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ALSA: snd-usb: handle raw data format of UAC2 devices

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UAC2 compliant audio devices may announce the capability to transport
raw audio data on their endpoints. Catch this and handle it as
'special' stream on the ALSA side.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Reported-by: Andreas Koch <andreas@akdesigninc.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Daniel Mack 2013-03-17 20:07:25 +08:00 committed by Takashi Iwai
parent 2fcdb06d49
commit 717bfb5f46
2 changed files with 9 additions and 4 deletions
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2
include/linux/usb/audio-v2.h
View file

@ -170,6 +170,8 @@ struct uac2_as_header_descriptor {
__u8 iChannelNames;
} __attribute__((packed));
#define UAC2_FORMAT_TYPE_I_RAW_DATA (1 << 31)
/* 4.10.1.2 Class-Specific AS Isochronous Audio Data Endpoint Descriptor */
struct uac2_iso_endpoint_descriptor {

11
sound/usb/format.c
View file

@ -47,7 +47,7 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip,
int protocol)
{
int sample_width, sample_bytes;
u64 pcm_formats;
u64 pcm_formats = 0;
switch (protocol) {
case UAC_VERSION_1:
@ -63,14 +63,17 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip,
struct uac_format_type_i_ext_descriptor *fmt = _fmt;
sample_width = fmt->bBitResolution;
sample_bytes = fmt->bSubslotSize;
if (format & UAC2_FORMAT_TYPE_I_RAW_DATA)
pcm_formats |= SNDRV_PCM_FMTBIT_SPECIAL;
format <<= 1;
break;
}
}
pcm_formats = 0;
if (format == 0 || format == (1 << UAC_FORMAT_TYPE_I_UNDEFINED)) {
if ((pcm_formats == 0) &&
(format == 0 || format == (1 << UAC_FORMAT_TYPE_I_UNDEFINED))) {
/* some devices don't define this correctly... */
snd_printdd(KERN_INFO "%d:%u:%d : format type 0 is detected, processed as PCM\n",
chip->dev->devnum, fp->iface, fp->altsetting);