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ALSA: usb-audio: Expose sample resolution through proc interface 

At least some USB devices use (MSB-aligned) audio format larger
than the actual resolution of the device. In order to expose the
actual device resolution (bBitResolution), add extra field to the
procfs stream info interface.

Signed-off-by: Jussi Laako <jussi@sonarnerd.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Jussi Laako 2019-02-18 00:17:21 +02:00 committed by Takashi Iwai
parent a06702ca02
commit c7a1326491
3 changed files with 4 additions and 0 deletions
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1
sound/usb/card.h
View File

@ -14,6 +14,7 @@ struct audioformat {
u64 formats; /* ALSA format bits */
unsigned int channels; /* # channels */
unsigned int fmt_type; /* USB audio format type (1-3) */
unsigned int fmt_bits; /* number of significant bits */
unsigned int frame_size; /* samples per frame for non-audio */
int iface; /* interface number */
unsigned char altsetting; /* corresponding alternate setting */

2
sound/usb/format.c
View File

@ -87,6 +87,8 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip,
}
}
fp->fmt_bits = sample_width;
if ((pcm_formats == 0) &&
(format == 0 || format == (1 << UAC_FORMAT_TYPE_I_UNDEFINED))) {
/* some devices don't define this correctly... */

1
sound/usb/proc.c
View File

@ -109,6 +109,7 @@ static void proc_dump_substream_formats(struct snd_usb_substream *subs, struct s
if (subs->speed != USB_SPEED_FULL)
snd_iprintf(buffer, " Data packet interval: %d us\n",
125 * (1 << fp->datainterval));
snd_iprintf(buffer, " Bits: %d\n", fp->fmt_bits);
// snd_iprintf(buffer, " Max Packet Size = %d\n", fp->maxpacksize);
// snd_iprintf(buffer, " EP Attribute = %#x\n", fp->attributes);
}