[PATCH V2] mtd: spi-nor: add Kconfig option to disable 4K sectors

[Brian Norris]

On Sun, Aug 17, 2014 at 11:27:26AM +0200, Rafał Miłecki wrote:
> Current situation with 4K sectors is quite messy. First of all, some
> MTD "users" don't work with such small size. An example may be UBIFS
> which requires 15 KiB erase blocks as a minimum. In theory spi-nor
> should provide multiple erase regions and MTD "users" should use the
> one they need. Unforunately that is not implemented.
> 
> In the result our flashes database in spi-nor is hackish. For some
> flashes we pretend they don't support 4K sectors just because some
> distribution uses UBIFS on it. This ofc leads to conflicts, like
> Samsung using w25q128 with 4K sectors vs. OpenWrt requiring it to
> pretend it's 64 KiB blocks only.
> 
> My idea (plan?) for fixing this situation:
> 1) Use real hw info (this requires a way for disabling 4K for now)
> 2) Provide detailed info about erase regions
> 3) Make UBIFS work with devices that support 4K sectors
> 
> Signed-off-by: Rafał Miłecki <zajec5 at gmail.com>
> ---
> V2: Add extra info about performance in Kconfig. Thanks Kevin.
>     Fix typo s/users/uses/ in commit message.

Pushed to l2-mtd.git. Thanks!

Now we should probably try to handle (1), at least, so that the data
table holds fully accurate info about the flash.

Brian