[PATCH v2 0/6] drm/vc4: kms: Misc fixes for HVS commits

[Jian-Hong Pan]

Maxime Ripard <maxime at cerno.tech> 於 2021年11月18日 週四 下午6:40寫道：
>
> On Thu, Nov 18, 2021 at 02:42:58PM +0800, Jian-Hong Pan wrote:
> > Maxime Ripard <maxime at cerno.tech> 於 2021年11月17日 週三 下午5:45寫道：
> > > The conversion to DRM commit helpers (f3c420fe19f8, "drm/vc4: kms: Convert to
> > > atomic helpers") introduced a number of issues in corner cases, most of them
> > > showing themselves in the form of either a vblank timeout or use-after-free
> > > error.
> > >
> > > These patches should fix most of them, some of them still being debugged.
> > >
> > > Maxime
> > >
> > > Changes from v1:
> > >   - Prevent a null pointer dereference
> > >
> > > Maxime Ripard (6):
> > >   drm/vc4: kms: Wait for the commit before increasing our clock rate
> > >   drm/vc4: kms: Fix return code check
> > >   drm/vc4: kms: Add missing drm_crtc_commit_put
> > >   drm/vc4: kms: Clear the HVS FIFO commit pointer once done
> > >   drm/vc4: kms: Don't duplicate pending commit
> > >   drm/vc4: kms: Fix previous HVS commit wait
> > >
> > >  drivers/gpu/drm/vc4/vc4_kms.c | 42 ++++++++++++++++-------------------
> > >  1 file changed, 19 insertions(+), 23 deletions(-)
> >
> > I tested the v2 patches based on latest mainline kernel with RPi 4B.
> > System can boot up into desktop environment.
>
> So the thing that was broken initially isn't anymore?

No.  It does not appear anymore.

> > Although it still hit the bug [1], which might be under debugging, I
> > think these patches LGTM.
>
> The vblank timeout stuff is a symptom of various different bugs. Can you
> share your setup, your config.txt, and what you're doing to trigger it?

I get the RPi boot firmware files from raspberrypi's repository at tag
1.20211029 [1]
And, make system boots:
RPi firmware -> U-Boot -> Linux kernel (aarch64) with corresponding DTB

The config.txt only has:
enable_uart=1
arm_64bit=1
kernel=uboot.bin

This bug can be reproduced with es2gears command easily.  May need to
wait it running a while.

Mesa: 21.2.2
libdrm: 2.4.107
xserver/wayland: 1.20.11  Using wayland

This bug happens with direct boot path as well:
RPi firmware -> Linux kernel (aarch64) with corresponding DTB

I tried with Endless OS and Ubuntu's RPi 4B images.
An easy setup is using Ubuntu 21.10 RPi 4B image [2].  Then, replace
the kernel & device tree blob and edit the config.txt.

[1] https://github.com/raspberrypi/firmware/tree/1.20211029/boot
[2] https://ubuntu.com/download/raspberry-pi

Jian-Hong Pan

> > [1] https://bugzilla.kernel.org/show_bug.cgi?id=214991
> >
> > Tested-by: Jian-Hong Pan <jhp at endlessos.org>
>
> Thanks!
> Maxime