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

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.

Best regards,
Mateusz Kwiatkowski

W dniu 25.08.2022 o 18:17, Mateusz Kwiatkowski pisze:

Hi Maxime,

W dniu 25.08.2022 o 17:55, Maxime Ripard pisze:

quoted

Hi Mateusz,

On Mon, Aug 22, 2022 at 10:57:26AM +0200, Mateusz Kwiatkowski wrote:

quoted

Hi Maxime,

I tried testing and reviewing your changes properly over the last weekend, but
ultimately ran into this ("flip_done timed out" etc.) issue and was unable to
mitigate it, at least so far. This seems to pop up every time I try to change
modes in any way (either change the TV norm, or just try doing
"xrandr --output Composite-1 --off" followed by bringing it back on; it also
means that the Pi goes unusable when the DE's screen saving routine kicks in).

I'm using a Pi 4, and it works with the rpi-5.13.y branch
https://github.com/raspberrypi/linux, but seemingly nothing newer.
I specifically tried rpi-5.14.y, rpi-5.15.y and rpi-5.19.y - rpi-5.15.y,
which is the current main branch in Raspberry Pi OS, seems to be broken since
forever; at least since my patches (originally written for 5.10) landed there.

I'll try identifying the issue further, possibly later today, and maybe check
the rpi-6.0.y branch as well.

I've tried it this, and I can't reproduce it here. But I'm curious, how
did you apply this series? rpi-5.13.y is probably full of conflicts
everywhere?

I applied your patches onto rpi-5.15.y. There were conflicts, but they seemed
relatively minor. I'm not sure if I did a good job at resolving them - I ran
into various problems trying to test your changes, but I chose not to criticize
you before making sure that it's really due to your changes, or without some
remarks more constructive than "doesn't work" ;-)

I can push my rebase onto some Github fork if you're interested.

I was able to work around some of those problems, and also saw that some
of them were already mentioned by other reviewers (such as the generic modes
not matching due to the aspect ratio setting).

Ultimately I got stuck on this bug, so I put testing this series on hold
in favor of debugging the bigger issue. So far unfortunately no luck with it.

I did not try rebasing your changes onto 5.13 or older.

quoted

Maxime

Best regards,
Mateusz Kwiatkowski

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