RE: [PATCH v2 1/3] Revert "mtd: spi-nor: remove Fujitsu MB85RS1MT support"

[Ronan Dalton]

Hi Takahiro,

> We don't add any FRAM chips in SPI-NOR...

The SPI-NOR subsystem has support for the cy15x104q chips, which are
FRAM chips. There is also support for Everspin MRAM chips, which are
comparible to FRAM (and are also of small size).

Because of this, we thought there was precident to add support for this
chip. I was under the impression that the opcodes used to interact with
the chip had a greater significance than the underlying technology used,
and this chip fits in with the other spi-nor chips based on that. Feel
free to correct me if I'm wrong here.

> > The use is for a small amount of additional storage separate to the main
> > system NAND flash for some small "critical" files that we don't want to
> > lose. We've been using devices like the mchp23lcv1024 and mr25h40 on
> > other products for some time.
> > 
> For that use, how about using tmpfs with NVMEM backup?

Could you elaborate on this? I'm familiar with tmpfs but not with using
NVMEM as a backup for it. Is there some method of syncing a tmpfs to
NVMEM that the kernel provides?

Thanks,
Ronan.