset_adj = 0;

	snd_usb_set_pcm_ops(as->pcm, stream);

	list_add_tail(&fp->list, &subs->fmt_list);
	subs->formats |= fp->formats;
	subs->num_formats++;
	subs->fmt_type = fp->fmt_type;
	subs->ep_num = fp->endpoint;
	if (fp->channels > subs->channels_max)
		subs->channels_max = fp->channels;

	if (pd) {
		subs->str_pd = pd;
		/* Initialize Power Domain to idle status D1 */
		snd_usb_power_domain_set(subs->stream->chip, pd,
					 UAC3_PD_STATE_D1);
	}

	snd_usb_preallocate_buffer(subs);
}

/* kctl callbacks for usb-audio channel maps */
static int usb_chmap_ctl_info(struct snd_kcontrol *kcontrol,
			      struct snd_ctl_elem_info *uinfo)
{
	struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
	struct snd_usb_substream *subs = info->private_data;

	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
	uinfo->count = subs->channels_max;
	uinfo->value.integer.min = 0;
	uinfo->value.integer.max = SNDRV_CHMAP_LAST;
	return 0;
}

/* check whether a duplicated entry exists in the audiofmt list */
static bool have_dup_chmap(struct snd_usb_substream *subs,
			   struct audioformat *fp)
{
	struct audioformat *prev = fp;

	list_for_each_entry_continue_reverse(prev, &subs->fmt_list, list) {
		if (prev->chmap &&
		    !memcmp(prev->chmap, fp->chmap, sizeof(*fp->chmap)))
			return true;
	}
	return false;
}

static int usb_chmap_ctl_tlv(struct snd_kcontrol *kcontrol, int op_flag,
			     unsigned int size, unsigned int __user *tlv)
{
	struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
	struct snd_usb_substream *subs = info->private_data;
	struct audioformat *fp;
	unsigned int __user *dst;
	int count = 0;

	if (size < 8)
		return -ENOMEM;
	if (put_user(SNDRV_CTL_TLVT_CONTAINER, tlv))
		return -EFAULT;
	size -= 8;
	dst = tlv + 2;
	list_for_each_entry(fp, &subs->fmt_list, list) {
		int i, ch_bytes;

		if (!fp->chmap)
			continue;
		if (have_dup_chmap(subs, fp))
			continue;
		/* copy the entry */
		ch_bytes = fp->chmap->channels * 4;
		if (size < 8 + ch_bytes)
			return -ENOMEM;
		if (put_user(SNDRV_CTL_TLVT_CHMAP_FIXED, dst) ||
		    put_user(ch_bytes, dst + 1))
			return -EFAULT;
		dst += 2;
		for (i = 0; i < fp->chmap->channels; i++, dst++) {
			if (put_user(fp->chmap->map[i], dst))
				return -EFAULT;
		}

		count += 8 + ch_bytes;
		size -= 8 + ch_bytes;
	}
	if (put_user(count, tlv + 1))
		return -EFAULT;
	return 0;
}

static int usb_chmap_ctl_get(struct snd_kcontrol *kcontrol,
			     struct snd_ctl_elem_value *ucontrol)
{
	struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
	struct snd_usb_substream *subs = info->private_data;
	struct snd_pcm_chmap_elem *chmap = NULL;
	int i = 0;

	if (subs->cur_audiofmt)
		chmap = subs->cur_audiofmt->chmap;
	if (chmap) {
		for (i = 0; i < chmap->channels; i++)
			ucontrol->value.integer.value[i] = chmap->map[i];
	}
	for (; i < subs->channels_max; i++)
		ucontrol->value.integer.value[i] = 0;
	return 0;
}

/* create a chmap kctl assigned to the given USB substream */
static int add_chmap(struct snd_pcm *pcm, int stream,
		     struct snd_usb_substream *subs)
{
	struct audioformat *fp;
	struct snd_pcm_chmap *chmap;
	struct snd_kcontrol *kctl;
	int err;

	list_for_each_entry(fp, &subs->fmt_list, list)
		if (fp->chmap)
			goto ok;
	/* no chmap is found */
	return 0;

 ok:
	err = snd_pcm_add_chmap_ctls(pcm, stream, NULL, 0, 0, &chmap);
	if (err < 0)
		return err;

	/* override handlers */
	chmap->private_data = subs;
	kctl = chmap->kctl;
	kctl->info = usb_chmap_ctl_info;
	kctl->get = usb_chmap_ctl_get;
	kctl->tlv.c = usb_chmap_ctl_tlv;

