HDMI to DSI Driver won't work. Need help to troubleshoot.

Jiten Chandiramani · August 22, 2017

Hi Guys,

I bought one of these pcDuino 4 (Nano Pi M1) boards: http://www.linksprite.com/pcduino4-nano/

Works great with Armbian Legacy Kernal.

I got this screen with the HDMI + DSI Driver Board. Works fine with normal PC -> HDMI output but will not work with the Nano Pi..
https://www.alibaba.com/product-detail/LS055R1SX04-1440x2560-5-5-2K-LCD_60672828148.html?spm=a2700.7724838.2017115.1.3c93b095HGc0XS

The LCD screen just turns on then off and on and off forever. It never locks on to the HDMI signal. The Nano Pi M1 works just fine with a regular monitor but not with the LCD/Driver combo. I have seen some purple images come up on the screen and sometimes I can see 4 desktops on the tiny screen just for a split second. I have also tried multiple resolutions using the h3disp command. Not sure how to debug this issue. I have tried using multiple power sources, different HDMI cables, with no luck.

Any help would be awesome. I am new to Linux so I am just not sure how to figure out what the issue is.

Thanks You

Jay

jernej · August 22, 2017

there are 3 possible reasons or mix of them:

- resolution issue - legacy kernel supports only standard resolutions like 1280x720 or 1920x1080. Description of your adapter sadly doesn't say if it supports autoscaling or it supports only native resolution of the panel. Let's hope it is first.

- HDMI/DVI mode - since your screen doesn't seem to support sound, it would probably be better to switch to DVI mode (-d switch for h3disp).

- colors - "-c" switch with h3disp

Did you try to use "-d" and "-c" switches when you played with h3disp? If not, try with -d first and then with -c.

Jiten Chandiramani · August 22, 2017

Yes I tried both -d and -c "full scale color".. Did not fix the issue.

Is there a way to check the HDMI EDID to see what the adapter supports?

Also I have hooked the LCD screen up to my Windows PC as a second monitor and adjust the screen resolution up and down and it seems to work just fine.

zador.blood.stained · August 22, 2017

Just now, Jiten Chandiramani said:

Is there a way to check the HDMI to see what the adapter supports?

You can dump the EDID data from your adapter. Exact instructions will depend on your OS and hardware (graphics card). For Windows I believe there are simple programs (Like DumpEDID and MonitorInfoView) that can do this.

Jiten Chandiramani · August 22, 2017

Ok I can try that and see what it says. Is there a way to check it on the Nano Pi M?

I wanted to make sure the adapter is being detected by the OS. My bootup screen does not show me anything about whats happening with the HDMI. I just see "vcc-hdmi-18".

Jiten Chandiramani · August 24, 2017

So I hooked it up to my windows machine and did an EDID dump and here is what I got:

DumpEDID v1.06

Copyright (c) 2006 - 2017 Nir Sofer

Web site: http://www.nirsoft.net


*****************************************************************

Active                   : Yes

Registry Key             : DISPLAY\LZT0001\5&abb2a63&0&UID4352

Monitor Name             : LS060R1SX01  

Serial Number            : 00000000     

Manufacture Week         : 12 / 2017

ManufacturerID           : 21555 (0x5433)

ProductID                : 1 (0x0001)

Serial Number (Numeric)  : 0 (0x00000000)

EDID Version             : 1.3

Display Gamma            : 2.20

Vertical Frequency       : 23 - 75 Hz

Horizontal Frequency     : 15 - 240 KHz

Maximum Resolution       : 1440 X 2560

Support Standby Mode     : No

Support Suspend Mode     : No

Support Low-Power Mode   : No

Support Default GTF      : No

Digital                  : Yes



Supported Display Modes  :

     248 X  155  60 Hz

    1440 X 2560  60 Hz



*****************************************************************

Looks like the driver only supports these two Resolutions and when I do h3disp I get the following supported resolutions

I guess this means the driver does not support scaling? Any advice on how I can add support for this screen?