From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH] MTD: atmel_nand: optimize read/write buffer functions
Date: Wed, 29 Jun 2011 14:31:24 +0100 [thread overview]
Message-ID: <20110629133124.GO21898@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <4E0B2427.9020202@atmel.com>
On Wed, Jun 29, 2011 at 03:09:59PM +0200, Nicolas Ferre wrote:
> Le 28/06/2011 16:59, Russell King - ARM Linux :
> > I think you need to read Documentation/bus-virt-phys-mapping.txt,
> > particularly the part after "NOTE NOTE NOTE".
> >
> > Dereferencing ioremap'd memory is not permitted. That includes passing
> > it to memcpy. Even with a cast.
>
> So that means that I should use memcpy_fromio() even if the code if far
> less optimized.
>
> Shouldn't I re-implement some kind of IO copying function to deal with
> this IO memory so that I could take advantage of 8 words bursts?
You could improve the IO memcpy/set etc implementations, which are
currently mostly unloved - I think that's a catch-22 which really needs
solving. They're not efficient because no one has taken the time to use
them, and everyone's avoiding them because they're not very efficient.
So, as no one's using them no one's motivated to improve them.
next prev parent reply other threads:[~2011-06-29 13:31 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-28 11:50 [RFC PATCH] MTD: atmel_nand: optimize read/write buffer functions Nicolas Ferre
2011-06-28 11:10 ` Uwe Kleine-König
2011-06-28 13:58 ` Nicolas Ferre
2011-06-28 14:59 ` Russell King - ARM Linux
2011-06-29 13:09 ` Nicolas Ferre
2011-06-29 13:31 ` Russell King - ARM Linux [this message]
2011-07-04 13:02 ` Nicolas Ferre
2011-07-04 14:17 ` [PATCH V2] " Nicolas Ferre
2011-07-06 6:58 ` Artem Bityutskiy
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