	return 0;
}

/* convert from USB ChannelConfig bits to ALSA chmap element */
static struct snd_pcm_chmap_elem *convert_chmap(int channels, unsigned int bits,
						int protocol)
{
	static const unsigned int uac1_maps[] = {
		SNDRV_CHMAP_FL,		/* left front */
		SNDRV_CHMAP_FR,		/* right front */
		SNDRV_CHMAP_FC,		/* center front */
		SNDRV_CHMAP_LFE,	/* LFE */
		SNDRV_CHMAP_SL,		/* left surround */
		SNDRV_CHMAP_SR,		/* right surround */
		SNDRV_CHMAP_FLC,	/* left of center */
		SNDRV_CHMAP_FRC,	/* right of center */
		SNDRV_CHMAP_RC,		/* surround */
		SNDRV_CHMAP_SL,		/* side left */
		SNDRV_CHMAP_SR,		/* side right */
		SNDRV_CHMAP_TC,		/* top */
		0 /* terminator */
	};
	static const unsigned int uac2_maps[] = {
		SNDRV_CHMAP_FL,		/* front left */
		SNDRV_CHMAP_FR,		/* front right */
		SNDRV_CHMAP_FC,		/* front center */
		SNDRV_CHMAP_LFE,	/* LFE */
		SNDRV_CHMAP_RL,		/* back left */
		SNDRV_CHMAP_RR,		/* back right */
		SNDRV_CHMAP_FLC,	/* front left of center */
		SNDRV_CHMAP_FRC,	/* front right of center */
		SNDRV_CHMAP_RC,		/* back center */
		SNDRV_CHMAP_SL,		/* side left */
		SNDRV_CHMAP_SR,		/* side right */
		SNDRV_CHMAP_TC,		/* top center */
		SNDRV_CHMAP_TFL,	/* top front left */
		SNDRV_CHMAP_TFC,	/* top front center */
		SNDRV_CHMAP_TFR,	/* top front right */
		SNDRV_CHMAP_TRL,	/* top back left */
		SNDRV_CHMAP_TRC,	/* top back center */
		SNDRV_CHMAP_TRR,	/* top back right */
		SNDRV_CHMAP_TFLC,	/* top front left of center */
		SNDRV_CHMAP_TFRC,	/* top front right of center */
		SNDRV_CHMAP_LLFE,	/* left LFE */
		SNDRV_CHMAP_RLFE,	/* right LFE */
		SNDRV_CHMAP_TSL,	/* top side left */
		SNDRV_CHMAP_TSR,	/* top side right */
		SNDRV_CHMAP_BC,		/* bottom center */
		SNDRV_CHMAP_RLC,	/* back left of center */
		SNDRV_CHMAP_RRC,	/* back right of center */
		0 /* terminator */
	};
	struct snd_pcm_chmap_elem *chmap;
	const unsigned int *maps;
	int c;

	if (channels > ARRAY_SIZE(chmap->map))
		return NULL;

	chmap = kzalloc(sizeof(*chmap), GFP_KERNEL);
	if (!chmap)
		return NULL;

	maps = protocol == UAC_VERSION_2 ? uac2_maps : uac1_maps;
	chmap->channels = channels;
	c = 0;

	if (bits) {
		for (; bits && *maps; maps++, bits >>= 1)
			if (bits & 1)
				chmap->map[c++] = *maps;
	} else {
		/* If we're missing wChannelConfig, then guess something
		    to make sure the channel map is not skipped entirely */
		if (channels == 1)
			chmap->map[c++] = SNDRV_CHMAP_MONO;
		else
			for (; c < channels && *maps; maps++)
				chmap->map[c++] = *maps;
	}

	for (; c < channels; c++)
		chmap->map[c] = SNDRV_CHMAP_UNKNOWN;

	return chmap;
}

/* UAC3 device stores channels information in Cluster Descriptors */
static struct
snd_pcm_chmap_elem *convert_chmap_v3(struct uac3_cluster_header_descriptor
								*cluster)
{
	unsigned int channels = cluster->bNrChannels;
	struct snd_pcm_chmap_elem *chmap;
	void *p = cluster;
	int len, c;

	if (channels > ARRAY_SIZE(chmap->map))
		return NULL;

	chmap = kzalloc(sizeof(*chmap), GFP_KERNEL);
	if (!chmap)
		return NULL;

	len = le16_to_cpu(cluster->wLength);
	c = 0;
	p += sizeof(struct uac3_cluster_header_descriptor);

	while (((p - (void *)cluster) < len) && (c < channels)) {
		struct uac3_cluster_segment_descriptor *cs_desc = p;
		u16 cs_len;
		u8 cs_type;

		cs_len = le16_to_cpu(cs_desc->wLength);
		cs_type = cs_desc->bSegmentType;

		if (cs_type == UAC3_CHANNEL_INFORMATION) {
			struct uac3_cluster_information_segment_descriptor *is = p;
			unsigned char map;

