OMAP4 Audio SPDIF (S/PDIF): Is there somewhere a Linux driver for SPDIF output?

GregoireGentil

Expert 2330 points

Hello,

Is there somewhere a Linux driver for OMAP4 SPDIF?

Thanks in advance,

Grégoire

over 14 years ago

0 Israel Cepeda over 13 years ago

TI__Expert 5515 points

Hi Gregoire,

Yes it is, SPDIF is tried to be supported using McASP port (sound/soc/omap/omap-mcasp.c), but as it is not something clients use to ask for, it could not be so much supported.

Personally I haven't try to use it yet.

0 GregoireGentil over 13 years ago in reply to Israel Cepeda

Expert 2330 points

Interesting. I see the file indeed. The problem is user-space. I don't see the file in an Ubuntu-compatible tree but I see it in an Android-compatible tree. Then, the question is if it will be / can be integrated in ti/common-open/audio/audio_hw.c

Grégoire

0 Israel Cepeda over 13 years ago in reply to GregoireGentil

TI__Expert 5515 points

If you mean by TI, I don't know what are the plans to support that at user space. My guess is that it is more up to the user/client who wants to integrate it to the prototype/product. All I see is that driver is there in case someone wants to use it.

0 GregoireGentil over 13 years ago in reply to Israel Cepeda

Expert 2330 points

Let me rephrase and be more precise:

- Having the kernel is a huge first step. And it's REALLY great. Thanks to TI.

- but kernel is only half of the job (or perhaps 2/3 depending how you want to count!). User-space is the rest.

If I consider the two main "interesting" OS options:

* Ubuntu. I don't see this driver in a Ubuntu-dedicated kernel tree but backporting would be possible. User space is probably simple and it's just a matter to have the magic alsa-set_ctrl command lines.

* Android. I see this driver in an Android-dedicated kernel tree. But Android user space sound is painful as it's in c and everything is hard-coded. And I believe that to support mcasp on Android, you would have to patch and add this feature in the Android userspace file that I referenced in my previous post.

0 Israel Cepeda over 13 years ago in reply to GregoireGentil

TI__Expert 5515 points

I haven't look into Ubuntu, but for android there is a device that supports spdif, you may want to look into device/samsung/tuna/audio/audio_hw.c, seems like they are sending raw PCM to the McASP port, but you should look also to the kernel they are using for that device in order to know more details because as I previously mention, this is not a common application for TI clients.

0 Radek Dostal over 13 years ago in reply to Israel Cepeda

Prodigy 10 points

Can you point me to the kernel location where you find out this SPDIF driver. I would like to port it to AM335x.

Thanks,

Radek

0 GregoireGentil over 13 years ago in reply to Radek Dostal

Expert 2330 points

Sorry for not replying earlier. The forum notification was in my spam folder. For instance, here:

http://omapzoom.org/?p=kernel/omap.git;a=blob;f=sound/soc/omap/sound/soc/omap/omap-mcasp.c;h=b7713a2844d0d3c9071ac89ce7a088e09b28c5dc;hb=HEAD

0 Bell Zhong over 12 years ago in reply to Radek Dostal

Prodigy 20 points

Hi Radek,

Have you ported the SPDIF driver to AM335x? We are working on a custom board based on AM335x, and aslo need such driver to enable SPDIF transmit.

Bell

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OMAP4 Audio SPDIF (S/PDIF): Is there somewhere a Linux driver for SPDIF output?