From: "Dan Williams" <dan.j.williams@intel.com>
To: "Guennadi Liakhovetski" <g.liakhovetski@gmx.de>
Cc: linux-kernel@vger.kernel.org,
linux-fbdev-devel@lists.sourceforge.net, adaplas@gmail.com,
"Sascha Hauer" <s.hauer@pengutronix.de>,
linux-arm-kernel@lists.arm.linux.org.uk
Subject: Re: [PATCH 1/4 v2] dmaengine: add a tx_free method to struct dma_async_tx_descriptor
Date: Wed, 10 Dec 2008 12:58:09 -0700 [thread overview]
Message-ID: <e9c3a7c20812101158h3de9c604i1c88bb7c412ccf02@mail.gmail.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0812101129340.4578@axis700.grange>
On Wed, Dec 10, 2008 at 3:36 AM, Guennadi Liakhovetski
<g.liakhovetski@gmx.de> wrote:
> From: Guennadi Liakhovetski <lg@denx.de>
>
> Some users reuse DMA transaction descriptors multiple times and need an
> explicit call to release them. An example of such a user is Video4Linux, which
> has to be able to release descriptors on ioctl(VIDIOC_DQBUF).
>
> Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
Hi Guennadi,
Other dmaengine drivers have tasklets that scan the list of completed
descriptors and free the "acked" ones. This happens in the cleanup
tasklet...
/me looks
...hmm this driver does not have a cleanup routine? Ideally support
for ioctl(VIDIOC_DQBUF) could be achieved through this mechanism
without needing to increase the size of dma_async_tx_descriptor (which
has cache utilization impacts on other drivers).
--
Dan
next prev parent reply other threads:[~2008-12-10 19:58 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-10 10:35 [PATCH 0/4 v2] i.MX31: dmaengine and framebuffer drivers Guennadi Liakhovetski
2008-12-10 10:36 ` [PATCH 1/4 v2] dmaengine: add a tx_free method to struct dma_async_tx_descriptor Guennadi Liakhovetski
2008-12-10 19:58 ` Dan Williams [this message]
2008-12-11 0:30 ` Guennadi Liakhovetski
2008-12-11 2:01 ` Dan Williams
2008-12-11 15:55 ` Guennadi Liakhovetski
2008-12-11 16:43 ` Dan Williams
2008-12-11 16:56 ` Guennadi Liakhovetski
2008-12-10 10:36 ` [PATCH 2/4 v2] i.MX31: Image Processing Unit DMA and IRQ drivers Guennadi Liakhovetski
2008-12-10 13:26 ` Dmitry Krivoschekov
2008-12-10 13:49 ` Guennadi Liakhovetski
2008-12-10 10:36 ` [PATCH 3/4 v2] i.MX31: framebuffer driver Guennadi Liakhovetski
2008-12-10 16:23 ` Herring Robert
2008-12-10 16:47 ` Guennadi Liakhovetski
2008-12-11 1:32 ` Herring Robert
2008-12-10 10:36 ` [PATCH 4/4 v2] i.MX31: platform bindings and initialisation for IPU and framebuffer drivers Guennadi Liakhovetski
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