			/*
			 * TODO: this conversion is not complete, update it
			 * after adding UAC3 values to asound.h
			 */
			switch (is->bChRelationship) {
			case UAC3_CH_MONO:
				map = SNDRV_CHMAP_MONO;
				break;
			case UAC3_CH_LEFT:
			case UAC3_CH_FRONT_LEFT:
			case UAC3_CH_HEADPHONE_LEFT:
				map = SNDRV_CHMAP_FL;
				break;
			case UAC3_CH_RIGHT:
			case UAC3_CH_FRONT_RIGHT:
			case UAC3_CH_HEADPHONE_RIGHT:
				map = SNDRV_CHMAP_FR;
				break;
			case UAC3_CH_FRONT_CENTER:
				map = SNDRV_CHMAP_FC;
				break;
			case UAC3_CH_FRONT_LEFT_OF_CENTER:
				map = SNDRV_CHMAP_FLC;
				break;
			case UAC3_CH_FRONT_RIGHT_OF_CENTER:
				map = SNDRV_CHMAP_FRC;
				break;
			case UAC3_CH_SIDE_LEFT:
				map = SNDRV_CHMAP_SL;
				break;
			case UAC3_CH_SIDE_RIGHT:
				map = SNDRV_CHMAP_SR;
				break;
			case UAC3_CH_BACK_LEFT:
				map = SNDRV_CHMAP_RL;
				break;
			case UAC3_CH_BACK_RIGHT:
				map = SNDRV_CHMAP_RR;
				break;
			case UAC3_CH_BACK_CENTER:
				map = SNDRV_CHMAP_RC;
				break;
			case UAC3_CH_BACK_LEFT_OF_CENTER:
				map = SNDRV_CHMAP_RLC;
				break;
			case UAC3_CH_BACK_RIGHT_OF_CENTER:
				map = SNDRV_CHMAP_RRC;
				break;
			case UAC3_CH_TOP_CENTER:
				map = SNDRV_CHMAP_TC;
				break;
			case UAC3_CH_TOP_FRONT_LEFT:
				map = SNDRV_CHMAP_TFL;
				break;
			case UAC3_CH_TOP_FRONT_RIGHT:
				map = SNDRV_CHMAP_TFR;
				break;
			case UAC3_CH_TOP_FRONT_CENTER:
				map = SNDRV_CHMAP_TFC;
				break;
			case UAC3_CH_TOP_FRONT_LOC:
				map = SNDRV_CHMAP_TFLC;
				break;
			case UAC3_CH_TOP_FRONT_ROC:
				map = SNDRV_CHMAP_TFRC;
				break;
			case UAC3_CH_TOP_SIDE_LEFT:
				map = SNDRV_CHMAP_TSL;
				break;
			case UAC3_CH_TOP_SIDE_RIGHT:
				map = SNDRV_CHMAP_TSR;
				break;
			case UAC3_CH_TOP_BACK_LEFT:
				map = SNDRV_CHMAP_TRL;
				break;
			case UAC3_CH_TOP_BACK_RIGHT:
				map = SNDRV_CHMAP_TRR;
				break;
			case UAC3_CH_TOP_BACK_CENTER:
				map = SNDRV_CHMAP_TRC;
				break;
			case UAC3_CH_BOTTOM_CENTER:
				map = SNDRV_CHMAP_BC;
				break;
			case UAC3_CH_LOW_FREQUENCY_EFFECTS:
				map = SNDRV_CHMAP_LFE;
				break;
			case UAC3_CH_LFE_LEFT:
				map = SNDRV_CHMAP_LLFE;
				break;
			case UAC3_CH_LFE_RIGHT:
				map = SNDRV_CHMAP_RLFE;
				break;
			case UAC3_CH_RELATIONSHIP_UNDEFINED:
			default:
				map = SNDRV_CHMAP_UNKNOWN;
				break;
			}
			chmap->map[c++] = map;
		}
		p += cs_len;
	}

	if (channels < c)
		pr_err("%s: channel number mismatch\n", __func__);

	chmap->channels = channels;

	for (; c < channels; c++)
		chmap->map[c] = SNDRV_CHMAP_UNKNOWN;

	return chmap;
}

/*
 * add this endpoint to the chip instance.
 * if a stream with the same endpoint already exists, append to it.
 * if not, create a new pcm stream. note, fp is added to the substream
 * fmt_list and will be freed on the chip instance release. do not free
 * fp or do remove it from the substream fmt_list to avoid double-free.
 */
static int __snd_usb_add_audio_stream(struct snd_usb_audio *chip,
				      int stream,
				      struct audioformat *fp,
				      struct snd_usb_power_domain *pd)

{
	struct snd_usb_stream *as;
	struct snd_usb_substream *subs;
	struct snd_pcm *pcm;
	int err;

	list_for_each_entry(as, &chip->pcm_list, list) {
		if (as->fmt_type != fp->fmt_type)
			continue;
		subs = &as->substream[stream];
		if (subs->ep_num == fp->endpoint) {
			list_add_tail(&fp->list, &subs->fmt_list);
			subs->num_formats++;
			subs->formats |= fp->formats;
			return 0;
		}
	}
	/* look for an empty stream */
	list_for_each_entry(as, &chip->pcm_list, list) {
		if (as->fmt_type != fp->fmt_type)
			continue;
		subs = &as->substream[stream];
		if (subs->ep_num)
			continue;
		if (snd_device_get_state(chip->card, as->pcm) !=
		    SNDRV_DEV_BUILD)
			chip->need_delayed_register = true;
		err = snd_pcm_new_stream(as->pcm, stream, 1);
		if (err < 0)
			return err;
		snd_usb_init_substream(as, stream, fp, pd);
		return add_chmap(as->pcm, stream, subs);
	}

