From: Stephen Rothwell <sfr@canb.auug.org.au>
To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: linux-arm-kernel@lists.infradead.org,
linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org,
linux-arch@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
iommu@lists.linux-foundation.org,
Kyungmin Park <kyungmin.park@samsung.com>,
Arnd Bergmann <arnd@arndb.de>, Joerg Roedel <joro@8bytes.org>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Shariq Hasnain <shariq.hasnain@linaro.org>,
Chunsang Jeong <chunsang.jeong@linaro.org>,
Krishna Reddy <vdumpa@nvidia.com>,
KyongHo Cho <pullip.cho@samsung.com>,
Andrzej Pietrasiewicz <andrzej.p@samsung.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH 6/8] common: dma-mapping: change alloc/free_coherent method to more generic alloc/free_attrs
Date: Mon, 12 Dec 2011 09:45:59 +1100 [thread overview]
Message-ID: <20111212094559.e4af7c0ab6633de400487fde@canb.auug.org.au> (raw)
In-Reply-To: <1323448798-18184-7-git-send-email-m.szyprowski@samsung.com>
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Hi Marek,
On Fri, 09 Dec 2011 17:39:56 +0100 Marek Szyprowski <m.szyprowski@samsung.com> wrote:
>
> Introduce new alloc/free/mmap methods that take attributes argument.
> alloc/free_coherent can be implemented on top of the new alloc/free
> calls with NULL attributes. dma_alloc_non_coherent can be implemented
> using DMA_ATTR_NONCOHERENT attribute, dma_alloc_writecombine can also
> use separate DMA_ATTR_WRITECOMBINE attribute. This way the drivers will
> get more generic, platform independent way of allocating dma memory
> buffers with specific parameters.
>
> One more attribute can be usefull: DMA_ATTR_NOKERNELVADDR. Buffers with
> such attribute will not have valid kernel virtual address. They might be
> usefull for drivers that only exports the DMA buffers to userspace (like
> for example V4L2 or ALSA).
>
> mmap method is introduced to let the drivers create a user space mapping
> for a DMA buffer in generic, architecture independent way.
>
> TODO: update all dma_map_ops clients for all architectures
To give everyone some chance, you should come up with a transition plan
rather than this "attempt to fix everyone at once" approach. You could
(for example) just add the new methods now and only remove them in the
following merge window when all the architectures have had a chance to
migrate.
And, in fact, (as I presume you know) this patch just breaks everyone
with no attempt to cope.
--
Cheers,
Stephen Rothwell sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/
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next prev parent reply other threads:[~2011-12-11 22:46 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-09 16:39 [PATCH 0/8 v4] ARM: DMA-mapping framework redesign Marek Szyprowski
2011-12-09 16:39 ` [PATCH 1/8] ARM: dma-mapping: remove offset parameter to prepare for generic dma_ops Marek Szyprowski
2011-12-09 16:39 ` [PATCH 2/8] ARM: dma-mapping: use asm-generic/dma-mapping-common.h Marek Szyprowski
2011-12-09 16:39 ` [PATCH 3/8] ARM: dma-mapping: implement dma sg methods on top of any generic dma ops Marek Szyprowski
2011-12-09 16:39 ` [PATCH 4/8] ARM: dma-mapping: move all dma bounce code to separate dma ops structure Marek Szyprowski
2011-12-09 16:39 ` [PATCH 5/8] ARM: dma-mapping: remove redundant code and cleanup Marek Szyprowski
2011-12-09 16:39 ` [PATCH 6/8] common: dma-mapping: change alloc/free_coherent method to more generic alloc/free_attrs Marek Szyprowski
2011-12-11 22:45 ` Stephen Rothwell [this message]
2011-12-14 12:37 ` Marek Szyprowski
2011-12-09 16:39 ` [PATCH 7/8] ARM: dma-mapping: use alloc, mmap, free from dma_ops Marek Szyprowski
2011-12-09 16:39 ` [PATCH 8/8] ARM: dma-mapping: add support for IOMMU mapper Marek Szyprowski
2012-01-09 15:49 ` [PATCH 8/8 RESEND] " Marek Szyprowski
2012-01-25 12:59 ` Russell King - ARM Linux
2012-01-26 8:09 ` Marek Szyprowski
2012-01-25 12:47 ` [PATCH 8/8] " Hiroshi Doyu
2012-01-26 7:46 ` Marek Szyprowski
2012-01-10 8:42 ` [PATCH 0/8 v4] ARM: DMA-mapping framework redesign Marek Szyprowski
-- strict thread matches above, loose matches on Subject: below --
2011-10-18 17:19 [PATCH 0/8 v3] " Marek Szyprowski
2011-10-18 17:19 ` [PATCH 6/8] common: dma-mapping: change alloc/free_coherent method to more generic alloc/free_attrs Marek Szyprowski
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