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>

3 files changed, 4 insertions, 0 deletions

diff --git a/sound/usb/card.h b/sound/usb/card.h
index ac785d15ced4..79fa2a19fb7b 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -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 */
diff --git a/sound/usb/format.c b/sound/usb/format.c
index fd13ac11b136..3ee7d6f853b7 100644
--- a/sound/usb/format.c
+++ b/sound/usb/format.c
@@ -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... */
diff --git a/sound/usb/proc.c b/sound/usb/proc.c
index e80c9d0749c9..ef9190530fd2 100644
--- a/sound/usb/proc.c
+++ b/sound/usb/proc.c
@@ -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);
         }