Possible QSPI issues in H7 chips

[victorallume]

I came across this post that details some intermittent issues in the QSPI peripheral of STM32H7 series MCUs. I'm not sure if micropython is affected, but putting it here in case anyone has any problems down the track
https://news.ycombinator.com/item?id=41073005

Be veeeery careful. STM32H QSPI peripheral is FULL OF very nasty bugs, especially the second version (supports writes) that you find in STM32H0B chips . You are currently avoiding them by having QSPI mapped as device memory, but the minute you attempt to use it with cache or run code from it, or (god help you) put your stack, heap, and/or vector table on a QSPI device, you are in for a world of poorly-debuggable 1:1,000,000 failures. STM knows but refuses to publicly acknowledge, even if they privately admit some other customers have "hit similar issues". Issues I've found, demonstrated to them, and wrote reliable replications of:

• non-4-byte-sized writes randomly lost about 1/million writes if QSPI is writeable and not cached

• non-4-byte-sized writes randomly rounded up in size to 2 or 4 bytes with garbage, overwriting nearby data about 1/million writes if QSPI is writeable and cached

• when PC, SP, and VTOR all point to QSPI memory, any interrupt has about a 1/million chance of reading garbage instead of the proper vector from the vector table if it interrupts a LDM/STM instruction targeting the QSPI memory and it is cached and misses the cache

Some of these have workarounds that I found (contact me). I am refusing to disclose them to STM until they acknowledge the bugs publicly.

[victorallume]

I got some more info on this, and it appears to be limited to using QSPI RAM, and only when in memory-mapped mode.