[U-Boot-Users] [PATCH RFC] ARM: Davinci: NAND fix for large page ECC and linux compatibility

[Troy Kisky <troy.kisky@boundarydevices.com>]

>>> +#define CFG_LINUX_COMPATIBLE_ECC
>>> + */
>> It seems odd that backwards compatibility requires turning *off* an  
>> option with "compatible" in the name...  I'd invert the sense of the  
>> ifdef, and have it be something like CFG_BROKEN_ECC_COMPATIBILITY.
> 
> The concern with this is people that use their own custom config
> files will need to add this #define when they upgrade. How about
> just changing the name to CFG_NEW_NAND_ECC_FORMAT then?

I like CFG_NEW_NAND_ECC_FORMAT better as well.

> #if defined(CFG_NAND_LARGEPAGE) && !defined(CFG_LINUX_COMPATIBLE_ECC)
> /* Comment this #error out only if you really really have to. */
> #error "You are using old ECC code that is broken on large page devices. See doc/README.davinci"
> #endif
> 
> This forces the user to make a choice - they'll probably curse while
> they're doing it, but they can't plead ignorance when they find
> their large page NAND isn't detecting ECC errors.
> 
I like this too. Maybe a #warning for small pages as well. Of course
both would also depend on #ifdef CFG_NAND_HW_ECC.


>> Perhaps we could use some currently unused OOB byte as a marker
>> for new/old ECC layout?
> 
> Could do, but any filesystems which use the OOB bytes might step on
> these. It also complicates the code even moreso and creates a lot
> more scenarios to test and that could go wrong.
> 
> I really do believe it should be a clean switch from one format to
> the other, for both small and large page NAND, with no run-time
> backwards compatibility. But that's just my POV.

I hope that eventually we can remove the old format, but this patch
has my ack.

Thanks Bernard

Troy