On 8/29/24 21:40, Wesley Cheng wrote:
> 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
> existing 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 23d9e6fc69e7..15cda1730076 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))) {
Should this patch be added first? I mean, I don't see any dependency on
USB offload
I am actually confused as to how the regular USB audio path deals with
format, this must be inferred somewhere from the fmt_bits. Probably a
question for Takashi :-)
