[alsa-devel] [PATCH] ALSA: usb-audio: Expose sample resolution through proc interface

[Takashi Iwai]

On Sun, 17 Feb 2019 23:17:21 +0100,
Jussi Laako wrote:
> 
> 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 at sonarnerd.net>

The code change looks but, just some minor issues:

> ---
>  sound/usb/card.h   | 1 +
>  sound/usb/format.c | 2 ++
>  sound/usb/proc.c   | 1 +
>  3 files changed, 4 insertions(+)
> 
> diff --git a/sound/usb/card.h b/sound/usb/card.h
> index ac785d15ced4..d9bb2c4a3bd9 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 */

Please use tabs.  checkpatch will catch such a problem, so please run
it at the next time before submission.


>  	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..d5b7cbcc2956 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 = (unsigned int) sample_width;

Such cast is superfluous in Linux kernel code.

I applied the patch with these fixed locally.


Thanks!

Takashi