[Letux-kernel] AESS / Audio Driver for Pyra

Michael Mrozek EvilDragon at openpandora.org
Mon Oct 29 16:04:26 CET 2018

Am Montag, den 29.10.2018, 15:04 +0100 schrieb H. Nikolaus Schaller:


> > > > Well, do you know when firmware loading changed?
> > > > Because right now, it seems Kernel 4.16/4.17 broke the audio system even
> > > > without AESS and 4.16 also broke TILER.
> > > Are you sure? For me, 4.19-rc1 broke the TILER and it is fixed since 4.19-
> > > rc6.
> > > And I have not seen any difference between 4.15 and 4.16 for display.
> > At least with 4.15 it already shows and rotates the console output when
> > booting and that didn't work anymore with 4.17 (I'm not sure we've tested
> > 4.16).
> The key problem seems to be that nobody did look into that so far and try to
> find the reason. There was plenty of time (3 months per major release, i.e. ~9
> months).

Well, AFAIK, only zmatt really knows what's going on here.
He is aware of the issue (also the problem that TILER breaks 3D at the moment),
but at the moment, he seems pretty busy :(

So unless someone else has the time / mood to work himself into it, it will take
an unknown amount of time.

> > Maybe, but right now, 4.15 seems to work best for us, at least regarding
> > TILER and audio.
> So why not fix these on 4.19ff? Next Monday I expect we will see 4.20-rc1.

I'm perfectly fine if these issues are being fixed, but wo is going to do that?
That is the bigger issue.

> > Can these patches be applied to 4.15 as well or is that not possible?
> Everything is possible. It is just a matter of the energy needed and how
> much we can and want to invest.

Well, is it more complex to fix TILER of backport the changes you did to Letux?
It could also be that TILER broke because of a different configuration issue in
Letux (similar to the audio system you just posted about).

> Generally, I would prefer if there were a team that invests time to fix the
> small number of remaining bugs of the latest kernel, rather than backporting
> fixes to some kernel which is no longer maintained upstream and will be
> abandoned at some not too far future.

While it's nice to have a bleeding edge kernel, it's also more time consuming
keeping all your stuff working with future upgrades.

Especially if these kernel upgrades happen so often these days and literally
EVERYthing we have needs to be retested / reassured to be working.

And that's where we all lack manpower at the moment.
See the recent issues with TILER or Audio. And who knows what other new bugs
have been introduced.

So I think it's more important to decide to use ONE kernel which we'll work on,
and make it run perfect with all hardware.

This can also be Kernel 4.19, if you like.
(A normal Debian system still runs Kernel 4.9.0).

This stable kernel can be used for productive systems and all new versions being
worked on should be in testing / unstable until all issues have been ironed out.

At the moment it feels to me that you fix some things with each kernel version
but that new kernel versions introduces multiple new bugs - so we'll never have
a kernel where EVERYTHING simply works.

As you said yourself:
4.15 is missing some OTG / Charger fixes.
4.16 and later has broken audio (okay, fixed already) and TILER

There is not a single kernel we could use for delivery of the device so far.
If the OTG / Charger fixes had been applied to 4.15 and also the later in-
development kernels, then 4.15 would be ready for delivery.

But right now, not a simple kernel is fully usable.


Michael Mrozek

OpenPandora GmbH
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