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Solution for issue with 'panfrost' module not initializing due to missing dependency - Printable Version

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Solution for issue with 'panfrost' module not initializing due to missing dependency - cobratbq - 12-02-2021

I have noticed that there have been reports of not getting 'panfrost' graphics acceleration working properly. I have problems myself recently with the installation of vanilla Debian Bullseye. I found that there is a hidden dependency on a kernel module that is not yet loaded during early boot, and will (probably by coincidence) be loaded late. Too late for 'panfrost' to initialize before Xorg starts. Consequently, Xorg starts with 'LLVMpipe' DRI display support. Basically, no graphics support.

In the case of Debian, (configuration works slightly differently in other distributions) I fixed this with a 'modprobe.d' config file:

Code:
softdep panfrost pre: governor_simpleondemand
Then run 'update-initramfs -u' to make the modprobe-config part of the early boot process. ('governor_simpleondemand' seems to be part of 'gpu_sched' which 'panfrost' depends on, but it won't pull in 'governor_simpleondemand' by default.)

I have not saved a copy of the error message. However, `dmesg` would repeatedly try to load 'panfrost' in the first few seconds of booting the linux kernel, and fail.

I would be able to get accelerated support if I manually remove and reload the 'panfrost' module, then restart the desktop manager (`lightdm` in my case).
Code:
glxinfo
would show 'LLVMpipe' support on boot. Then, after reloading and restarting desktop manager, it would show "Panfrost" support correctly.

Upon searching the web, I found some occurrences of these issues in various distros but without clear solutions. For me, this works as a solution, so I wanted to share it.

This solution works for me on Debian's 5.10 and 5.14 kernels.