[PATCH v18 16/41] ALSA: usb-audio: Save UAC sample size information

[Wesley Cheng <quic_wcheng@xxxxxxxxxxx>]

Within the UAC descriptor, there is information describing the size of a
sample (bSubframeSize/bSubslotSize) and the number of relevant bits
(bBitResolution).  Currently, fmt_bits carries only the bit resolution,
however, some offloading entities may also require the overall size of the
sample.  Save this information in a separate parameter, as depending on the
UAC format type, the sample size can not easily be decoded from other
exisiting parameters.

Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
---
 sound/usb/card.h   | 1 +
 sound/usb/format.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/sound/usb/card.h b/sound/usb/card.h
index 2884912adc96..02e4ea898db5 100644
--- a/sound/usb/card.h
+++ b/sound/usb/card.h
@@ -15,6 +15,7 @@ struct audioformat {
 	unsigned int channels;		/* # channels */
 	unsigned int fmt_type;		/* USB audio format type (1-3) */
 	unsigned int fmt_bits;		/* number of significant bits */
+	unsigned int fmt_sz;		/* overall audio sub frame/slot size */
 	unsigned int frame_size;	/* samples per frame for non-audio */
 	unsigned char iface;		/* interface number */
 	unsigned char altsetting;	/* corresponding alternate setting */
diff --git a/sound/usb/format.c b/sound/usb/format.c
index 3b45d0ee7693..5fde543536a8 100644
--- a/sound/usb/format.c
+++ b/sound/usb/format.c
@@ -80,6 +80,7 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip,
 	}
 
 	fp->fmt_bits = sample_width;
+	fp->fmt_sz = sample_bytes;
 
 	if ((pcm_formats == 0) &&
 	    (format == 0 || format == (1 << UAC_FORMAT_TYPE_I_UNDEFINED))) {