eMMC stuck in 4k sector mode

[dangowrt]

I wanted to try if using 4k sectore size instead of 512B emulated sectors makes any difference in terms of performance on my 008GB0 eMMC disk, so I set USE_NATIVE_SECTOR in EXT_CSD to 1.
The performance difference turned out to be negligible, but 4k sectors are problematic e.g. because they are not supported by U-Boot loader.
Hence I would like to return to use emulated 512B sectors (the factory state of the disk).
However, writing 0 to USE_NATIVE_SECTOR[62] register has no effect.
As newer versions of the eMMC specification are not (yet) public, I'd like to know if this register happens to be write-once -- if so, we should document that in mmc-utils to prevent other people doing stupid mistakes like me now...

Anyone?

[DRUG]

Hi!
How are you interfacing to read and write from this device?

AFAIK this is a BGA 153 right?

[dangowrt]

Yes, this is a BGA chip and it's soldered onto a devboard (Bananapi R3) I've been given access to.
I can play with the eMMC because the board can also boot from SPI-NAND or SPI-NOR, hence not exclusively relying on eMMC for booting.
I don't fancy removing it from the board, but if that's the only way to reset that setting, well, I'll go to a nearby phone repair shop and have them do that.