	/* create a new pcm */
	as = kzalloc(sizeof(*as), GFP_KERNEL);
	if (!as)
		return -ENOMEM;
	as->pcm_index = chip->pcm_devs;
	as->chip = chip;
	as->fmt_type = fp->fmt_type;
	err = snd_pcm_new(chip->card, "USB Audio", chip->pcm_devs,
			  stream == SNDRV_PCM_STREAM_PLAYBACK ? 1 : 0,
			  stream == SNDRV_PCM_STREAM_PLAYBACK ? 0 : 1,
			  &pcm);
	if (err < 0) {
		kfree(as);
		return err;
	}
	as->pcm = pcm;
	pcm->private_data = as;
	pcm->private_free = snd_usb_audio_pcm_free;
	pcm->info_flags = 0;
	if (chip->pcm_devs > 0)
		sprintf(pcm->name, "USB Audio #%d", chip->pcm_devs);
	else
		strcpy(pcm->name, "USB Audio");

	snd_usb_init_substream(as, stream, fp, pd);

	/*
	 * Keep using head insertion for M-Audio Audiophile USB (tm) which has a
	 * fix to swap capture stream order in conf/cards/USB-audio.conf
	 */
	if (chip->usb_id == USB_ID(0x0763, 0x2003))
		list_add(&as->list, &chip->pcm_list);
	else
		list_add_tail(&as->list, &chip->pcm_list);

	chip->pcm_devs++;

	snd_usb_proc_pcm_format_add(as);

	return add_chmap(pcm, stream, &as->substream[stream]);
}

int snd_usb_add_audio_stream(struct snd_usb_audio *chip,
			     int stream,
			     struct audioformat *fp)
{
	return __snd_usb_add_audio_stream(chip, stream, fp, NULL);
}

static int snd_usb_add_audio_stream_v3(struct snd_usb_audio *chip,
				       int stream,
				       struct audioformat *fp,
				       struct snd_usb_power_domain *pd)
{
	return __snd_usb_add_audio_stream(chip, stream, fp, pd);
}

static int parse_uac_endpoint_attributes(struct snd_usb_audio *chip,
					 struct usb_host_interface *alts,
					 int protocol, int iface_no)
{
	/* parsed with a v1 header here. that's ok as we only look at the
	 * header first which is the same for both versions */
	struct uac_iso_endpoint_descriptor *csep;
	struct usb_interface_descriptor *altsd = get_iface_desc(alts);
	int attributes = 0;

	csep = snd_usb_find_desc(alts->endpoint[0].extra, alts->endpoint[0].extralen, NULL, USB_DT_CS_ENDPOINT);

	/* Creamware Noah has this descriptor after the 2nd endpoint */
	if (!csep && altsd->bNumEndpoints >= 2)
		csep = snd_usb_find_desc(alts->endpoint[1].extra, alts->endpoint[1].extralen, NULL, USB_DT_CS_ENDPOINT);

	/*
	 * If we can't locate the USB_DT_CS_ENDPOINT descriptor in the extra
	 * bytes after the first endpoint, go search the entire interface.
	 * Some devices have it directly *before* the standard endpoint.
	 */
	if (!csep)
		csep = snd_usb_find_desc(alts->extra, alts->extralen, NULL, USB_DT_CS_ENDPOINT);

	if (!csep || csep->bLength < 7 ||
	    csep->bDescriptorSubtype != UAC_EP_GENERAL)
		goto error;

	if (protocol == UAC_VERSION_1) {
		attributes = csep->bmAttributes;
	} else if (protocol == UAC_VERSION_2) {
		struct uac2_iso_endpoint_descriptor *csep2 =
			(struct uac2_iso_endpoint_descriptor *) csep;

		if (csep2->bLength < sizeof(*csep2))
			goto error;
		attributes = csep->bmAttributes & UAC_EP_CS_ATTR_FILL_MAX;

		/* emulate the endpoint attributes of a v1 device */
		if (csep2->bmControls & UAC2_CONTROL_PITCH)
			attributes |= UAC_EP_CS_ATTR_PITCH_CONTROL;
	} else { /* UAC_VERSION_3 */
		struct uac3_iso_endpoint_descriptor *csep3 =
			(struct uac3_iso_endpoint_descriptor *) csep;

		if (csep3->bLength < sizeof(*csep3))
			goto error;
		/* emulate the endpoint attributes of a v1 device */
		if (le32_to_cpu(csep3->bmControls) & UAC2_CONTROL_PITCH)
			attributes |= UAC_EP_CS_ATTR_PITCH_CONTROL;
	}

	return attributes;

 error:
	usb_audio_warn(chip,
		       "%u:%d : no or invalid class specific endpoint descriptor\n",
		       iface_no, altsd->bAlternateSetting);
	return 0;
}

/* find an input terminal descriptor (either UAC1 or UAC2) with the given
 * terminal id
 */
static void *
snd_usb_find_input_terminal_descriptor(struct usb_host_interface *ctrl_iface,
				       int terminal_id, int protocol)
{
	struct uac2_input_terminal_descriptor *term = NULL;

	while ((term = snd_usb_find_csint_desc(ctrl_iface->extra,
					       ctrl_iface->extralen,
					       term, UAC_INPUT_TERMINAL))) {
		if (!snd_usb_validate_audio_desc(term, protocol))
			continue;
		if (term->bTerminalID == terminal_id)
			return term;
	}

	return NULL;
}

static void *
snd_usb_find_output_terminal_descriptor(struct usb_host_interface *ctrl_iface,
					int terminal_id, int protocol)
{
	/* OK to use with both UAC2 and UAC3 */
	struct uac2_output_terminal_descriptor *term = NULL;

