Hi guys,
Here's a proposal how to avoid changing the host boot software for the SPL case:
- Power on - Boot ROM announces usb device (0x15a2:0x0054 or 0x15a2:0x0054 or 0x15a2:0x0063) - Host software uploads SPL over OTG - Board initializes DDR - Board initializes USB-OTG and announces again as a usb device with slightly different PID (0x15a2:0x0055 or 0x15a2:0x0056 or 0x15a2:0x0064) or a special PID (0x15a2:0xffff), thus needs to implement FSL boot protocol - Both imx-usb-loader and mfgtool already have easy mechanism to detect boards' by vid-pid and to sequence actions based on it. So basically we'll just need an additional config for the host boot programs, which need to feed the 2nd boot stage (one more file for imx-usb-loader, and one more config section for the mfgtool), but otherwise it will be quite straight-forward.
Overall, from the PC host this boot sequence will look like 2 boot sequences for 2 separate usb devices (1 for SPL, 1 for u-boot.img).
Probably the most important question is "how easy is to implement the FSL boot protocol in the remaining OCRAM free space". What do you think?
Regards, Nikolay