Custom device tree for supporting touchscreen in jetson Orin NX

Robotics & Edge Computing Jetson & Embedded Systems Jetson Orin NX
1

Hi all,

I have a 7 inch touchscreen with the following EDID

[00 ff ff ff ff ff ff 00 05 d7 00 00 00 00 00 00\
 ff 22 01 03 80 32 1f 78 07 ee 95 a3 54 4c 99 26\
 0f 50 54 00 00 00 01 01 01 01 01 01 01 01 01 01\
 01 01 01 01 01 01 c2 10 00 14 41 58 3c 20 74 0a\
 5a 08 14 bc 52 00 00 1e 00 00 00 fd 00 17 f0 0f\
 ff 0f 00 0a 20 20 20 20 20 20 00 00 00 fc 00 48\
 44 54 56 20 31 30 38 30 70 0a 20 20 00 00 00 00\
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 b2]

Do I have to only change the dcb blob ?

Note that, I have an IC on my customized carrier board to convert HDMI to TFT signaling.

2

Just to clarify first… you may need to describe more for what is your exact question and requirement.

I don’t see much point to give me an EDID and touch screen thing… Sounds not related to DCB either.

3

@WayneWWW thank you for your reply. Actually you’re right. I’m quite confused and overwhelmed and it’s pretty obvious from my question.

The goal is to see Ubuntu Desktop on my 7 inch touchscreen. Before this, I could drive HDMI port on my custom carrier board, and could see the Desktop on the monitor. Now I track the display configuration within the device trees and see display related config:

tegra234-p3768-0000+p3767-xxxx-nv-common.dtsi:

display@13800000 {
                /* os_gpio_hotplug_a is used for hotplug */
                os_gpio_hotplug_a = <&gpio TEGRA234_MAIN_GPIO(M, 0) GPIO_ACTIVE_LOW>;
                status = "okay";
        };

Also in another dts file, I have DCB value

overlay/tegra234-dcb-p3767-0000-hdmi.dts

/ {
        fragment-t234-dcb@0 {
                target-path = "/";
                __overlay__ {
                        display@13800000 {
                                nvidia,dcb-image = [
                                        55 aa 16 00 00 37 34 30 30 e9 4c 19 77 cc 56 49
                                        44 45 4f 20 0d 00 00 00 70 01 00 00 00 00 49 42
                                        4d 20 56 47 41 20 43 6f 6d 70 61 74 69 62 6c 65
                                        01 00 00 00 10 00 82 18 30 33 2f 31 36 2f 32 33
                                        00 00 00 00 00 00 00 00 21 18 50 00 e1 2b 00 00
                                        .....

At this point, I don’t know if I should change the content of nvidia,dcb-image or not ?

1 Like
4

Ok. Let me explain what I can directly guide and what I cannot teach here.

  1. The DCB image is basically for switching the display mode between DP and HDMI.
    You could actually refer to the board config file in your Linux_for_Tegra directory. Search the one with “p3509” as a prefix in the file name. This one has all the necessary change for enabling the HDMI.

  2. We don’t provide a existing solution for the “touch” function of a touch panel. Thus, I cannot guide you what to do in this part.

5

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