This patch disables display driver in u-boot which improves EDID detection
https://forum.armbian.com/topic/13651-pine-a64-no-hdmi-signal/?do=findComment&comment=99169

diff --git a/configs/nanopi_m1_plus2_defconfig b/configs/nanopi_m1_plus2_defconfig
index ea271871..99687477 100644
--- a/configs/nanopi_m1_plus2_defconfig
+++ b/configs/nanopi_m1_plus2_defconfig
@@ -20,3 +20,4 @@ CONFIG_SPL_SPI_SUNXI=y
 CONFIG_SUN8I_EMAC=y
 CONFIG_USB_EHCI_HCD=y
 CONFIG_SYS_USB_EVENT_POLL_VIA_INT_QUEUE=y
+CONFIG_VIDEO_DE2=n