From: arnd@arndb•de (Arnd Bergmann)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 1/2] arm: mvebu: increase atomic coherent pool size for armada 370/XP
Date: Thu, 25 Oct 2012 13:46:41 +0000 [thread overview]
Message-ID: <201210251346.41596.arnd@arndb.de> (raw)
In-Reply-To: <20121025134352.16a8ef81@skate>
On Thursday 25 October 2012, Thomas Petazzoni wrote:
> On Thu, 25 Oct 2012 11:27:36 +0000, Arnd Bergmann wrote:
> > On Wednesday 24 October 2012, Gregory CLEMENT wrote:
> > > For Armada 370/XP we have the same problem that for the commit
> > > cb01b63, so we applied the same solution: "The default 256 KiB
> > > coherent pool may be too small for some of the Kirkwood devices, so
> > > increase it to make sure that devices will be able to allocate their
> > > buffers with GFP_ATOMIC flag"
> > >
> > > Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons•com>
> >
> > Do you know why the ATA driver needs this? I find it surprising that
> > it's necessary, so I'd like to make sure we're not just working around
> > a device driver bug here.
>
> The sata_mv driver create dma_pool and allocate objects from them, and
> all the memory allocated for dma_pools is allocated using
> dma_alloc_coherent(), and I guess the driver is using too much of them.
>
> Seems like the driver is too lazy and allocates everything coherent to
> avoid the hassle of doing dma_map/dma_unmap operations when needed, but
> I haven't looked in details at the driver yet to see if it would be
> possible to switch those DMA coherent allocations into non-coherent
> allocations + appropriate calls to the DMA operations.
Using coherent allocations is fine, I was wondering whether they need
to be atomic or not.
> That said, that's for sure a larger task than just enabling SATA on
> Armada 370/XP, so I would advocate to handle this problem separately.
Agreed.
Arnd
next prev parent reply other threads:[~2012-10-25 13:46 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-24 13:49 [PATCH 0/2] Adding SATA support for Armada 370/XP Gregory CLEMENT
2012-10-24 13:49 ` [PATCH 1/2] arm: mvebu: increase atomic coherent pool size for armada 370/XP Gregory CLEMENT
2012-10-25 5:29 ` Marek Szyprowski
2012-10-25 11:27 ` Arnd Bergmann
2012-10-25 11:43 ` Thomas Petazzoni
2012-10-25 13:46 ` Arnd Bergmann [this message]
2012-10-25 14:09 ` Thomas Petazzoni
2012-10-30 7:19 ` Marek Szyprowski
2012-10-24 13:49 ` [PATCH 2/2] arm: mvebu: adding SATA support: dt binding and config update Gregory CLEMENT
2012-10-24 14:01 ` Thomas Petazzoni
2012-10-24 14:05 ` Gregory CLEMENT
2012-10-25 13:18 ` Jason Cooper
2012-10-25 13:21 ` Thomas Petazzoni
2012-10-25 13:34 ` Gregory CLEMENT
2012-10-25 13:57 ` Rob Herring
2012-10-25 16:00 ` Gregory CLEMENT
2012-10-25 13:35 ` Jason Cooper
2012-10-25 13:53 ` Rob Herring
2012-10-25 14:11 ` Gregory CLEMENT
2012-10-25 14:27 ` Rob Herring
2012-10-24 14:08 ` Andrew Lunn
2012-10-24 14:45 ` Gregory CLEMENT
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