HDMI output blinking back screen

Hello,
I encounter issue that ,after showing Nvidia logo, screen go black and starting to blink. It show terminal content, next black screen, again terminal and so on.
Attaching X logs
Xorg.0.log (17.1 KB)

Any hint ?

Your xorg log goes to close without any error. What is the result of your board with below command?

ps aux |grep gdm

I guess the result would be no such process is running.

If so, please run “xinit &” and then share me the Xorg log again.

I would also be interested to have you run “dmesg --follow”, and show what is logged as a result of the “xinit &” (dmesg will show a different log as the log is appended). If you can’t get a subset of that which is only during the Xorg log creation during xinit &, then just attach a full copy of the output of dmesg which ends after the GUI login fails. You might also mention if your login user is just a user, or if it is logging in as root (probably not, but it would be relevant).

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Hi
This is ps command result, at the same time the screen is blinking between terminal and black screen

$ ps ax | grep gdm
 5537 ?        Ssl    0:00 /usr/sbin/gdm3
 9598 ?        Sl     0:00 gdm-session-worker [pam/gdm-launch-environment]
 9619 tty1     Ssl+   0:00 /usr/lib/gdm3/gdm-x-session gnome-session --autostart /usr/share/gdm/greeter/autostart
 9621 tty1     D+     0:00 /usr/lib/xorg/Xorg vt1 -displayfd 3 -auth /run/user/120/gdm/Xauthority -background none -noreset -keeptty -verbose 3
 9710 pts/0    S+     0:00 grep --color=auto gdm

Hi I attached dmesg logs.
It looks like some issue with HDCP.
Continuous blanking/unbalnking HDMI.
dmesg.log (173.9 KB)

Could you stop your gdm3 process and do what I said in this comment?

Your issue should have nothing to do with HDCP because we don’t support HDCP at all.

To aid in stopping gdm3, you might try to do this on a command line (you can “CTRL+ALT+F2” (or F3 or F4) to get to a text console. Then run “sudo systemctl isolate multi-user.target”. This should disable the automatic login and automatic attempt at adding a GUI until you reboot or manually go back to (isolate) graphical.target mode. Or use serial console. I recommend the CTRL+ALT+F2 because this means you can leave serial console free to watch “dmesg --follow” (and this is a more convenient way to log).

Incidentally, a reason why you want to try manually running “xinit &” is purely as a debug tool…then your debug logs include only the X server messages and not the graphical login manager logs. If “xinit &” fails, then it will exit instead of restarting. As a result, you will be able to see what the X server itself gives as its reason for failing. There would likely be a new “/var/log/Xorg.0.log”, but the number (the “.0.”) might change. Right after you run any xinit & you can find the specific log via:
ls -ltr /var/log/Xorg.*.log | tail -n 1

You should also state what kind of monitor cable you have. Is this purely HDMI? Is there any kind of adapter involved?

I had to reflash my board so now I lost this issue.
Can we return to this topic again if issue will back?

The topic would be probably closed in about 14 days. You should file new topic if you hit again.

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