[Letux-kernel] Fixing Audio driver

aTc atc at k-n-p.org
Thu May 23 21:34:56 CEST 2019

On 5/23/19 7:26 PM, H. Nikolaus Schaller wrote:

> I just took some minutes (well more) and installed letux-4.19.44 on the 2GB Pyra.
> And for me, sound works!

Same here, although it's a letux image with the 4.19.0 kernel.

> Well, not optimal , but it works. When playing an MP3 I get noise after
> ca. 10 seconds. But before that, music is crisp and loud and volumed
> damon works as expected. This was better with some older kernel, so
> it is a pure software issue.

I've been playing 4 channel wav files through aplay, sounds is great 
through both the speakers and headphone output.

I did have to disable the volumed, with it enabled the volume levels of 
the channels move about all over the place.

The values the volumed reads from the wheel seem to fluctuate wildly :
adding an echo $WHEEL to the volumed script gives :
852 412 372 667 389 312 922 757 581 410 636 469 957 559 650 895 935 315 
854 395 1183 356 639 738 326 467
(the average value does change when moving the wheel, so it's not 
reading some other device)

Also, setting the handsfree volume above 40 causes lots of distortion in 
the speakers.
Setting it to levels around 70 causes white noise to appear sometimes, 
which doesn't go away when lowering the volume. It does sometimes 
dissapear again when setting the volume higher, At which point it stays 
away when lowering the volume.

The right speakers doesn't seem to be making proper contact with the 
pads, and requires some pressure on the case before it'll make any sound.

Getting the same to work on PyraOS shouldn't be too difficult, although 
the main problem there is that Mate wants to use pulseaudio, which tries 
probing the nonexisting subdevices, and locks up the entire mate 
settings daemon. (or it's the setting daemon itself that probes them)

I think a simple alsa config can split 4 channel devices into 2 stereo 
ones, or copy the first two channels to the second pair. pulseaudio can 
probably handle that as well.

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