[Letux-kernel] Fixing Audio driver

Michael Mrozek EvilDragon at openpandora.org
Thu May 23 14:29:03 CEST 2019

Am Donnerstag, den 23.05.2019, 07:31 +0200 schrieb H. Nikolaus


> > Ignoring AESS for the moment (we can add that later), the setup of
> > the audio devices should be in the twl6040 driver file?
> Only the twl6040 audio devices are there.
> To throw our AESS patches out, you could git checkout the mainline
> twl6040 driver.
> This should also make the rogue null ports go away.

If that helps in getting bare audio to work until someone finds the
time to get AESS to work, then that's okay.

aTc made a quick test yesterday playing audio with software mixing
through the headset - and it took 1,5% CPU power.

So software mixing is not as bad as I feared and it would be good
enough for the beginning.

We don't need any advanced Bluetooth, LTE-Modem or other features at
the beginning, those can always be delivered later.

But we need working speakers and headsets (and the headset already

> > I expected them to be in the board files.
> > And the first step would be to create proper devices instead of
> > having the speakers on channel 3 and 4 of the headset port.
> As far as I understand you need AESS to make it different. So we
> either have the channel 3+4 thing or have to fix AESS. No way through
> the middle...

That wouldn't make any sense in my opinion.
According to the TWL6040 feature list, the chip has multiple stereo
outputs - not one output with four channels.

They even have different power drivers.

So why should the speakers be channel 3 and 4? 

That would be weird.

Here's the standard TWL6040 driver (for Android, not sure if it's
different than the Linux one):

I'm no dev as you know, but from what I can see there, the outputs of
the TWL are clearly defined here and routed to different output devices
(handsfree, etc.)

I don't see a reason why the speakers shouldn't get their own output
device even with a driver that doesn't use AESS.

As headset output is working fine and speaker output shouldn't be that
much different (both are analog outputs), fixing this weird channel
issue might be enough to have a basic working audio system on the Pyra.

> > Maybe that's also part of the reason they don't work properly - as
> > the
> > headset output works, and that's just a normal analog output as
> > well.
> > 
> > -- 
> > Greetings,
> > 
> > Michael Mrozek
> > 
> > -----------------------
> > OpenPandora GmbH
> > CEO: Michael Mrozek
> > 
> > Schäffbräustr. 11
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> > http://www.openpandora.de/
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> > -----------------------
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> > 
Mit freundlichen Grüßen,

Michael Mrozek

OpenPandora GmbH
Geschäftsführer: Michael Mrozek

Schäffbräustr. 11
85049 Ingolstadt
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