[BUG][MTL-002] Recorded file from echo-reference dev has distortion and noise

[yongzhi1]

Describe the bug
Run echo ref unit test with NOCODEC config, the captured file shows distortion and noise when examined on Audacity.

To Reproduce
Start playback first:

aplay -Dhw:0,0 -c2 -r48000 -fS16_LE /home/sample.wav

Run capture and check the captured file on desktop:

arecord -Dhw:0,13 /home/loop.wav -c2 -r48000 -fs16_le -d10 

Reproduction Rate
100%

Expected behavior
The issue is not reproducible with closed src ACE FW.

Impact
What impact does this issue have on your progress (e.g., annoyance, showstopper)

Environment

1. Branch name and commit hash of the 2 repositories: sof (firmware/topology) and linux (kernel driver).
   • Kernel: https://github.com/bardliao/linux/commits/echo-reference-nocodec
   • SOF: https://github.com/thesofproject/sof/tree/mtl-002-drop-stable
2. Name of the topology file
   • Topology: https://github.com/bardliao/sof/commits/test-echo-reference-nocodec-2

3. Name of the platform(s) on which the bug is observed.
   • Platform: MTL-RVP

Screenshots or console output
mtrace-echo-ref-mtl-002.txt
https://user-images.githubusercontent.com/19287706/203658196-f7212407-3407-497d-b893-ab293443ce5d.mp4

[lgirdwood]

Run echo ref unit test with NOCODEC config, the captured file shows distortion and noise when examined on Audacity.

@yongzhi1 can you take a screenshot of the audacity waveform and also attach a small raw PCM clip. Compressed audio cant be used to root cause distortion.

[yongzhi1]

Hi @lgirdwood, here is the screenshot for the waveform, the lower track was captured with ACE, in both cases LR_48k.wav was used

And the captured file loop-mtl-002.zip

[lgirdwood]

@kfrydryx @mengdonglin sounds like some clipping/distortion on the signal. Does not look like a DMA issue, but maybe format conversion or signal clipping in the copier ?

[mengdonglin]

@yongzhi1 @kfrydryx @lgirdwood Deprioritize this issue after sync with @bardliao . Current driver support for echo-reference is a temporary solution, and is being re-implemented. Let's test the new implementation when it's ready. Thanks!

[keqiaozhang]

Will test EC in new implementation when it's ready, closing this one.