On Fri, Aug 26, 2022 at 06:07:47AM +0200, Mateusz Kwiatkowski wrote:
> Hi Maxime, Noralf and everyone,
> 
> Just as a quick update. I isolated the issue to the power management subsystem.
> Unfortunately I know very little about the power management subsystem so
> I don't think I can help.
> 
> There are two alternative dirty ad-hoc hacks that get things working.
> 
> - Commenting out the pm_runtime_put() / pm_runtime_get_sync() calls in vc4_vec.c
> - Reverting this PR by Dom Cobley a.k.a. popcornmix:
>   https://github.com/raspberrypi/linux/pull/4639

We don't have that PR upstream, so that might be the explanation to why
you're seeing this and I don't. I'll look into this further and will
open an issue.

I can't see anything wrong with the pm_runtime use though.

> Either of these approaches makes VEC mode switching work again. Obviously
> neither is appropriate for a permanent solution.
> 
> I tried some random code permutations that came to my mind, like using the
> vc4_encoder callbacks (e.g. post_crtc_powerdown) instead of the standard
> enable/disable encoder callbacks, but to no avail.
> 
> Since the clocks and power management seem to be delegated to the firmware now,
> my guess is that this might be a firmware issue, but I can't really check all
> the firmware versions. It certainly crashes on the version currently available
> in Raspberry Pi OS repos, and on this one:
> https://github.com/raspberrypi/rpi-firmware/commit/4dde751. My Pi4 doesn't boot
> using any newer firmware, at least not from USB - I might try some SD card
> after the weekend.

Thanks for your testing

Maxime