How to use custom display with resolution 640x240

[bojidartonchev]

Hello,

I am having troubles getting a custom display 640x240 working with TinkerBoard2 (RK3399). Only noise is seen on the screen. In the screenshot you can see the full characteristics of the display. I am using yocto.

So far I have tried:

1. Created and installed a fb.modes file with the following content:

mode "640x240 60Hz 32bit (GTF)"
    # PCLK: 23.86 MHz, H: 29.82 kHz, V: 60.00 Hz
    geometry 640 240 640 240 32
    timings 41918 80 16 13 1 64 3
    hsync low
    vsync high
endmode

2. Setting the desired resolution in init.d script
   fbset -fb /dev/fb0 640x240

It had no effect...

In addition I can see the following lines in the UART Log:
can't find valid hdmi mode
and
[drm] [CRTC:70:crtc-1] state:1, vblank wait timed out

These does not appear when using a Full HD monitor.

Any help would be appreciated!

Best regards!

[bojidartonchev]

Turned out we have display controller issue and it is reporting wrong resolution 640x480. So I managed to workaround it with kernel cmdline parameter video=HDMI-A-1:640x480@60m,margin_top=0,margin_bottom=240