[alsa-devel] ASoC: fsl_sai: Has anybody attempted to run the i.MX6UL in TDM mode with channels > 2?

[Alexandre Belloni]

Hi Caleb,

Fabio pointed to that thread because I'm trying to use the i.mx7d SAI in
TDM mode with 8 channels (but I'm using only 4).

On 02/05/2016 at 10:52:39 -0700, Caleb Crome wrote :
> Hi all,
>    Now that the MX6 fsl_ssi seems to be getting stable for TDM with
> channels > 2 (thanks all!), the MX6 UL and MX7 have only the SAI port.
> 
> Does anybody have experience with running the SAI with more than 2 channels?
> 

I have a really small patch to make the SAI driver configure CR4 and CR5
properly for more than 2 channels.
Data on the TDM bus seems fine.

However, I have an issue with the sample ordering. Discussing that with
Lars, it seems the SDMA is getting confused when switching periods. To
test, I'm playing a 441Hz sine that is fading out. I can definitively
see block of 1024 samples (it is period_size) that are ok but not
properly ordered. You can have a look at:
http://free-electrons.com/~alexandre/playback.png

Did you have the same issue?

-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com