[alsa-devel] Intel Cherry Trail -- No sound in linux

[Pierre-Louis Bossart]

On 12/12/15 2:25 AM, ZH Tu wrote:
> As Pierre suggestions:
>
> try to enable a DSP loopback to see if the data isn't garbled by the driver
> amixer cset "name='pcm1_out mix 0 pcm0_in" on
>
> But we all know that the stream path is power on automaticlly, so even I do the mixer setting, the pcm1_out wighet still is in power off state.
>
> So is there way to do the loopback?

You need to do this on top of regular playback/capture settings 
otherwise yes DAPM will not power anything.
You can also try to do a loopback inside of the codec, i used this 
recently to create a mic-to-speaker loopback/larsen and show that the 
speakers were functional.

>
> Now every time I do the test:
> aplay test.wav
>
> I get the error message:
> [drm:intel_pipe_update_end [i915]] *ERROR* Atomic update failure on pipe C (start=46633 end=46634)
>
> And there're no more errors.
>
>  From the message I guess the pipe used by intel drm is blocked, so as to the pipe used by SST firmware,   that's why I cannot get data from DACDAT pin.
>
> This bug confused me for  a long time,  can anyone give some suggestions?

Apart from a bad configuration related to HDMI, this seems mostly 
unrelated to codec link issues.