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iMX6q ESAI in slave mode, corrupted data, voltage levels?

Question asked by Sebastian Fett on Jan 23, 2017
Latest reply on Jan 26, 2017 by Sebastian Fett

Hello!

 

We're trying to use the ESAI interface on our iMX6q as 8 32bit slot per frame TDM at 96kHz. So with a bit clock of 24.576 MHz. Frame and bitclock are provided by an external codec.

 

We are able to play a 8ch audio file through aplay. But the data stream just stops for single slots or even several frames. 

On a first try in master mode the whole thing was working. 

 

We use a 4.1 linux kernel with the latest patches (up to 14-01-2016). So I would have expected some underrun detection in the fsl_esai driver (the check is running but never returns positive). 

 

On a 8ch file with only one channel with active data I can see the shifting described in errata008000, that is why I would have expected underruns. 

 

So my questions are:

Is there a differenc in master and slave mode that might explain the data dropouts?

Where can I find out where the bottleneck is? The DMA is burried deeply in the drivers. 

Do you know of any 8ch 96kHz TDM implementations on the iMX6q that work?

 

Attached you'll find some screenshots. 

 

Regards,

Sebastian

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