From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: "Russell King - ARM Linux" <linux@arm.linux.org.uk>
Cc: David Xiao <dxiao@broadcom.com>, Ben Dooks <ben-linux@fluff.org>,
Hugh Dickins <hugh.dickins@tiscali.co.uk>,
Robin Holt <holt@sgi.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"v4l2_linux" <linux-media@vger.kernel.org>,
"linux-arm-kernel@lists.arm.linux.org.uk"
<linux-arm-kernel@lists.arm.linux.org.uk>
Subject: Re: How to efficiently handle DMA and cache on ARMv7 ? (was "Is get_user_pages() enough to prevent pages from being swapped out ?")
Date: Fri, 7 Aug 2009 09:48:24 +0200 [thread overview]
Message-ID: <200908070948.26389.laurent.pinchart@ideasonboard.com> (raw)
In-Reply-To: <20090806222543.GG31579@n2100.arm.linux.org.uk>
On Friday 07 August 2009 00:25:43 Russell King - ARM Linux wrote:
>
> As far as userspace DMA coherency, the only way you could do it with
> current kernel APIs is by using get_user_pages(), creating a scatterlist
> from those, and then passing it to dma_map_sg(). While the device has
> ownership of the SG, userspace must _not_ touch the buffer until after
> DMA has completed.
If the buffers are going to be reused again and again, would it be possible to
mark the pages returned by get_user_pages() as non-cacheable instead ?
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2009-08-07 7:46 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-06 10:08 Laurent Pinchart
2009-08-06 11:46 ` Ben Dooks
2009-08-06 13:06 ` Laurent Pinchart
2009-08-06 18:46 ` David Xiao
2009-08-06 19:16 ` Chetan.Loke
2009-08-06 20:15 ` Jamie Lokier
2009-08-06 22:25 ` Russell King - ARM Linux
2009-08-07 5:59 ` David Xiao
2009-08-07 7:58 ` Laurent Pinchart
2009-08-07 8:10 ` Russell King - ARM Linux
2009-08-07 9:54 ` Jamie Lokier
2009-08-07 9:59 ` Russell King - ARM Linux
2009-08-07 12:07 ` Laurent Desnogues
2009-08-07 13:15 ` Robin Holt
2009-08-07 19:01 ` Russell King - ARM Linux
2009-08-07 20:11 ` Laurent Pinchart
2009-08-07 20:28 ` Russell King - ARM Linux
2009-08-07 22:25 ` David Xiao
2009-08-10 13:49 ` Laurent Pinchart
2009-08-07 8:08 ` Russell King - ARM Linux
2009-08-07 10:23 ` Jamie Lokier
2009-08-07 19:03 ` Russell King - ARM Linux
2009-08-11 9:31 ` Catalin Marinas
2009-08-11 18:23 ` David Xiao
2009-08-07 7:48 ` Laurent Pinchart [this message]
2009-08-25 12:53 ` Steven Walter
2009-08-25 22:02 ` David Xiao
2009-08-25 23:17 ` Laurent Pinchart
2009-08-26 17:22 ` David Xiao
2009-09-01 13:31 ` Russell King - ARM Linux
2009-09-01 18:08 ` David Xiao
2009-09-01 13:28 ` Russell King - ARM Linux
2009-09-01 13:43 ` Laurent Pinchart
2009-09-01 14:18 ` Russell King - ARM Linux
2009-09-01 16:53 ` Hugh Dickins
2009-09-02 15:10 ` Imre Deak
2009-09-03 7:31 ` Imre Deak
2009-09-03 8:36 ` Russell King - ARM Linux
2009-09-08 13:05 ` Steven Walter
2009-08-07 7:29 ` Laurent Pinchart
2009-08-07 8:12 ` Matthieu CASTET
2009-08-07 10:13 ` How to efficiently handle DMA and cache on ARMv7 ? (was " Is " Laurent Pinchart
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