4K?

[longsleep]

Code:

[   12.619258] [HDMI WRN] file:drivers/video/sunxi/disp2/hdmi/drv_hdmi.c,line:331:    unsupported video mode 30 when set display mode

caused by 'optargs=disp.screen0_output_mode=2160p24' in uEnv.txt. But my display is only capable of 2560x1600.

For whatever reason the A64 HDMI driver does not have 2160p24 implemented. Only 2160p30 and 2160p25 - so try one of those. For reference see https://github.com/longsleep/linux-pine6...#L268-L286 - only those in that table can be used for HDMI with Pine64.