2024–02–24: Some upstreaming and Pinephone Pro modem audio

I've been working on upstreaming a bunch of patches for Pinephone (Pro):

Pinephone Pro camera lens control driver was sometimes returning errors during probe – a simple timing issue, accepted upstream
I've pushed magnetometer driver used on Pinephone (and Pro) through 4 revisions – it looks like all issues were addressed, and will be accepted soon (Andrey Skvortsov is also working on U-Boot change that will detect which magnetometer is used on the particular Pinephone batch, and will enable the appropriate one)
Fix for Pinephone A64 SoC's display engine blender bugs – this is a long standing issue with A64 display engine, where you can confuse the driver into disabling DRM planes that should be enabled if you use userspace app that uses planes extensively. All patches passed review at first try, so it'll probably get accepted soon, too.
Support for jack detection/headset buttons on Pinephone, originally by Arnaud Ferraris – this didn't pass the initial review and needed pretty much a complete rewrite of original patches. It will probably not pass the second round either, because of required DT bindings changes. If I'll be forced to drop the bindings changes, the Pinephone will need a special sound card driver, instead of using gerneic simple-sound-card one. I'll not write one anytime soon, so this may still need a small set of very simple patches in my kernel branch for it to work with simple-sound-card. Anyway, I expect most of the codec changes to get accepted.
LED controller for Pinephone Pro flash LED fixes – this is a simple resource management issue, the patch got accepted
Stuck power key on Pinetab 2 when doing resume from suspend – similar issue to the one on original Pinephone, the patch got accepted
Fix for USB host mode not working on Pinephone/Pinebook Pro and possibly elsewhere since v6.6 – got accepted
Add support for higher resolution in rkisp1 driver for RK3399 (Pinephone Pro IMX258 sensor max resolution) – I got rejection on earlier version, this will probably get accepted
Some audio speed playback bug related to clock unit of RK3399 (Pinephone Pro) when switching between 44.1/48kHz sample rate – no reaction, yet
MIPI-DSI clock speed calculation improvements for non-burst video transmission modes (required for Pinephone Pro panel 60Hz fix) – no reaction, yet

There are also large changes in my kernel tree branches organization starting with orange-pi-6.8. The branches are split up differently and more finely. So there are a lot more individual branches that make up orange-pi-6.8 integration branch.

I support/develop for about 14 different boards in my kernel, so if you're interested in just Pinephone you'll have much easier time just merging a subset of branches into your own integration branch, if you don't like having other changes I carry in my kernel tree, in your kernel build.

The orange-pi-6.8 branch now looks pretty good, and I'm already using it regularly on some of my SBCs and on Pinebook Pro.

Pinephone Pro modem audio work

I've managed to create a setup for passing audio between modem's codec and the main codec in the best possible quality. S/N ratio is very good (> 80dB at the very least), and I managed to understand and get rid of sources of the apparent distortion in the signals that I was getting before.

I've made it so both directions use differential signalling at maximum possible signal amplitude to improve the S/N ratio. There's also no apparent interference from the other noise going on on the PCB, according to my tests of this setup.

I'm still working on the main codec audio routing setup to be able to connect the modem signals to mic and earphone properly.

I'll be publishing all my findings on this, including my audio routing setup tools for both codecs, soon. A small patch to the modem SDK will be needed. The „patch“ is applicable over adb access to the modem.

I'll also do some testing on audio issues that may arrise after suspend/resume cycle, because I got reports that there are problems with that.