[alsa-devel] Resend: Incorrect sbits for snd-usb-audio

[Sander Jansen]

On Sun, Dec 8, 2013 at 12:27 PM, Sander Jansen <s.jansen at gmail.com> wrote:

>
>
> On Sun, Dec 8, 2013 at 3:20 AM, Takashi Iwai <tiwai at suse.de> wrote:
>
>> At Fri, 6 Dec 2013 14:57:46 -0600,
>> Sander Jansen wrote:
>> >
>> > Hi,
>> >
>> > I had send this out earlier back in September, but never got a response.
>> >
>> > I have a Focusrite Scarlett 2i4 USB Audio Interface. The audio format
>> > exposed by ALSA for  this device is S32_LE. From the hardware specs and
>> > lsusb. it supposed to only have a 24 bit resolution (with the LSB bits
>> set
>> > to 0):
>> >
>> > AudioStreaming Interface Descriptor:
>> >         bLength                 6
>> >         bDescriptorType        36
>> >         bDescriptorSubtype      2 (FORMAT_TYPE)
>> >         bFormatType             1 (FORMAT_TYPE_I)
>> >         bSubslotSize            4
>> >         bBitResolution         24
>> >
>> > When I query the sbits for this device, I expect it to return 24, but
>> > instead it returns 32. Looking through the usb audio driver code, it
>> > doesn't look like this information is actually exposed to userspace. The
>> > 'parse_audio_format_i_type'  in usb/format.c merely returns the
>> supported
>> > formats, but doesn't include any msbits info. (and it doesn't look like
>> it
>> > can be easily changed to return the msbits info as well).
>> >
>> > Was this intentionally left out, or is this a missing feature in the
>> driver?
>>
>> It's just because of laziness because almost no applications check the
>> msbit but only the format type.  Feel free to send an enhancement
>> patch.
>>
>>
>>
> Thanks for the clarification. I may give that a shot.
>
> Sander
>
>
Forgive my ignorance, but to which git tree should this patch be developed
on?

git://git.alsa-project.org/alsa-kernel.git
https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/
?

Thanks,

Sander