Uses for SPI Flash

[danielt]

You can have image that has uboot behaving this way: preferring SD over eMMC.

Booting from the spi flash with SD over eMMC preference still does have an advantage: it makes it possible to wipe-out or re-partition the eMMC, and even if something is messed up it will be still able to recover without the need of a screwdriver.
There is a catch, though - if you mess up u-boot in the SPI flash then you will be in trouble. I think that on RockPro the boot priority is selectable using a jumper. So I wonder - what's the boot priority on PBP and is it also jumper selectable?

I saw the following in the RockPro docs to forcefully avoid SPI boot (e.g. prevent the SPI device from observing the clock by shorting it out on the 40 pin header):
https://wiki.pine64.org/index.php/ROCKPr...booting.29

I haven't seen the production schematics for PBP but there is no 40 pin header and the pre-production drawings didn't offer any comfortable equivalent. You apply the same short directly to the pins of  the flash chip... but I doubt I'm coordinated enough to pull it off reliably. In the end I ended up ordering a CH341A and a test clip since that should be able to get me out of almost anything ;-) .