IMX8m Mini Same audio stream out multiple SAI data lines

[injaneer1]

Our board has 2 codecs to drive either left/right or tweeters/woofer.  The two codecs are wired to SA1_TX0 and SA1_TX1.  I have already created codec and platform drivers and have all this working.  I am able to transmit audio to the first codec on SA1_TX0.  I am trying to configure and setup so we send the same audio (2 channel) to both the SA1_TX0 and SA1_TX1 lines.

I have found in the fsl_sai.c file where the channels are pins are calculated based off the slots/channels.  The only way I have been able to enable the SA1_TX1 pin, is by telling the driver I have 4 channels of audio (which we do not). This causes both lines to work, but with only 2 channel audio, it is stop/go as you would imagine.

Is it possible to have the same audio going to two different TX pins on one SAI ?  And if so, how is this accomplished.

Thanks,

Chris

[injaneer1]

Ok,

I finally got this working. I had to setup the audio policy as QUAD mode instead of stereo then add a check for that under the primary output to force the correct channels and channel max. Then using the mentioned copy mode like for 5.1 and 7.1 created a dual stereo or 2.2 output mode.

If anyone needs this, just let me know.

[injaneer1]

Can anyone help with this topic ?

[jamesbone]

Are you using ALSA to perform this task?  if not, you need to remember that the i.MX device has an AudioMux  module that need to be configure and we recommend to use the Linux BSP + ALSA to handle the codecs

[injaneer1]

We are using Also in Android 10.  Can you share the configuration for the AudioMux to accomplish the same audio on two data lines on the same SAI.

Thanks,

[jamesbone]

You can take a look into the following application note, it is from an i.MX6, but it is the same module an apply for the i.MX8

http://www.nxp.com/docs/en/application-note/AN4952.pdf 

[injaneer1]

I do not see how t his document is relevant.  This does not describe using Alsa audiomux.  I am using SAI1 data lines 0 and 1, so they have the same bit and word clocks so there is no 2nd clock to configure ?

[injaneer1]

I have found this post, and it seems I am running in the correct mode of 10 for FCOMB, but do not get the results I see in this diagram under C ?

https://community.nxp.com/t5/i-MX-RT/How-can-I-configure-multi-channel-SAI-using-edma/m-p/968632