Recovery Mode is not detected

Products Support HiKey 960
#1

Hello !

I tried to modify the bootloader image using fastboot. However, after reboot the board displays
“Cannot load BL2” and the booting stops.

So I wanted to change the bootloader back to default by going into recovery mode (Switch 1-2 ON and 3 OFF) however, the board is not recognized by my host computer and thus I cannot follow the next steps of this link

I have the following questions:
Is it possible that I broke the board even if it is a dev board ?
Where is the boot sequence stored for recovery?
Is there any way to boot from SD card / USB?

Thanks :slight_smile:

#2

The boot sequence for recovery is held in ROM on the SoC itself. If its not working its always a good idea to unhook everything from the board except USB type C connector and the power (it is true only some of the connectors matter for recovery but the above guidance has the benefit of absolute clarity).

Having done all that, it would be good to know what, if anything, you are seeing in the dmesg buffer of your workstation when you power up the Hikey960.

#3

Thanks for you reply.

I connected only the USB-C and Power but nothing is happening. dmesg does not show anything.
If I plug another fresh Hikey960 in recovery mode it is correctly detected.

Probably I somehow modified the boot sequence for recovery.
I saw that there is some JTAG connector so I will try to use it for debug.

#4

As far as I know it should be pretty hard to damage the recovery sequence… as I said, I think it is in ROM and runs from SRAM. On most systems it is just a little bit of stub code that allows you to download some code to program DDR and adopt a better USB protocol.

So, for me it sounds really odd that the board is alive enough to complain that is can’t load BL2 but too broken to run a recovery sequence. In addition to JTAG (which is a bit of a long shot IMHO) you might also see if there are any clues on the debug UART (if your board has one). It is marked #12 in the Hikey960 hardware manual and I think this is where messages from the boot ROM emerge (I’m afraid I can’t test it… I have a pre-production board and don’t have this connector).

#5

Unfortunately, I also don’t have the debug UART :slight_smile:
So I will go for JTAG!

Thanks for your answers.