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List:       uclinux-dev
Subject:    RE: [uClinux-dev] PATCH: speedup of flash writing (cfi_cmdset_0002.c)
From:       "Falk Brettschneider" <falk.brettschneider () gmx ! de>
Date:       2006-04-27 7:45:56
Message-ID: 647.1146123956 () www021 ! gmx ! net
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Hi,

> --- Ursprüngliche Nachricht ---
> Von: "Barry Baldwin" <bbaldwin@indyme.com>
>
> Just out of curiosity, what flash chip are you using?  Our
> flash write times are painfully slow and we might want to design in a
> different flash chip if we can speed up our write times.
I have an AMD flash of 16MB (Am29LV128) which is accepted by the CFI
auto-detection. Look at
http://www.amd.com.cn/CHCN/assets/content_type/white_papers_and_tech_docs/25270c5.pdf
in table 11 for the "Write to Buffer" command.
I think all bigger flash chips have that CFI command AA 55 25 count.
Having file access via JFFS2 system (including compression of the data with
zlib) the write time of my firmware file (350kB) is about 6secs with my
patch, I just use fopen, fwrite, fflush, fclose for that. In case of direct
writing&verifying (means not using JFFS2) I can write a 900kB Linux kernel
in 7 seconds.

BTW: I don't have a clue who maintains the flash drivers for uclinux and how
there is a chance to get my patch in the public CVS. Can anybody help,
please?

Cheers, F@lk

> 
> Thanks very much,
> Barry
> 
> > -----Original Message-----
> > [mailto:uclinux-dev-bounces@uclinux.org]On Behalf Of Falk Brettschneider
> > 
> > I patched drivers/mtd/chips/cfi_cmdset_0002.c with the result that
writing
> > to my flash is significantly faster now (10 times or more). I don't use
> > bypass mode, but switch to fast programming mode. In that mode I can
write
> > 32 dwords at once instead of the usual 16bit access.
> > It works perfectly here, but look at the patch, it needs some changes to
> > generalise it. E.g. I hard-wired my flash base address.
> > I want to give my patch to you as pattern for a better fix for speedup
of
> > that driver family. I'm also not sure if that fast-programming mode (AA
55
> > 25 count) is available for all CFI chips in general.
> > Any feedback would be welcome.
> > Cheers, F@lk
> > 

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