From: catalin.marinas@arm.com (Catalin Marinas)
To: linux-arm-kernel@lists.infradead.org
Subject: memcpy alignment for DEVICE_nGnRnE
Date: Fri, 21 Feb 2014 10:53:08 +0000 [thread overview]
Message-ID: <20140221105307.GE25363@localhost> (raw)
In-Reply-To: <53072343.4080505@marvell.com>
Hi Zhou,
On Fri, Feb 21, 2014 at 09:58:27AM +0000, Zhou Zhu wrote:
> We faced one issue using memcpy for memory type DEVICE_nGnRnE
> (pgprot_noncached). If the address is not aligned, exception would
> happen due to the alignment of this type could not be handled by hardware.
Indeed, that's expected. This memory type is the equivalent of Strongly
Ordered.
> Is there any plan and ongoing patch to support this or we need to keep
> address aligned for memcpy using pgprot_noncached memory in drivers?
You either change the memory type to pgprot_writecombine() or use the
right API (memcpy_toio/memcpy_fromio, these could be further optimised,
similar to powerpc for example, but I didn't get there yet).
--
Catalin
next parent reply other threads:[~2014-02-21 10:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <53072343.4080505@marvell.com>
2014-02-21 10:53 ` Catalin Marinas [this message]
2014-04-08 0:35 ` memcpy alignment for DEVICE_nGnRnE Michael Bohan
2014-04-08 0:35 ` Michael Bohan
2014-04-08 11:49 ` Catalin Marinas
2014-04-08 11:49 ` Catalin Marinas
2014-04-08 23:39 ` Michael Bohan
2014-04-08 23:39 ` Michael Bohan
2014-04-09 8:17 ` Catalin Marinas
2014-04-09 8:17 ` Catalin Marinas
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