Jetson Nano Screen resolution

Autonomous Machines Jetson & Embedded Systems Jetson Nano
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1

Hello,
We have design custom carrier board for Nvidia Jetson Nano SOM.
Priliminary all the interfaces work fine.
But in detail we are facing some issue, out of that one is with HDMI out port.
As priliminary we are getting display output on HDMI port but that is restricted to 1280x720 resolution only.
Same SOM if I put in Nvidia Devkit then it gives resolution upto 1920x1080.
Also after booting following message displayed on the screen.
After booting initially we got 1920x1080 resolution for some time but after that screen goes blank and display tunned to 1280x720 resolution.
I have doubt on following to two hardware points,

  1. Length of HDMI bus tracks from SOM to HDMI connector is almost 120mm.
  2. Also for HDMI differential pairs we have to maintain 100ohms impedance but actually it shows around 90ohms.
    Is these are the reasons that make Nano tune to lower resolution? or is there any software issue?
    Please guide me on this.
    With regards,
    Rahul.
    NvidiaScreenResolution
    NvidiaScreenResolution1000×562 213 KB
3

Hi, per your description, it looks more like a routing problem. Have you check your PCB design to follow the HDMI part in Nano Design Guide in DLC well? There are requests of trace length, impedance and spacing. Also you can run HDMI test based on tuning application doc in DLC.

4

Hi,
Thanks a lot for reply.
One more thing I want to mention here that along with HDMI port I have given Display port also and that is perfectly working fine with 1920x1080 resolution.
Even in HDMI port also initially it work on 1920 x1080 resolution and after sometime it switch to 1280x 720 resolution.
I think there might be setting where we can keep default resolution of 1080p.

6

Hi,

Could you share below info when this random issue happened?

  1. When 720p shows up, please dump dmesg.

  2. When 720p shows up, please use the GUI and change the resolution. Check if you can still switch back to 1080p.

  3. Also share /var/log/Xorg.0.log when you see 720p.

7

Hello,
Thanks a lot for reply.
Sorry for delay.
Please find the attached dmesg log when screen settle to1280x720 resolution.
Also in GUI shows maximum resolution of 1280x720 only.
Also find the attached Xorg log.
Please guide me on this.
displaychk.txt (77.9 KB)

DisplaySettings
DisplaySettings1920×1080 150 KB

Xorg.0.log (17.2 KB)

8

Hello WayneWWW,
Hope you are good.
Any clue on this topic?
Actually one thing I want to mention here that as Jetson SOM when boots up in our custom carrier board initially its in 1920x1080 resolution, after finishing all initialisation it negotiate to 1280x720 resolution.
On the other part when same SOM we put in devkit it permenantely gives 1920 x1080 resolution.
When I was searching on that I found below link
https://docs.nvidia.com/jetson/archives/l4t-archived/l4t-3243/index.html#page/Tegra%2520Linux%2520Driver%2520Package%2520Development%2520Guide%2Fjetson_eeprom_layout.html
Its a layout of Jetson EEPROM.
Here I am slightly confuse about whether this EEPROM is one who is on devkit carrier board or its on module ?
If you check this layout there Byte number 16 is assigned for Display Configuration.
Is there any display setting saved on EEPROM and after booting SOM takes that setting and configure display?
In our custom carrier board we dont have EEPROM.
Please guide me on this topic

9

Hi,

Sorry for late reply. Actually, I already knew what might be the reason for this issue when you said you saw 720p…

It is not related to eeprom.

This looks like your custom board issue. Your custom board is not able to read the EDID from your monitor. Under such situation, our driver has a hard-coded edid string which will tell the driver to output 720p.

Below log from what you shared a a proof…

[  124.511874] tegra-i2c 3190000.i2c: I2C_INT_STATUS - 0x2
[  124.511979] tegra-i2c 3190000.i2c: i2c transfer timed out addr: 0x50
[  124.512665] tegradc 15200000.nvdisplay: hdmi: edid read failed
[  124.512865] tegradc 15200000.nvdisplay: hdmi: using fallback edid
[  124.512976] tegradc 15200000.nvdisplay: blank - powerdown
[  124.573722] extcon-disp-state external-connection:disp-state:

When you see dmesg spew lots of i2c timeout error, it indicates the chance of edid read failure.

10

Hello WayneWWW,
Thanks a lot for reply.
Yes I tried to compare DMSEG log from both Nvidia board and custom board.
In custom board we are not able to EDID data.
Is it because of inproper layout design?
DMESG COMPARISON.txt (1.2 KB)

11

Yes, possibly because of hardware design problem.

13

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