HDMI related register adjustment

To improve the HDMI eye pattern, we are trying to adjust the registers according to the “Jetson Orin NX Series and Jetson Orin Nano Series Tuning and Compliance Guide.”
Of the registers in Table 15, 0x1380c118 and 0x1380c120 were able to be adjusted.
However, 0x1380c14c cannot be adjusted due to “Bus error”.
Is there any setting required to adjust 0x1380c14c?

[2023-11-28 08:48:02.496] sudo devmem2 0x1380c118
[2023-11-28 08:48:03.074] /dev/mem opened.
[2023-11-28 08:48:03.074] Memory mapped at address 0xffffab80b000.
[2023-11-28 08:48:03.074] Value at address 0x1380C118 (0xffffab80b118): 0x0
[2023-11-28 08:48:03.077] root@jetson:/tmp/hdmi# sudo devmem2 0x1380c120
[2023-11-28 08:48:06.819] /dev/mem opened.
[2023-11-28 08:48:06.819] Memory mapped at address 0xffff86c26000.
[2023-11-28 08:48:06.819] Value at address 0x1380C120 (0xffff86c26120): 0x0
[2023-11-28 08:48:06.821] root@jetson:/tmp/hdmi# sudo devmem2 0x1380c14c
[2023-11-28 08:48:09.650] /dev/mem opened.
[2023-11-28 08:48:09.650] Memory mapped at address 0xffff8a9ca000.
[2023-11-28 08:48:09.932] Bus error
[2023-11-28 08:48:09.932] root@jetson:/tmp/hdmi#

Please refer to this document to adjust HDMI register.


Thank you for answering

Is it possible that this is related to not applying the patch fix described in section 4.2.3 of “NVIDIA Jetson Linux Release Notes Version 35.4.1 GA”?

This is related to the answer above. Please tell me the specific parameters to set it to HDMI mode.


Let me explain this again

  1. if you didn’t apply any patch as this post is doing, then your board are not using HDMI mode at all but still in DP mode. The DP mode can work fine with HDMI but 4k will have problem.
    AGX Orin Display issue with 4K HDMI - #4 by vbhm

A quick method to check the mode is running

export DISPLAY=:0

If your mode is DP, it will show “DP-0”.

  1. The tuning guide is only for HDMI mode.

Shows the execution results of the “export” command.

jetson@jetson:~$ export | grep DISPLAY
declare -x DISPLAY=“:1”
jetson@jetson:~$ xrandr --listmonitors
Monitors: 1
0: +*HDMI-0 1920/509x1080/286+0+0 HDMI-0

It is working in HDMI mode, but DISPLAY=“:1” instead of DISPLAY=“:0”.
Is the problem caused by the DISPLAY=“:1” setting?
In that case, please tell me the procedure to change DISPLAY=“:0”.


What is the result of

sudo busybox devmem 0x1380c14c

sudo busybox devmem 0x1380c14c

I was able to adjust the register by executing this command.
thank you.

What is the difference between “devmem2” and “busybox devmem”?

Thank you very much for everything.

actually devmem2 shall also work if you adjust the read size.

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