[Bug 2064370] Re: Blank screen after boot in raspberry pi 4

[Andre Ruiz]

I just found a usb flash key with my last installation (from a daily
image) from a few days ago, and it does not have a line for that
dtoverlay at all (neither fkms nor kms).

This line seems to have appeared on the official release.

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to software-properties in Ubuntu.
https://bugs.launchpad.net/bugs/2064370

Title:
  Blank screen after boot in raspberry pi 4

Status in software-properties package in Ubuntu:
  New

Bug description:
  
  I just flashed noble arm64+raspi image and booted it in my raspberry pi 4, and after initial rainbow screen kernel boots with 4 raspberries on the top and boot text appears as normal. But then, before it finishes booting, the screen goes blank.

  Image is ubuntu-24.04-preinstalled-server-arm64+raspi.img.xz
  downloaded at Apr/30.

  ubuntu at ubuntu:~$ uname -a
  Linux ubuntu 6.8.0-1004-raspi #4-Ubuntu SMP PREEMPT_DYNAMIC Sat Apr 20 02:29:55 UTC 2024 aarch64 aarch64 aarch64 GNU/Linux

  I know the system booted because I can access it over the network and
  I even plugged a usb-serial adapter in the uart GPIOs and from there I
  can see the boot does progress to completion and offers me a prompt
  where I can use the system normally. But the HDMI screen stays blank.

  The funny thing is that I have been trying daily builds for quite some
  time now and they used to work well, this is the first one that does
  this (the official release).

  After testing some config options I found that if I change
  "dtoverlay=vc4-kms-v3d" for "dtoverlay=vc4-fkms-v3d" in config.txt
  then it boots ok and the screen stays on (note the change from kms to
  fkms).

  I also tried appending ",cma-128" to that line (it is present on other
  lines -- like for pi3 and pi0 -- but not on this one), it does not
  help.

  I don't think the issue is with my monitor since it works well for a
  long time. Also I checked EDIDs, they are detected when using fkms but
  they are blank when using kms:

  With KMS:
  ubuntu at ubuntu:~$ edid-decode /sys/class/drm/card0-HDMI-A-1/edid 
  EDID of '/sys/class/drm/card0-HDMI-A-1/edid' was empty.

  With fKMS:
  ubuntu at ubuntu:~$ edid-decode /sys/class/drm/card0-HDMI-A-1/edid 
  edid-decode (hex):

  00 ff ff ff ff ff ff 00 49 f7 00 00 00 00 00 00
  01 1a 01 03 80 00 00 00 0a d7 a5 a2 59 4a 96 24
  ......
  (supressed)

  I do not use a graphical environment on this unit so I don't know the
  consequences of this change (to me it just fixes the issue, but I
  guess it was there for a reason).

  Let me know if you need any other information from the environment.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/software-properties/+bug/2064370/+subscriptions