From: Marek Szyprowski <m.szyprowski@samsung.com>
To: 'Arnd Bergmann' <arnd@arndb.de>
Cc: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-media@vger.kernel.org, linux-mm@kvack.org,
linaro-mm-sig@lists.linaro.org,
'Michal Nazarewicz' <mina86@mina86.com>,
'Kyungmin Park' <kyungmin.park@samsung.com>,
'Russell King' <linux@arm.linux.org.uk>,
'Andrew Morton' <akpm@linux-foundation.org>,
'KAMEZAWA Hiroyuki' <kamezawa.hiroyu@jp.fujitsu.com>,
'Ankita Garg' <ankita@in.ibm.com>,
'Daniel Walker' <dwalker@codeaurora.org>,
'Mel Gorman' <mel@csn.ul.ie>,
'Jesse Barker' <jesse.barker@linaro.org>,
'Jonathan Corbet' <corbet@lwn.net>,
'Shariq Hasnain' <shariq.hasnain@linaro.org>,
'Chunsang Jeong' <chunsang.jeong@linaro.org>
Subject: RE: [PATCH 7/9] ARM: DMA: steal memory for DMA coherent mappings
Date: Tue, 16 Aug 2011 12:17:30 +0200 [thread overview]
Message-ID: <004301cc5bfd$b50048d0$1f00da70$%szyprowski@samsung.com> (raw)
In-Reply-To: <201108121453.05898.arnd@arndb.de>
Hello,
On Friday, August 12, 2011 2:53 PM Arnd Bergmann wrote:
> On Friday 12 August 2011, Marek Szyprowski wrote:
> >
> > From: Russell King <rmk+kernel@arm.linux.org.uk>
> >
> > Steal memory from the kernel to provide coherent DMA memory to drivers.
> > This avoids the problem with multiple mappings with differing attributes
> > on later CPUs.
> >
> > Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
> > [m.szyprowski: rebased onto 3.1-rc1]
> > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
>
> Hi Marek,
>
> Is this the same patch that Russell had to revert because it didn't
> work on some of the older machines, in particular those using
> dmabounce?
Yes.
> I thought that our discussion ended with the plan to use this only
> for ARMv6+ (which has a problem with double mapping) but not on ARMv5
> and below (which don't have this problem but might need dmabounce).
Ok, my fault. I've forgot to mention that this patch was almost ready
during Linaro meeting, but I didn't manage to post it that time. Of course
it doesn't fulfill all the agreements from that discussion.
I was only unsure if we should care about the case where CMA is not enabled
for ARMv6+ or not. This patch was prepared in assumption that
dma_alloc_coherent should work in both cases - with and without CMA.
Now I assume that for ARMv6+ the CMA should be enabled unconditionally.
Best regards
--
Marek Szyprowski
Samsung Poland R&D Center
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next prev parent reply other threads:[~2011-08-16 10:18 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-12 10:58 [PATCHv14 0/9] Contiguous Memory Allocator Marek Szyprowski
2011-08-12 10:58 ` [PATCH 1/9] mm: move some functions from memory_hotplug.c to page_isolation.c Marek Szyprowski
2011-08-12 10:58 ` [PATCH 2/9] mm: alloc_contig_freed_pages() added Marek Szyprowski
2011-08-12 10:58 ` [PATCH 3/9] mm: alloc_contig_range() added Marek Szyprowski
2011-08-12 10:58 ` [PATCH 4/9] mm: MIGRATE_CMA migration type added Marek Szyprowski
2011-08-12 10:58 ` [PATCH 5/9] mm: MIGRATE_CMA isolation functions added Marek Szyprowski
2011-08-12 10:58 ` [PATCH 6/9] drivers: add Contiguous Memory Allocator Marek Szyprowski
2011-08-12 10:58 ` [PATCH 7/9] ARM: DMA: steal memory for DMA coherent mappings Marek Szyprowski
2011-08-12 12:53 ` Arnd Bergmann
2011-08-14 7:52 ` Russell King - ARM Linux
2011-08-16 13:28 ` Arnd Bergmann
2011-08-16 13:55 ` Russell King - ARM Linux
2011-08-16 14:26 ` Arnd Bergmann
2011-08-17 8:01 ` Marek Szyprowski
2011-08-17 12:28 ` Arnd Bergmann
2011-08-17 13:06 ` Marek Szyprowski
2011-08-18 8:27 ` Tixy
2011-08-17 12:49 ` Marek Szyprowski
2011-08-16 10:17 ` Marek Szyprowski [this message]
2011-08-12 10:58 ` [PATCH 8/9] ARM: integrate CMA with DMA-mapping subsystem Marek Szyprowski
2011-08-12 15:00 ` Arnd Bergmann
2011-08-16 9:29 ` Marek Szyprowski
2011-08-16 13:14 ` Arnd Bergmann
2011-08-12 10:58 ` [PATCH 9/9] ARM: S5PV210: example of CMA private area for FIMC device on Goni board Marek Szyprowski
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