[PATCH] mtd: support for bit-reversed CFI cmd/query
Nikita V. Youshchenko
yoush at cs.msu.su
Tue Apr 22 15:08:32 EDT 2008
> On Wed, 2008-02-27 at 23:48 +0300, Nikita V. Youshchenko wrote:
> > mtd: support for bit-reversed CFI cmd/query
> >
> > Some embedded boards have flash chips connected with reversed bit
> > order. Example for 16-bit width:
> > chip D0 is bus D15
> > chip D1 is bus D14
> > ...
> > chip D15 is bus D0
> > It works perfectly for data access, however probing and issuing
> > CFI commands for such chips require bit reversing. This patch adds
> > support for this.
> >
> > Signed-off-by: Nikita Youshchenko <yoush at cs.msu.su>
>
> Am I missing something, or did you only reverse the bits on 16-bit and
> 64-bit access, and not 8-bit or 32-bit?
Hmm... Looks so :(.
The board I work with has 16-bit flash, so I could not test others.
Btw, the vendor of the board confirmed that such a strange flash chip
connection is 'an old hardware bug', however they decided to keep it in
current and future revisions of the board 'for backward compatibility'.
Is it a good idea to support such strange cases in the official kernel?
If yes, I may send an updated patch.
Nikita
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