[PATCH v24 22/34] ALSA: usb-audio: Save UAC sample size information

Wesley Cheng
2024-08-01T01:28:18Z

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@quicinc.com>
---
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))) {