It turned out this "4-byte" ID might have been an honest mistake.
Regrettably, the chip Andreas has might be a counterfeit or is
damaged in some other way and shouldn't have ended up in a router.
Andreas reported his chip is returning just four bytes:
"98 f1 80 15 00 00 00 00".
However, according to Kioxia/Toshiba's datasheet, there should
have been at least another byte that would have contained the
correct OOB size that Andreas needed.
Miquel and Andreas are both favoring reverting the patch over
further, possibly hacky modifications:
"[Reverting] is the safest option here. Apart from this device, we
do not know how many devices have these damaged/counterfeit chips.
If it is just a couple and only on Fritzboxes, as suggested in the
Github issue the patch could be carried through OpenWrt[...]"
Thanks to several users on the openwrt forum and github issue,
who stayed along for the ride:
- Peter-vdL for reporting the issue and testing patches.
- neg2led and Hannu Nyman who did all the
datasheet digging and debugging.