From: Christoph Hellwig <hch@lst.de>
To: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Jonas Bonn <jonas@southpole.se>,
linux-xtensa@linux-xtensa.org, linux-parisc@vger.kernel.org,
Vineet Gupta <vgupta@synopsys.com>, Helge Deller <deller@gmx.de>,
linux-kernel@vger.kernel.org,
Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
iommu@lists.linux-foundation.org, openrisc@lists.librecores.org,
Stafford Horne <shorne@gmail.com>,
linux-snps-arc@lists.infradead.org,
Christoph Hellwig <hch@lst.de>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/7] arm-nommu: remove the partial DMA_ATTR_NON_CONSISTENT support
Date: Tue, 25 Jun 2019 08:13:32 +0200 [thread overview]
Message-ID: <20190625061332.GC28986@lst.de> (raw)
In-Reply-To: <a017e704-c6c4-7718-7f8b-eb8a0eced14d@arm.com>
On Mon, Jun 24, 2019 at 03:23:08PM +0100, Vladimir Murzin wrote:
> On 6/14/19 3:44 PM, Christoph Hellwig wrote:
> > The arm-nommu DMA code supports DMA_ATTR_NON_CONSISTENT allocations, but
> > does not provide a cache_sync operation. This means any user of it
> > will never be able to actually transfer cache ownership and thus cause
> > coherency bugs.
>
> By the way, Documentation/DMA-attributes.txt doesn't specify cache_sync() as
> requirement for DMA_ATTR_NON_CONSISTENT it only states that it is responsibility
> of the driver to have all the correct and necessary sync points.
True. dma_cache_sync has always been a rather odd interface, as it
doesn't specify in what direction we need to sync and doesn't
participate in our ownership protocol. So my mid-term plan is to kill
it off and replace it with the existing dma_sync_* helpers. This
series is the first step towards that.
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
next prev parent reply other threads:[~2019-06-25 6:14 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-14 14:44 handle "special" dma allocation in common code Christoph Hellwig
2019-06-14 14:44 ` [PATCH 1/7] arm-nommu: remove the partial DMA_ATTR_NON_CONSISTENT support Christoph Hellwig
2019-06-24 14:23 ` Vladimir Murzin
2019-06-25 6:13 ` Christoph Hellwig [this message]
2019-06-14 14:44 ` [PATCH 2/7] arc: " Christoph Hellwig
2019-06-14 14:44 ` [PATCH 3/7] openrisc: " Christoph Hellwig
2019-06-16 9:17 ` Stafford Horne
2019-06-14 14:44 ` [PATCH 4/7] dma-mapping: add a dma_alloc_need_uncached helper Christoph Hellwig
2019-06-14 14:44 ` [PATCH 5/7] dma-direct: handle DMA_ATTR_NON_CONSISTENT in common code Christoph Hellwig
2019-06-16 10:08 ` Hillf Danton
2019-06-25 6:11 ` Christoph Hellwig
2019-06-25 12:23 ` Helge Deller
2019-06-25 12:28 ` Christoph Hellwig
2019-06-14 14:44 ` [PATCH 6/7] dma-direct: handle DMA_ATTR_NO_KERNEL_MAPPING " Christoph Hellwig
2019-06-29 15:09 ` Guenter Roeck
2019-06-14 14:44 ` [PATCH 7/7] arc: use the generic remapping allocator for coherent DMA allocations Christoph Hellwig
2019-06-14 18:05 ` Eugeniy Paltsev
2019-06-15 8:35 ` hch
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190625061332.GC28986@lst.de \
--to=hch@lst.de \
--cc=deller@gmx.de \
--cc=iommu@lists.linux-foundation.org \
--cc=jonas@southpole.se \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-parisc@vger.kernel.org \
--cc=linux-snps-arc@lists.infradead.org \
--cc=linux-xtensa@linux-xtensa.org \
--cc=openrisc@lists.librecores.org \
--cc=shorne@gmail.com \
--cc=stefan.kristiansson@saunalahti.fi \
--cc=vgupta@synopsys.com \
--cc=vladimir.murzin@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).