linux-kernel - Re: [PATCH v1 00/35] drm: Analog TV Improvements

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Date:   Fri, 26 Aug 2022 06:07:47 +0200
From:   Mateusz Kwiatkowski <kfyatek@...il.com>
To:     Maxime Ripard <maxime@...no.tech>,
        Noralf Trønnes <noralf@...nnes.org>
Cc:     Jernej Skrabec <jernej.skrabec@...il.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Jerome Brunet <jbrunet@...libre.com>,
        Samuel Holland <samuel@...lland.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Daniel Vetter <daniel@...ll.ch>, Emma Anholt <emma@...olt.net>,
        David Airlie <airlied@...ux.ie>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Kevin Hilman <khilman@...libre.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Phil Elwell <phil@...pberrypi.com>,
        linux-arm-kernel@...ts.infradead.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        linux-amlogic@...ts.infradead.org, dri-devel@...ts.freedesktop.org,
        Dom Cobley <dom@...pberrypi.com>
Subject: Re: [PATCH v1 00/35] drm: Analog TV Improvements

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:
>> Hi Mateusz,
>>
>> On Mon, Aug 22, 2022 at 10:57:26AM +0200, Mateusz Kwiatkowski wrote:
>>> 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.
>
>> Maxime
> Best regards,
> Mateusz Kwiatkowski