[U-Boot] PATCH: bugfix for nand erase failure with bad blocks

[Wolfgang Denk]

Dear Scott,

In message <4A37FE47.3030203 at freescale.com> you wrote:
>
> > I see - thanks for the explanation.
> > 
> > Hm... actually I think the write should fail in such a case...
> > 
> > Scott, what do you think?
> 
> I think the current behavior is reasonable.  You're erasing a specific 
> region of flash, not an amount needed to hold a certain amount of data.
> 
> While I can see the appeal of Michele's suggestion, I think it would be 
> more error-prone as people trying to erase a region rather than just the 
> size of data could erase too much.

That was my initial thought, too, which is why I asked Michele for an
explanation.

when I think about typiical use cases like automatic uypdate script
similar to:

	=> tftp 200000 filename
	=> nand erase 0 +${filesize}
	=> nand write 200000 0 ${filesize}

I (and probably any other user) will  expect  that  the  "erase"  and
"nand  write"  commands  use  the  same  interpretation  for the size
argument, i. e. that and "erase" followed by a "write" will have made
sufficient room to write all data.

Thus I reconsidered and think the patch is actually reasonable, as it
does what is the most practical use case needs.

> It definitely should not be an error to erase a region that happens to 
> contain a bad block.  Bad blocks are expected and we need to work around 
> them.

Agreed.

But it should be an error when writing to not erase flash blocks.

Best regards,

Wolfgang Denk

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