[Letux-kernel] AESS / Audio Driver for Pyra

H. Nikolaus Schaller hns at goldelico.com
Mon Oct 29 15:04:08 CET 2018


> Am 29.10.2018 um 14:47 schrieb Michael Mrozek <EvilDragon at openpandora.org>:
> Am Montag, den 29.10.2018, 13:31 +0100 schrieb H. Nikolaus Schaller:
> Hi,
>>> 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).

>>> With 4.15, all this was still working fine - so if your patch would work
>>> with 4.15, I am thinking of using 4.15 for a release.
>>> Once it's out, we have more
>>> devs who can work on future kernel releases.
>> Just wait. Maybe, it is just one (missing?) patch which fixes audio for
>> 4.19...
> 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.

>> But beware: 4.15 has several bugs and missing features (e.g. charger, OTG
>> mode, etc.) that have been fixed between 4.16 and 4.19.
> Have these all fixed by you or upstream?

I refer to our Letux changes for all those components that are not supported
by upstream kernel. Some rely on or were required by upstream changes.

> 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.

If someone invests additional time to backport and test the Letux specific
patches, you can stay with 4.15 and get it to same feature level.

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fixes to some kernel which is no longer maintained upstream and will be abandoned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.

So it is just double-work to speed thing up a little (if at all since I can't
estimate what goes faster: backporting important things of fixing the remaining


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