I have 2 Jetson Nano Developer Kit model B01 4GB RAM (for simplicity in this topic I will refer to them as the “B01 board”), I have noticed the following:
(before starting: both B01 boards were powered with a very well power supply capable of 5V/4A output, test done with a 4K monitor and a 4K TV)
When the B01 board connected to the 4K monitor (this monitor supports up-to 4K@60FPS resolution: 60FPS when using DisplayPort DP only but when using HDMI cable it supports up-to 4K@30FPS only):
1- 4K monitor connected through DP: (60FPS supported) everything is ok.
2- 4K monitor connected through HDMI cable (both the monitor and the cable are working very well for 4K@30FPS when tested with another device to remove any possibility of hardware issues):
a- at boot: Nvidia logo appears for a very short period of time then everything goes black.
b- the screen tries to scan for input signal but nothing found and it turns off.
c- forced the screen to keep scanning nothing appears on the screen yet and no HDMI signal detected from the B01 board.
d- connected it back to DP everything works fine.
3- B01 board connected to 4K TV that supports only 4K@30FPS (no DisplayPort DP available, only HDMI): everything works fine
now my conclusion is:
- the B01 board is trying to connect to the monitor using its maximum capability (4K@60FPS) when it is connected to HDMI/DP (while actually the screen does not support 60FPS in HDMI mode and will turn off when overloaded since it cannot process the incoming signal). this monitor may reports it supports 60FPS but for DisplayPort DP not for HDMI.
- when I force the monitor resolution to 4K@30FPS the screen starts to work fine, but the problem is at boot the screen seems to be getting 60FPS signal again from the B01 board so it will turn off since it can’t handle this high FPS. and since I have some experience with linux I tried the following:
-boot the B01 board
- wait until it finishes booting.(small wait time) at this moment the screen is black (nothing displayed just Nvidia Logo for a very short period of time)
- now theoretically the B01 finished booting and waiting for the user to login
- blindly: (click enter) that activates the current user password field
- blindly write the password and [click enter]: (that would login the current user)
- then the screen turns on and works normally (since I have previously set the resolution for my user at 4K@30FPS).
so now to recap:
- the issue is: when connecting the B01 board to my 4K monitor that supports up-to 60FPS (DP) and 30FPS (HDMI) it seems the B01 board will try to output 4k@60FPS without taking into account if it is connected through DP or HDMI cable.
- if we can force the resolution to be capped to 4K@30FPS or maybe safer FHD@30FPS during the “first-Boot” process then use the user defined values after booting and changing them.
PS: this is tested on a 4K monitor but maybe this will also happen with any screen with 2 different frame rates support for DP and HDMI (like: FHD@60FPS for DP and FHD@30FP for HDMI if exist)
This may help someone else facing the same issue to have a starting point to solve the issue.
I hope that Nvidia could help solving this issue, I am sure they have a better solution than my suggested possible solution above.