[OPI PC+] u-boot : starting USB... don't start automatically

Hello,

[OPI PC+] u-boot : starting USB... don't start automatically

what i did:
- got 'Armbian_5.35_Orangepipcplus_Ubuntu_xenial_default_3.4.113.img'
- extracted 'u-boot-sunxi-with-spl.bin' from above .img and put it on some USB key
- booted from SD card with  Armbian 5.35 (above)
- wrote 'OpenELEC-H3.arm-7.0-devel-20161026221641-r23113-g64b34b3-opipcplus.img' on eMMC:
dd if=/mnt/usb/OpenELEC-H3.arm-7.0-devel-20161026221641-r23113-g64b34b3-opipcplus.img of=/dev/mmcblk1 conv=notrunc,noerror bs=4k
 (boot okay without SD)
- and finaly, wrote u-boot & SPL onto the eMMC:
dd if=u-boot-sunxi-with-spl.bin of=/dev/mmcblk1 bs=1024 seek=8 && sync

my issue under u-boot:

when i boot from SD card, USB scanning works well:

U-Boot SPL 2017.09-armbian (Nov 22 2017 - 16:49:59)
DRAM: 1024 MiB
Trying to boot from MMC1

U-Boot 2017.09-armbian (Nov 22 2017 - 16:49:59 +0100) Allwinner Technology

CPU:   Allwinner H3 (SUN8I 1680)
Model: Xunlong Orange Pi PC Plus
DRAM:  1 GiB
MMC:   SUNXI SD/MMC: 0, SUNXI SD/MMC: 1
In:    serial
Out:   vidconsole
Err:   vidconsole
Net:   phy interface0
eth0: ethernet@1c30000
230454 bytes read in 187 ms (1.2 MiB/s)                      <- boot.bmp i guess
starting USB...
USB0:   USB EHCI 1.00
USB1:   USB OHCI 1.0
USB2:   USB EHCI 1.00
USB3:   USB OHCI 1.0
USB4:   USB EHCI 1.00
USB5:   USB OHCI 1.0
scanning bus 0 for devices... 1 USB Device(s) found
scanning bus 2 for devices... 2 USB Device(s) found
scanning bus 4 for devices... 1 USB Device(s) found
scanning bus 1 for devices... 2 USB Device(s) found
scanning bus 3 for devices... 1 USB Device(s) found
scanning bus 5 for devices... 2 USB Device(s) found
       scanning usb for storage devices... 1 Storage Device(s) found
Autoboot in 1 seconds, press <Space> to stop

=>

but not when i boot from the internal eMMC:

=> reset
resetting ...

U-Boot SPL 2017.09-armbian (Nov 22 2017 - 16:49:59)
DRAM: 1024 MiB
Trying to boot from MMC2

U-Boot 2017.09-armbian (Nov 22 2017 - 16:49:59 +0100) Allwinner Technology

CPU:   Allwinner H3 (SUN8I 1680)
Model: Xunlong Orange Pi PC Plus
DRAM:  1 GiB
MMC:   SUNXI SD/MMC: 1, SUNXI SD/MMC: 0
In:    serial
Out:   vidconsole
Err:   vidconsole
Net:   phy interface0
eth0: ethernet@1c30000
Autoboot in 5 seconds, press <Space> to stop
=>

Nevertheless, usb start works manually but i can't stop boot with usb keyboard attached on USB...

Thanks for help or some ideas
Philippe