Linux USB audio driver - sample code / link / documentation

Linux USB audio driver - sample code / link / documentation

[Ramya Desai]

Dear All,

I did not find a document for writing a USB audio driver under Linux
environment. Please let me know any sample driver / link / document
which describes about the USB audio driver under Linux environment.

Thanks and Regards,
Ramya.

Re: Linux USB audio driver - sample code / link / documentation

[Daniel Mack]

On 11/25/2010 01:51 AM, Ramya Desai wrote:
> I did not find a document for writing a USB audio driver under Linux
> environment. Please let me know any sample driver / link / document
> which describes about the USB audio driver under Linux environment.

As Clemens wrote, examining existing drivers in the kernel repository
(under sound/usb) might help you most. Just have a look how they
communicate with the hardware and how they set up the ALSA components
inside the kernel.

Is there any documentation for the chip you're writing the driver for,
about the USB protocol it uses etc? Are you sure it does not follow the
USB audio class specifications? Posting the output of 'lsusb -v' might
also help.


Daniel

Re: Linux USB audio driver - sample code / link / documentation

[Ramya Desai]

On Fri, Nov 26, 2010 at 1:53 AM, Daniel Mack <zonque@gmail.com> wrote:
> On 11/25/2010 01:51 AM, Ramya Desai wrote:
>> I did not find a document for writing a USB audio driver under Linux
>> environment. Please let me know any sample driver / link / document
>> which describes about the USB audio driver under Linux environment.
>
> As Clemens wrote, examining existing drivers in the kernel repository
> (under sound/usb) might help you most. Just have a look how they
> communicate with the hardware and how they set up the ALSA components
> inside the kernel.

Thank you very much for your reply.

I have gone through the sound/usb/* sources. However, I have also gone
through the sound/soc/* sources. There is a documentation about the
SOC implementation like platform driver, machine driver etc. The
documentation is available in Documentation/sound/alsa/soc. Is there
any documentation, like soc, for USB implementation?

Thanks and Regards,
Ramya.

Re: Linux USB audio driver - sample code / link / documentation

[Clemens Ladisch]

Ramya Desai wrote:
> I did not find a document for writing a USB audio driver under Linux
> environment. Please let me know any sample driver / link / document
> which describes about the USB audio driver under Linux environment.

The simplest sample driver is this one:
http://www.alsa-project.org/~clemens/ua1a.patch

If your device were class compliant, it would be supported by the
standard driver.


Regards,
Clemens

Re: Linux USB audio driver - sample code / link / documentation

[Ramya Desai]

On Fri, Nov 26, 2010 at 1:21 PM, Clemens Ladisch <clemens@ladisch.de> wrote:
> Ramya Desai wrote:
>> I did not find a document for writing a USB audio driver under Linux
>> environment. Please let me know any sample driver / link / document
>> which describes about the USB audio driver under Linux environment.
>
> The simplest sample driver is this one:
> http://www.alsa-project.org/~clemens/ua1a.patch

Thank you very much for your link.

However, the source is also available at sound/usb/misc/ua101.c. What
is the difference between sound/usb/misc/ua101.c and your patch (in
the above link)?

Thanks and Regards,
Ramya.

Re: Linux USB audio driver - sample code / link / documentation

[Clemens Ladisch]

Ramya Desai wrote:
> On Fri, Nov 26, 2010 at 1:21 PM, Clemens Ladisch <clemens@ladisch.de> wrote:
> > The simplest sample driver is this one:
> > http://www.alsa-project.org/~clemens/ua1a.patch
> 
> the source is also available at sound/usb/misc/ua101.c.

No, that is for a different device.  The UA-101 requires
synchronization between capture and playback stream; because
of this, the UA-1A's driver is somewhat simpler.

And there is no ALSA USB audio documentation.


Regards,
Clemens

Re: Linux USB audio driver - sample code / link / documentation

[Ramya Desai]

On Fri, Nov 26, 2010 at 3:25 PM, Clemens Ladisch <clemens@ladisch.de> wrote:
> Ramya Desai wrote:
>> On Fri, Nov 26, 2010 at 1:21 PM, Clemens Ladisch <clemens@ladisch.de> wrote:
>> > The simplest sample driver is this one:
>> > http://www.alsa-project.org/~clemens/ua1a.patch
>>
>> the source is also available at sound/usb/misc/ua101.c.
>
> No, that is for a different device.  The UA-101 requires
> synchronization between capture and playback stream; because
> of this, the UA-1A's driver is somewhat simpler.
>
> And there is no ALSA USB audio documentation.

Thanks again, Clemens.  I will post if I get any problem while
developing the driver.

Thanks and Regards,
Ramya.