	while ((term = snd_usb_find_csint_desc(ctrl_iface->extra,
					       ctrl_iface->extralen,
					       term, UAC_OUTPUT_TERMINAL))) {
		if (!snd_usb_validate_audio_desc(term, protocol))
			continue;
		if (term->bTerminalID == terminal_id)
			return term;
	}

	return NULL;
}

static struct audioformat *
audio_format_alloc_init(struct snd_usb_audio *chip,
		       struct usb_host_interface *alts,
		       int protocol, int iface_no, int altset_idx,
		       int altno, int num_channels, int clock)
{
	struct audioformat *fp;

	fp = kzalloc(sizeof(*fp), GFP_KERNEL);
	if (!fp)
		return NULL;

	fp->iface = iface_no;
	fp->altsetting = altno;
	fp->altset_idx = altset_idx;
	fp->endpoint = get_endpoint(alts, 0)->bEndpointAddress;
	fp->ep_attr = get_endpoint(alts, 0)->bmAttributes;
	fp->datainterval = snd_usb_parse_datainterval(chip, alts);
	fp->protocol = protocol;
	fp->maxpacksize = le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize);
	fp->channels = num_channels;
	if (snd_usb_get_speed(chip->dev) == USB_SPEED_HIGH)
		fp->maxpacksize = (((fp->maxpacksize >> 11) & 3) + 1)
				* (fp->maxpacksize & 0x7ff);
	fp->clock = clock;
	INIT_LIST_HEAD(&fp->list);

	return fp;
}

static struct audioformat *
snd_usb_get_audioformat_uac12(struct snd_usb_audio *chip,
			      struct usb_host_interface *alts,
			      int protocol, int iface_no, int altset_idx,
			      int altno, int stream, int bm_quirk)
{
	struct usb_device *dev = chip->dev;
	struct uac_format_type_i_continuous_descriptor *fmt;
	unsigned int num_channels = 0, chconfig = 0;
	struct audioformat *fp;
	int clock = 0;
	u64 format;

	/* get audio formats */
	if (protocol == UAC_VERSION_1) {
		struct uac1_as_header_descriptor *as =
			snd_usb_find_csint_desc(alts->extra, alts->extralen,
						NULL, UAC_AS_GENERAL);
		struct uac_input_terminal_descriptor *iterm;

		if (!as) {
			dev_err(&dev->dev,
				"%u:%d : UAC_AS_GENERAL descriptor not found\n",
				iface_no, altno);
			return NULL;
		}

		if (as->bLength < sizeof(*as)) {
			dev_err(&dev->dev,
				"%u:%d : invalid UAC_AS_GENERAL desc\n",
				iface_no, altno);
			return NULL;
		}

		format = le16_to_cpu(as->wFormatTag); /* remember the format value */

		iterm = snd_usb_find_input_terminal_descriptor(chip->ctrl_intf,
							       as->bTerminalLink,
							       protocol);
		if (iterm) {
			num_channels = iterm->bNrChannels;
			chconfig = le16_to_cpu(iterm->wChannelConfig);
		}
	} else { /* UAC_VERSION_2 */
		struct uac2_input_terminal_descriptor *input_term;
		struct uac2_output_terminal_descriptor *output_term;
		struct uac2_as_header_descriptor *as =
			snd_usb_find_csint_desc(alts->extra, alts->extralen,
						NULL, UAC_AS_GENERAL);

		if (!as) {
			dev_err(&dev->dev,
				"%u:%d : UAC_AS_GENERAL descriptor not found\n",
				iface_no, altno);
			return NULL;
		}

		if (as->bLength < sizeof(*as)) {
			dev_err(&dev->dev,
				"%u:%d : invalid UAC_AS_GENERAL desc\n",
				iface_no, altno);
			return NULL;
		}

		num_channels = as->bNrChannels;
		format = le32_to_cpu(as->bmFormats);
		chconfig = le32_to_cpu(as->bmChannelConfig);

		/*
		 * lookup the terminal associated to this interface
		 * to extract the clock
		 */
		input_term = snd_usb_find_input_terminal_descriptor(chip->ctrl_intf,
								    as->bTerminalLink,
								    protocol);
		if (input_term) {
			clock = input_term->bCSourceID;
			if (!chconfig && (num_channels == input_term->bNrChannels))
				chconfig = le32_to_cpu(input_term->bmChannelConfig);
			goto found_clock;
		}

		output_term = snd_usb_find_output_terminal_descriptor(chip->ctrl_intf,
								      as->bTerminalLink,
								      protocol);
		if (output_term) {
			clock = output_term->bCSourceID;
			goto found_clock;
		}

		dev_err(&dev->dev,
			"%u:%d : bogus bTerminalLink %d\n",
			iface_no, altno, as->bTerminalLink);
		return NULL;
	}

found_clock:
	/* get format type */
	fmt = snd_usb_find_csint_desc(alts->extra, alts->extralen,
				      NULL, UAC_FORMAT_TYPE);
	if (!fmt) {
		dev_err(&dev->dev,
			"%u:%d : no UAC_FORMAT_TYPE desc\n",
			iface_no, altno);
		return NULL;
	}
	if (((protocol == UAC_VERSION_1) && (fmt->bLength < 8))
			|| ((protocol == UAC_VERSION_2) &&
					(fmt->bLength < 6))) {
		dev_err(&dev->dev,
			"%u:%d : invalid UAC_FORMAT_TYPE desc\n",
			iface_no, altno);
		return NULL;
	}

