garbled screen with RPI4 on 5.10-rc2

[Lucas Nussbaum]

Hi,

On 05/11/20 at 16:19 +0100, Maxime Ripard wrote:
> On Tue, Nov 03, 2020 at 09:35:43PM +0100, Lucas Nussbaum wrote:
> > On 03/11/20 at 16:27 +0100, Maxime Ripard wrote:
> > > On Tue, Nov 03, 2020 at 03:33:03PM +0100, Stefan Schake wrote:
> > > > Your kernel command line from the initial post seems to already have a
> > > > 
> > > > video=HDMI-A-1:1920x1080M at 60
> > > > 
> > > > setting, and this will override any HDMI detection.
> > > 
> > > That's just for the initial framebuffer, X is then free to ignore that
> > > to change it if it feels like it (and it looks like it does from the logs)
> > 
> > Strange, since disable_fw_kms_setup=1 really fixes it (I checked again).
> > 
> > If you think it's worth debugging and I can help somehow, let me know!
> 
> Do you have any other display you could test with?

I tried with two TVs.
On an old one, I did not reproduce the problem.
On a more recent one, I could reproduce a slightly different issue:
during boot, the same garbled output appeared and then disappeared.
then, there was some corruption on the login screen. I uploaded a
video[0] and a photo of the login screen[1]. dmesg is at [2].

[0] https://people.debian.org/~lucas/tmp/rpi4-tv.mp4
[1] https://people.debian.org/~lucas/tmp/rpi4-login-screen.jpg
[2] https://people.debian.org/~lucas/tmp/dmesg-tv.txt

Again, adding disable_fw_kms_setup=1 made the issue disappear.

> I tried running the daily image you pointed at, but it looks like it's
> running a 5.9 kernel from simplefb, and with nothing to update in apt,
> how did you upgrade to that 5.10 kernel?

I built a kernel using the 5.10.0-rc2 tarball.
I put /boot and /lib/modules at
https://people.debian.org/~lucas/tmp/linux-5.10.0-rc2.tgz so you can
untar this on your machine and (hopefully) reproduce the problem.

Lucas