On Tue, 2009-10-27 at 16:52 -0600, Jonathan Haws wrote:

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Jonathan Haws wrote:

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I had thought about using MTD, but decided against it because

with

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previous benchmarking that we did with MTD and our custom

driver,

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we

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found that our custom driver was about 10x faster.

Ouch.  Any idea where the slowdown is coming from?

From what I remember (I would have to dig up notes to make sure)

it is something to do with MTD looking for a signal to go high that
is processed a bunch before MTD even sees it.  Our flash produces a
hardware ready signal that we are triggering off of to move on.  MTD
took much longer to report to us that the hardware was ready.

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Thanks

=20
It would be interesting to know in more detail what is was. If we
have a
10x performance increase hiding from for us I would be very
interested
in knowing where it is.
=20
Are you using some custom command to the flash that the generic chip
drivers in Linux is not yet supporting ?

Looking through our notes and talking with the engineer who was performing =
the tests, it was exactly that - MTD was waiting for a signal that was prod=
uced differently than the hardware ready signal.  By simply polling the fla=
sh until the hardware ready signal toggled we were able to get a much faste=
r read and write speed.  Granted, most of our signals are being sent throug=
h a CPLD, so that may be why MTD did not work as well.