I connect 7" hdmi display from waveshare to orange pi one on mainline dev kernel.
When it is powered before orange, it works ok.
But it don't work if it is powered at the same time.
I am tried to add hpd_delay at the top of boot.cmd:
setenv video-mode sunxi:1024x768-24@60,monitor=hdmi,hpd=1,hpd_delay=20000,edid=1
the do mkimage -C none -A arm -T script -d