Hi @HieuNong
On my toradex board (imx8) I successfully able to set customise resolution using this command from u-boot command
setenv vidargs video=HDMI-A-1:1280x800@60e
And after that it will set on cmdline and showing on /modes
cat /proc/cmdline
root=PARTUUID=94874b25-02 ro rootwait console=tty1 console=ttymxc2,115200 consoleblank=0 earlycon video=HDMI-A-1:1280x800@60e
cat /sys/class/drm/card1-HDMI-A-1/modes
1280x800
1280x720
1280x720
1280x720
800x600
720x576
640x480
640x480
720x400
Also it is “1280x800” reflected on display. but in another board I am not able to set. that board is congatec imx8 when i set vidargs it will shoeing on /cmdline but not showing in /sys/class/drm/card1-HDMI-A-1/modes
Can you help me from which place I should start to debug ? I check /driver/gpu/drm/ files there is no any important changes and in edid.c file.