Modern SSDs would have some refresh logic of their own but I don't expect that in the cameras.
AFAIK, modern SSDs have error correction, which would flag corrupted bits before data loss. I don't know if they have any pro-active refresh, under normal use cases wear leveling would probably take care of it naturally.
In any case, I agree the cameras likely don't. Flash isn't archival storage, and a decade plus is well beyond the design life for consumer products like this. Unlike old film cameras, these things shouldn't be expected to be heirlooms that will work 50 or 100 years down the road. I suspect even Leicas and Hasselblads will bit rot about the same
So, I wondered what could we do about this? Wouldn't it make sense to have a functionality that iterates over the entire ROM area in a read a byte, write a byte, re-read the byte and if it's the same go on while otherwise write again kind of fashion? Just address by address so that even a power outage should ruin little?
Generally, flash is only written in larger blocks, and can only be written after an "erase". While the firmware function lets you write a single byte, under the hood what almost certainly happens is the whole block is read, the byte(s) are modified in memory, the block is erased, and then written. It's not immediately obvious to me how much of this happens in firmware code vs in the flash controller.
The flash in these cameras is presumably
NOR flash.
To further complicate things, on most of these cameras the functions to write to flash are also in flash. Refreshing the bit of firmware currently being executed could be sporty
The Canon firmware update process doesn't have this issue, because it uses a standalone executable which runs from RAM.
IMO, a more tractable approach would be to checksum the code and constant data areas in flash and compare them to a known good dump. This isn't trivial either, since there are regions used to store settings and calibration data. Of course, this doesn't give you proactive refresh, if a bit in the bootloader or startup code goes bad, you'd still be hosed, but statistically that should be a lot rarer.
