Re: ubi: refuse attaching mtd3 - MLC NAND is not supported

[Richard Weinberger <richard@nod.at>]

Mathieu,

Am Freitag, 25. Mai 2018, 12:12:02 CEST schrieb Mathieu Malaterre:
> > No. MLC is simply not supported and not safe to use.
> > With that commit we reflect the state of the code and stop giving wrong promises.
> 
> ACK. Would you recommend an alternate filesystem then ?

There is none.

One option you have is putting the MLC NAND into SLC mode, some support this.
This needs to be achieved by a vendor specific command which is often undocumented.

Boris and I experimented also with software SLC mode in UBI.
If you want you can revive our work.
 
> > I can hardly believe that it has been working great so far, did you
> > ever do power-cut tests?
> > Or are there other mechanisms on your board that make MLC usable by UBI?
> > For example SLC-emulation.
> 
> Looking quickly at the tech specs:
> 
> https://www.elinux.org/CI20_Hardware#ROM.2FNAND
> 
> ...
> Is provided by a single Samsung K9GBG08UOA NAND flash, using an 8bit
> data interface to the SoC.
> ...
> 
> So my understanding is that "it just worked" so far. I've tried
> contacting some of the people involved with the design of CI20 to get
> confirmation.

"just worked" in terms of nobody gave it a decent testing, I fear. ;-\

Thanks,
//richard