Thanks for your share. The usb dl need the SD/TF card to boot to u-boot? When I boot the duo without SD/TF Card, the board will be loop in USBI → reset. Like that:
WD.C.SCS/0/0.WD.URPL.USBI.USBW/1000.USBL.BS/EMMC.PS. E:load param1 (-78)
PS. E:load param1 (-78)
PS. E:load param1 (-78)
PS. E:load param1 (-78)
PS. E:load param1 (-78)
PS. E:load param1 (-78)
PS. E:load param1 (-78)
PS. E:load param1 (-78)
E:Boot failed (8).
E:ra=0x440a264
E:RESET:panic:-1