	/*
	 * Blue Microphones workaround: The last altsetting is
	 * identical with the previous one, except for a larger
	 * packet size, but is actually a mislabeled two-channel
	 * setting; ignore it.
	 *
	 * Part 2: analyze quirk flag and format
	 */
	if (bm_quirk && fmt->bNrChannels == 1 && fmt->bSubframeSize == 2)
		return NULL;

	fp = audio_format_alloc_init(chip, alts, protocol, iface_no,
				     altset_idx, altno, num_channels, clock);
	if (!fp)
		return ERR_PTR(-ENOMEM);

	fp->attributes = parse_uac_endpoint_attributes(chip, alts, protocol,
						       iface_no);

	/* some quirks for attributes here */
	snd_usb_audioformat_attributes_quirk(chip, fp, stream);

	/* ok, let's parse further... */
	if (snd_usb_parse_audio_format(chip, fp, format,
					fmt, stream) < 0) {
		audioformat_free(fp);
		return NULL;
	}

	/* Create chmap */
	if (fp->channels != num_channels)
		chconfig = 0;

	fp->chmap = convert_chmap(fp->channels, chconfig, protocol);

	return fp;
}

static struct audioformat *
snd_usb_get_audioformat_uac3(struct snd_usb_audio *chip,
			     struct usb_host_interface *alts,
			     struct snd_usb_power_domain **pd_out,
			     int iface_no, int altset_idx,
			     int altno, int stream)
{
	struct usb_device *dev = chip->dev;
	struct uac3_input_terminal_descriptor *input_term;
	struct uac3_output_terminal_descriptor *output_term;
	struct uac3_cluster_header_descriptor *cluster;
	struct uac3_as_header_descriptor *as = NULL;
	struct uac3_hc_descriptor_header hc_header;
	struct snd_pcm_chmap_elem *chmap;
	struct snd_usb_power_domain *pd;
	unsigned char badd_profile;
	u64 badd_formats = 0;
	unsigned int num_channels;
	struct audioformat *fp;
	u16 cluster_id, wLength;
	int clock = 0;
	int err;

	badd_profile = chip->badd_profile;

	if (badd_profile >= UAC3_FUNCTION_SUBCLASS_GENERIC_IO) {
		unsigned int maxpacksize =
			le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize);

		switch (maxpacksize) {
		default:
			dev_err(&dev->dev,
				"%u:%d : incorrect wMaxPacketSize for BADD profile\n",
				iface_no, altno);
			return NULL;
		case UAC3_BADD_EP_MAXPSIZE_SYNC_MONO_16:
		case UAC3_BADD_EP_MAXPSIZE_ASYNC_MONO_16:
			badd_formats = SNDRV_PCM_FMTBIT_S16_LE;
			num_channels = 1;
			break;
		case UAC3_BADD_EP_MAXPSIZE_SYNC_MONO_24:
		case UAC3_BADD_EP_MAXPSIZE_ASYNC_MONO_24:
			badd_formats = SNDRV_PCM_FMTBIT_S24_3LE;
			num_channels = 1;
			break;
		case UAC3_BADD_EP_MAXPSIZE_SYNC_STEREO_16:
		case UAC3_BADD_EP_MAXPSIZE_ASYNC_STEREO_16:
			badd_formats = SNDRV_PCM_FMTBIT_S16_LE;
			num_channels = 2;
			break;
		case UAC3_BADD_EP_MAXPSIZE_SYNC_STEREO_24:
		case UAC3_BADD_EP_MAXPSIZE_ASYNC_STEREO_24:
			badd_formats = SNDRV_PCM_FMTBIT_S24_3LE;
			num_channels = 2;
			break;
		}

		chmap = kzalloc(sizeof(*chmap), GFP_KERNEL);
		if (!chmap)
			return ERR_PTR(-ENOMEM);

		if (num_channels == 1) {
			chmap->map[0] = SNDRV_CHMAP_MONO;
		} else {
			chmap->map[0] = SNDRV_CHMAP_FL;
			chmap->map[1] = SNDRV_CHMAP_FR;
		}

		chmap->channels = num_channels;
		clock = UAC3_BADD_CS_ID9;
		goto found_clock;
	}

	as = snd_usb_find_csint_desc(alts->extra, alts->extralen,
				     NULL, UAC_AS_GENERAL);
	if (!as) {
		dev_err(&dev->dev,
			"%u:%d : UAC_AS_GENERAL descriptor not found\n",
			iface_no, altno);
		return NULL;
	}

	if (as->bLength < sizeof(*as)) {
		dev_err(&dev->dev,
			"%u:%d : invalid UAC_AS_GENERAL desc\n",
			iface_no, altno);
		return NULL;
	}

	cluster_id = le16_to_cpu(as->wClusterDescrID);
	if (!cluster_id) {
		dev_err(&dev->dev,
			"%u:%d : no cluster descriptor\n",
			iface_no, altno);
		return NULL;
	}

