From: Marek Szyprowski <m.szyprowski@samsung.com>
To: 'Krishna Reddy' <vdumpa@nvidia.com>
Cc: linux-arch@vger.kernel.org,
'Russell King - ARM Linux' <linux@arm.linux.org.uk>,
'Arnd Bergmann' <arnd@arndb.de>, 'Joerg Roedel' <joro@8bytes.org>,
linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org,
'Kyungmin Park' <kyungmin.park@samsung.com>,
Andrzej Pietrasiewicz <andrzej.p@samsung.com>,
'Chunsang Jeong' <chunsang.jeong@linaro.org>,
linux-arm-kernel@lists.infradead.org
Subject: RE: [Linaro-mm-sig] [PATCH 1/2] ARM: initial proof-of-concept IOMMU mapper for DMA-mapping
Date: Wed, 12 Oct 2011 07:49:34 +0200 [thread overview]
Message-ID: <00e501cc88a2$b82fc680$288f5380$%szyprowski@samsung.com> (raw)
In-Reply-To: <401E54CE964CD94BAE1EB4A729C7087E3722519BF4@HQMAIL04.nvidia.com>
Hello,
On Wednesday, October 12, 2011 3:35 AM Krishna Reddy wrote:
> >>It looks that You have simplified arm_iommu_map_sg() function too much.
> >>The main advantage of the iommu is to map scattered memory pages into
> >>contiguous dma address space. DMA-mapping is allowed to merge consecutive
> >>entries in the scatter list if hardware supports that.
> >>http://article.gmane.org/gmane.linux.kernel/1128416
> >I would update arm_iommu_map_sg() back to coalesce the sg list.
> >>MMC drivers seem to be aware of coalescing the SG entries together as they are using
> dma_sg_len().
>
> I have updated the arm_iommu_map_sg() back to coalesce and fixed the issues with it. During
> testing, I found out that mmc host driver doesn't support buffers bigger than 64K. To get the
> device working, I had to break the sg entries coalesce when dma_length is about to go beyond
> 64KB. Looks like Mmc host driver(sdhci.c) need to be fixed to handle buffers bigger than 64KB.
> Should the clients be forced to handle bigger buffers or is there any better way to handle
> these kind of issues?
There is struct device_dma_parameters *dma_parms member of struct device. You can specify
maximum segment size for the dma_map_sg function. This will of course complicate this function
even more...
Best regards
--
Marek Szyprowski
Samsung Poland R&D Center
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2011-10-12 5:49 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-02 13:56 [RFC 0/2 v2] ARM: DMA-mapping & IOMMU integration Marek Szyprowski
2011-09-02 13:56 ` [PATCH 1/2] ARM: initial proof-of-concept IOMMU mapper for DMA-mapping Marek Szyprowski
2011-09-08 16:41 ` [Linaro-mm-sig] " Laura Abbott
2011-09-21 14:50 ` Marek Szyprowski
2011-10-10 21:56 ` Krishna Reddy
2011-10-11 8:19 ` Marek Szyprowski
2011-10-11 18:13 ` Krishna Reddy
2011-10-12 1:34 ` Krishna Reddy
2011-10-12 5:49 ` Marek Szyprowski [this message]
2011-10-12 7:02 ` Krishna Reddy
2011-10-13 0:18 ` Krishna Reddy
2011-10-17 14:07 ` Marek Szyprowski
2011-09-02 13:56 ` [PATCH 2/2] ARM: Samsung: update/rewrite Samsung SYSMMU (IOMMU) driver Marek Szyprowski
2011-09-05 18:21 ` Ohad Ben-Cohen
2011-09-06 10:27 ` KyongHo Cho
2011-09-06 12:35 ` [Linaro-mm-sig] " Ohad Ben-Cohen
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='00e501cc88a2$b82fc680$288f5380$%szyprowski@samsung.com' \
--to=m.szyprowski@samsung.com \
--cc=andrzej.p@samsung.com \
--cc=arnd@arndb.de \
--cc=chunsang.jeong@linaro.org \
--cc=joro@8bytes.org \
--cc=kyungmin.park@samsung.com \
--cc=linaro-mm-sig@lists.linaro.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-mm@kvack.org \
--cc=linux@arm.linux.org.uk \
--cc=vdumpa@nvidia.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).