Sound Driver Querry

Sound Driver Querry

[Ajay Jain]

Hi,

I have already placed this question on the arm-linux-kernel mailing
list, but I was redirected here.

We have two different ARM based proprietary boards, one with a
"WM8751" audio codec and the other with a "WM9712" codec. The first
one supports only the "AIL" (specifically I2S) format, whereas the
second one supports both "AC97". We have an existing "OSS" audio
driver for the second one, based on the "AC97" and we use the
"AC97_codec.c" for the same. Now we also want to support the first
one, but since it does not have an AC97 support, I was looking for an
"AIL-I2S" support in the oss directory of the kernel. I do not seem to
find any mention of AIL/I2S/WM8751.

1. Is this chip/format supported in OSS?
2. Is this chip/format supported in the new ALSA?
3. Can somebody tell me about an OSS mailing list for developers. I
was on their website, but it does not have any such mention.

Does it effectively mean that I will have to shift to the new ALSA (Is
this chip/format supported ??) ?

Thanks.
~

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Re: Sound Driver Querry

[Liam Girdwood]

On Thu, 2006-12-28 at 12:40 +0530, Ajay Jain wrote:

> 
> We have two different ARM based proprietary boards, one with a
> "WM8751" audio codec and the other with a "WM9712" codec. 

What arm cpu are you using ?

> The first
> one supports only the "AIL" (specifically I2S) format, whereas the
> second one supports both "AC97". We have an existing "OSS" audio
> driver for the second one, based on the "AC97" and we use the
> "AC97_codec.c" for the same. Now we also want to support the first
> one, but since it does not have an AC97 support, I was looking for an
> "AIL-I2S" support in the oss directory of the kernel. I do not seem to
> find any mention of AIL/I2S/WM8751.
> 

You may be interested in the ASoC code here:-

http://opensource.wolfsonmicro.com/~lg/asoc/

ASoC basically abstracts out SoC cpu digital audio interfaces and has
architecture independent codec drivers. It also has very aggressive
dynamic audio power management.

Currently, we have platform support for pxa2xx, AT91xxx and S3C24xx
(alpha atm). Work is in progress for i.MX21/31.

> 1. Is this chip/format supported in OSS?
> 2. Is this chip/format supported in the new ALSA?

The WM8751 is currently not supported in ASoC, although it would take
about 2 days effort to add it.

> 3. Can somebody tell me about an OSS mailing list for developers. I
> was on their website, but it does not have any such mention.
> 

OSS audio is deprecated in the Linux 2.6 kernel.

> Does it effectively mean that I will have to shift to the new ALSA (Is
> this chip/format supported ??) ?
> 

Yes.


Liam



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Re: Sound Driver Querry

[Ajay Jain]

> What arm cpu are you using ?

We are using an ARM926-EJS. The interface between the code chip and
the cpu, is by our own proprietary I2C controller. Is it possible for
us to integrate this?
BTW, the patch you just mentioned, is that not in the main line
2.6.latest? We are using a 2.6.14, so is it possible to backport it?

> OSS audio is deprecated in the Linux 2.6 kernel.
Ok, but we have a working & robust AC97 WM9712 driver for the same. It
would be much more convenient for us if we have something similar in
OSS. So is this guy (the WM8751), supported in any form in the OSS?

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Re: Sound Driver Querry

[Liam Girdwood]

On Fri, 2006-12-29 at 17:46 +0530, Ajay Jain wrote:
> > What arm cpu are you using ?
> 
> We are using an ARM926-EJS. The interface between the code chip and
> the cpu, is by our own proprietary I2C controller. Is it possible for
> us to integrate this?

Yes, providing you create a Linux i2c driver for you controller. 

> BTW, the patch you just mentioned, is that not in the main line
> 2.6.latest? We are using a 2.6.14, so is it possible to backport it?
> 

It is, although I would recommend upgrading your kernel version as
2.6.14 is quite old.

> > OSS audio is deprecated in the Linux 2.6 kernel.
> Ok, but we have a working & robust AC97 WM9712 driver for the same. It
> would be much more convenient for us if we have something similar in
> OSS. So is this guy (the WM8751), supported in any form in the OSS?

Sorry, afaik no.

Liam


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Re: Sound Driver Querry

[James Courtier-Dutton]

Ajay Jain wrote:
>> What arm cpu are you using ?
> 
> We are using an ARM926-EJS. The interface between the code chip and
> the cpu, is by our own proprietary I2C controller. Is it possible for
> us to integrate this?

I2C interfaces (for codec control, not audio samples) are very simple, 
so supporting that should be quite easy.
It depends what is connected to the I2C interface. If it is just the 
codec, then you can write some simple ALSA specific code. If it also 
links to other I2C devices on the same bus, then you should implement 
support for it via the Linux Kernel I2C bus.

> BTW, the patch you just mentioned, is that not in the main line
> 2.6.latest? We are using a 2.6.14, so is it possible to backport it?
> 
>> OSS audio is deprecated in the Linux 2.6 kernel.
> Ok, but we have a working & robust AC97 WM9712 driver for the same. It
> would be much more convenient for us if we have something similar in
> OSS. So is this guy (the WM8751), supported in any form in the OSS?
> 

Do you have the I2S interface already working?
The WM9751 might default to some sensible register values, so purely 
sending audio samples to the I2S interface might be enough to get your 
sound out.

James

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