[U-Boot] mtd/cfi: SST39VF3201B flash model not properly handled

[Angelo Dureghello]

Dear All,

as Wolfgang Denx suggested me, i am trying to use the u-boot CFI driver with 
a CFI flash (SSTVF3201B).

This flash chip allows erasing/writing blocks of 4 KBytes (called "sectors" 
in the SST datasheet), or 64 KBytes (called "blocks"). 

The command sequence table for this flash shows 2 different commands to 
operate on these 2 kind of blocks. 0x50 is for "sector erase" and "0x30" (the
command used from u-boot CFI driver as AMD_CMD_ERASE_SECTOR) is for the
64KB "block" erase.

The issue:
now, u-boot CFI driver works fine on 64KB boundary ranges, but if i expect
to erase a 4KB sector size i get a full 64KB block erased. 

Proposed solution:
Initially, a single sector size definition would be good enough for this chip, 
so the user should specify if he wants a 64 or 4 KB sector to be used, using
some CFG_X.
CFI driver, through queries, should be able to identify this particular chip
so that it can be handled in a specific way from the CFI driver (cmd 0x50 for
4KB secotrs, or 0x30 for 64KB secotrs).

I am thinking about to post a patch on this.
Anyway, until new AMCORE board patch is not accepted, there is the chance 
this can result as a "dead code" if no-one use this flash chip except me.
 
So, before i start, please let me know how to proceed, maybe is better to use
a specific flash.c for my board for now ? 
Or if you think a patch can be useful, any suggestion on how to implement it 
is really welcome.


Best Regards,
Angelo Dureghello