megi's PinePhone Development Log RSS

2021–05–22: PinePhone kernel news

There are a bunch of new notable things in my kernel since the last update 2 months ago. I've added some patches from others:

And I also continue to tune up and improve my and other drivers:

I've also done more power draw measurements a few weeks ago (that's where the before/after pictures linked above are from), and pinephone's power consumption in suspend is now around 60mW with modem off. Modem usually adds another 10–15mW. So with 11Wh battery, that means around 6 day standby, if that's all you do with the phone. :)

Overall 5.12 and 5.13 in my tree should be working quite well at this time! Samuel's time travel fix („clocksource/arm_arch_timer: Improve Allwinner A64 timer workaround“) seem to have solved the last stability issues I had with some of the pinephones I have access to. Things look pretty bright!

There are still some HDMI issues some people keep reporting, that manifest themselves by anx7688 firmware not getting past „DP status = 0×03“ (it should go from 0 all the way to 6 normally). When this happens it's caused by HDMI controller inside the SoC using incorrect clock frequency, and anx7688 fails to acquire the HDMI signal from the SoC. It should be easy to fix, but I have trouble reproducing it with my kernel and userspace, so I can't identify the root of the problem, yet.

I've also worked on musb DMA support, and I got quite far (my current work is here It seems that DMA controller works (I can see DMA completion interrupts getting triggered), but integration of DMA driver with mainline musb driver is a bit complicated, and the only documentation is the existing BSP code. Musb seemingly has nice abstraction for supporting various DMA drivers, until you look closer and realize that musb core has many code paths that change how things are done based on what DMA driver is used. So in the end the interface between musb core and DMA drivers is quite messy. :(