	/*
	 * Get number of channels and channel map through
	 * High Capability Cluster Descriptor
	 *
	 * First step: get High Capability header and
	 * read size of Cluster Descriptor
	 */
	err = snd_usb_ctl_msg(chip->dev,
			usb_rcvctrlpipe(chip->dev, 0),
			UAC3_CS_REQ_HIGH_CAPABILITY_DESCRIPTOR,
			USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
			cluster_id,
			snd_usb_ctrl_intf(chip),
			&hc_header, sizeof(hc_header));
	if (err < 0)
		return ERR_PTR(err);
	else if (err != sizeof(hc_header)) {
		dev_err(&dev->dev,
			"%u:%d : can't get High Capability descriptor\n",
			iface_no, altno);
		return ERR_PTR(-EIO);
	}

	/*
	 * Second step: allocate needed amount of memory
	 * and request Cluster Descriptor
	 */
	wLength = le16_to_cpu(hc_header.wLength);
	cluster = kzalloc(wLength, GFP_KERNEL);
	if (!cluster)
		return ERR_PTR(-ENOMEM);
	err = snd_usb_ctl_msg(chip->dev,
			usb_rcvctrlpipe(chip->dev, 0),
			UAC3_CS_REQ_HIGH_CAPABILITY_DESCRIPTOR,
			USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
			cluster_id,
			snd_usb_ctrl_intf(chip),
			cluster, wLength);
	if (err < 0) {
		kfree(cluster);
		return ERR_PTR(err);
	} else if (err != wLength) {
		dev_err(&dev->dev,
			"%u:%d : can't get Cluster Descriptor\n",
			iface_no, altno);
		kfree(cluster);
		return ERR_PTR(-EIO);
	}

	num_channels = cluster->bNrChannels;
	chmap = convert_chmap_v3(cluster);
	kfree(cluster);

	/*
	 * lookup the terminal associated to this interface
	 * to extract the clock
	 */
	input_term = snd_usb_find_input_terminal_descriptor(chip->ctrl_intf,
							    as->bTerminalLink,
							    UAC_VERSION_3);
	if (input_term) {
		clock = input_term->bCSourceID;
		goto found_clock;
	}

	output_term = snd_usb_find_output_terminal_descriptor(chip->ctrl_intf,
							      as->bTerminalLink,
							      UAC_VERSION_3);
	if (output_term) {
		clock = output_term->bCSourceID;
		goto found_clock;
	}

	dev_err(&dev->dev, "%u:%d : bogus bTerminalLink %d\n",
			iface_no, altno, as->bTerminalLink);
	kfree(chmap);
	return NULL;

found_clock:
	fp = audio_format_alloc_init(chip, alts, UAC_VERSION_3, iface_no,
				     altset_idx, altno, num_channels, clock);
	if (!fp) {
		kfree(chmap);
		return ERR_PTR(-ENOMEM);
	}

	fp->chmap = chmap;

	if (badd_profile >= UAC3_FUNCTION_SUBCLASS_GENERIC_IO) {
		fp->attributes = 0; /* No attributes */

		fp->fmt_type = UAC_FORMAT_TYPE_I;
		fp->formats = badd_formats;

		fp->nr_rates = 0;	/* SNDRV_PCM_RATE_CONTINUOUS */
		fp->rate_min = UAC3_BADD_SAMPLING_RATE;
		fp->rate_max = UAC3_BADD_SAMPLING_RATE;
		fp->rates = SNDRV_PCM_RATE_CONTINUOUS;

		pd = kzalloc(sizeof(*pd), GFP_KERNEL);
		if (!pd) {
			audioformat_free(fp);
			return NULL;
		}
		pd->pd_id = (stream == SNDRV_PCM_STREAM_PLAYBACK) ?
					UAC3_BADD_PD_ID10 : UAC3_BADD_PD_ID11;
		pd->pd_d1d0_rec = UAC3_BADD_PD_RECOVER_D1D0;
		pd->pd_d2d0_rec = UAC3_BADD_PD_RECOVER_D2D0;

	} else {
		fp->attributes = parse_uac_endpoint_attributes(chip, alts,
							       UAC_VERSION_3,
							       iface_no);

		pd = snd_usb_find_power_domain(chip->ctrl_intf,
					       as->bTerminalLink);

		/* ok, let's parse further... */
		if (snd_usb_parse_audio_format_v3(chip, fp, as, stream) < 0) {
			kfree(pd);
			audioformat_free(fp);
			return NULL;
		}
	}

	if (pd)
		*pd_out = pd;

	return fp;
}

static int __snd_usb_parse_audio_interface(struct snd_usb_audio *chip,
					   int iface_no,
					   bool *has_non_pcm, bool non_pcm)
{
	struct usb_device *dev;
	struct usb_interface *iface;
	struct usb_host_interface *alts;
	struct usb_interface_descriptor *altsd;
	int i, altno, err, stream;
	struct audioformat *fp = NULL;
	struct snd_usb_power_domain *pd = NULL;
	int num, protocol;

	dev = chip->dev;

	/* parse the interface's altsettings */
	iface = usb_ifnum_to_if(dev, iface_no);

	num = iface->num_altsetting;

