Additing a new Hardware Specific feature in the ALSA driver

Additing a new Hardware Specific feature in the ALSA driver

[SUBHRANIL CHOUDHURY]

Dear all,
I am new to ALSA  programming.
Suppose if i have to add some hardware specific feature in the ALSA sound
driver and expose to the application via the ALSA library, how can do that?

Please reply if you have some inputs.
Anything is welcome.
Thanks in advance.

Regards,
Subhranil

Additing a new Hardware Specific feature in the ALSA driver

[SUBHRANIL CHOUDHURY]

On Sat, Dec 20, 2008 at 7:41 PM, SUBHRANIL CHOUDHURY <subhra85@gmail.com>wrote:

>
>
> Dear all,
> I am new to ALSA  programming.
> Suppose if i have to add some hardware specific feature in the ALSA sound
> driver and expose to the application via the ALSA library, how can do that?
>
> Please reply if you have some inputs.
> Anything is welcome.
> Thanks in advance.
>
> Regards,
> Subhranil

Re: Additing a new Hardware Specific feature in the ALSA driver

[Eliot Blennerhassett]

SUBHRANIL CHOUDHURY wrote:
> Dear all,
> I am new to ALSA  programming.
> Suppose if i have to add some hardware specific feature in the ALSA sound
> driver and expose to the application via the ALSA library, how can do that?
>
> Please reply if you have some inputs.
> Anything is welcome.
> Thanks in advance.
>   
Please give more information about the kind of feature.
Standard alsa controls support arrays of integers, boolean, bytes or
enumerated lists of strings as controls.

Beyond that you can consider using the hwdep facility which basically
gives you a special device file which can implement your special file
operations  eg ioctl

regards

Eliot

Re: Additing a new Hardware Specific feature in the ALSA driver

[Eliot Blennerhassett]

SUBHRANIL CHOUDHURY wrote:
> Eliot,
> Suppose i need to change the DAC gain, ADC gain of the audio codec and
> also disable and enable AGC of the codec i need to put some IOCTLs in 
> the driver.
> So, in case of ALSA how do i implement those IOCTLs in the driver and
> also expose them to the application through the ALSA library.

No! For this kind of control You just need to implement standard alsa
controls in your driver.

BOOLEAN:  AGC ON/OFF
INTEGER: DAC gain.

See "writing an ALSA driver" for details, and study the source of any
ALSA driver.

http://www.alsa-project.org/~tiwai/writing-an-alsa-driver/c843.htm
--
Eliot