	/*
	 * Dallas DS4201 workaround: It presents 5 altsettings, but the last
	 * one misses syncpipe, and does not produce any sound.
	 */
	if (chip->usb_id == USB_ID(0x04fa, 0x4201))
		num = 4;

	for (i = 0; i < num; i++) {
		alts = &iface->altsetting[i];
		altsd = get_iface_desc(alts);
		protocol = altsd->bInterfaceProtocol;
		/* skip invalid one */
		if (((altsd->bInterfaceClass != USB_CLASS_AUDIO ||
		      (altsd->bInterfaceSubClass != USB_SUBCLASS_AUDIOSTREAMING &&
		       altsd->bInterfaceSubClass != USB_SUBCLASS_VENDOR_SPEC)) &&
		     altsd->bInterfaceClass != USB_CLASS_VENDOR_SPEC) ||
		    altsd->bNumEndpoints < 1 ||
		    le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize) == 0)
			continue;
		/* must be isochronous */
		if ((get_endpoint(alts, 0)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) !=
		    USB_ENDPOINT_XFER_ISOC)
			continue;
		/* check direction */
		stream = (get_endpoint(alts, 0)->bEndpointAddress & USB_DIR_IN) ?
			SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
		altno = altsd->bAlternateSetting;

		if (snd_usb_apply_interface_quirk(chip, iface_no, altno))
			continue;

		/*
		 * Roland audio streaming interfaces are marked with protocols
		 * 0/1/2, but are UAC 1 compatible.
		 */
		if (USB_ID_VENDOR(chip->usb_id) == 0x0582 &&
		    altsd->bInterfaceClass == USB_CLASS_VENDOR_SPEC &&
		    protocol <= 2)
			protocol = UAC_VERSION_1;

		switch (protocol) {
		default:
			dev_dbg(&dev->dev, "%u:%d: unknown interface protocol %#02x, assuming v1\n",
				iface_no, altno, protocol);
			protocol = UAC_VERSION_1;
			fallthrough;
		case UAC_VERSION_1:
		case UAC_VERSION_2: {
			int bm_quirk = 0;

			/*
			 * Blue Microphones workaround: The last altsetting is
			 * identical with the previous one, except for a larger
			 * packet size, but is actually a mislabeled two-channel
			 * setting; ignore it.
			 *
			 * Part 1: prepare quirk flag
			 */
			if (altno == 2 && num == 3 &&
			    fp && fp->altsetting == 1 && fp->channels == 1 &&
			    fp->formats == SNDRV_PCM_FMTBIT_S16_LE &&
			    protocol == UAC_VERSION_1 &&
			    le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize) ==
							fp->maxpacksize * 2)
				bm_quirk = 1;

			fp = snd_usb_get_audioformat_uac12(chip, alts, protocol,
							   iface_no, i, altno,
							   stream, bm_quirk);
			break;
		}
		case UAC_VERSION_3:
			fp = snd_usb_get_audioformat_uac3(chip, alts, &pd,
						iface_no, i, altno, stream);
			break;
		}

		if (!fp)
			continue;
		else if (IS_ERR(fp))
			return PTR_ERR(fp);

		if (fp->fmt_type != UAC_FORMAT_TYPE_I)
			*has_non_pcm = true;
		if ((fp->fmt_type == UAC_FORMAT_TYPE_I) == non_pcm) {
			audioformat_free(fp);
			kfree(pd);
			fp = NULL;
			pd = NULL;
			continue;
		}

		snd_usb_audioformat_set_sync_ep(chip, fp);

		dev_dbg(&dev->dev, "%u:%d: add audio endpoint %#x\n", iface_no, altno, fp->endpoint);
		if (protocol == UAC_VERSION_3)
			err = snd_usb_add_audio_stream_v3(chip, stream, fp, pd);
		else
			err = snd_usb_add_audio_stream(chip, stream, fp);

		if (err < 0) {
			audioformat_free(fp);
			kfree(pd);
			return err;
		}

		/* add endpoints */
		err = snd_usb_add_endpoint(chip, fp->endpoint,
					   SND_USB_ENDPOINT_TYPE_DATA);
		if (err < 0)
			return err;

		if (fp->sync_ep) {
			err = snd_usb_add_endpoint(chip, fp->sync_ep,
						   fp->implicit_fb ?
						   SND_USB_ENDPOINT_TYPE_DATA :
						   SND_USB_ENDPOINT_TYPE_SYNC);
			if (err < 0)
				return err;
		}

		/* try to set the interface... */
		usb_set_interface(chip->dev, iface_no, 0);
		snd_usb_init_pitch(chip, fp);
		snd_usb_init_sample_rate(chip, fp, fp->rate_max);
		usb_set_interface(chip->dev, iface_no, altno);
	}
	return 0;
}

int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
{
	int err;
	bool has_non_pcm = false;

	/* parse PCM formats */
	err = __snd_usb_parse_audio_interface(chip, iface_no, &has_non_pcm, false);
	if (err < 0)
		return err;

	if (has_non_pcm) {
		/* parse non-PCM formats */
		err = __snd_usb_parse_audio_interface(chip, iface_no, &has_non_pcm, true);
		if (err < 0)
			return err;
	}

	return 0;
}