From: Jesse Barnes <jbarnes@virtuousgeek.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [Linaro-mm-sig] [RFC] ARM DMA mapping TODO, v1
Date: Tue, 26 Apr 2011 08:39:22 -0700 [thread overview]
Message-ID: <20110426083922.344bd8d6@jbarnes-desktop> (raw)
In-Reply-To: <201104261626.20152.arnd@arndb.de>
On Tue, 26 Apr 2011 16:26:19 +0200
Arnd Bergmann <arnd@arndb.de> wrote:
> I don't thing that this argument has anything to do with what the
> underlying API should be, right? I can see this built on top of either
> the dma-mapping headers with extensions to map potentially uncached
> pages, and with the iommu API. Neither way would however save us from
> implementing the three items listed above.
Or simply extending the DMA mapping API to allow for allocations
without mapping. I was just worried you had a more traditional driver
model in mind (e.g. coherent alloc on the ring buffer, single mappings
for data buffers, all mapped in the kernel driver at allocation time).
The DMA API does have some advantages, in that arches already support
it, there's some infrastructure for handling per-bus mapping, etc., so
building on top of it is probably a good idea.
> It's certainly a good point to note that we should have a way to
> allocate pages for a device without mapping them into any address
> space right away. My feeling is still that the dma mapping API is
> the right place for this, because it is the only part of the kernel
> that has knowledge about whether a device needs uncached memory for
> coherent access, under what constraints it can map noncontiguous
> memory into its own address space, and what its addressing capabilities
> are (dma mask).
Right. Sometimes a device or platform can handle either cached or
uncached though, and we need userspace to decide on the best type for
performance reasons.
--
Jesse Barnes, Intel Open Source Technology Center
WARNING: multiple messages have this Message-ID (diff)
From: jbarnes@virtuousgeek.org (Jesse Barnes)
To: linux-arm-kernel@lists.infradead.org
Subject: [Linaro-mm-sig] [RFC] ARM DMA mapping TODO, v1
Date: Tue, 26 Apr 2011 08:39:22 -0700 [thread overview]
Message-ID: <20110426083922.344bd8d6@jbarnes-desktop> (raw)
In-Reply-To: <201104261626.20152.arnd@arndb.de>
On Tue, 26 Apr 2011 16:26:19 +0200
Arnd Bergmann <arnd@arndb.de> wrote:
> I don't thing that this argument has anything to do with what the
> underlying API should be, right? I can see this built on top of either
> the dma-mapping headers with extensions to map potentially uncached
> pages, and with the iommu API. Neither way would however save us from
> implementing the three items listed above.
Or simply extending the DMA mapping API to allow for allocations
without mapping. I was just worried you had a more traditional driver
model in mind (e.g. coherent alloc on the ring buffer, single mappings
for data buffers, all mapped in the kernel driver at allocation time).
The DMA API does have some advantages, in that arches already support
it, there's some infrastructure for handling per-bus mapping, etc., so
building on top of it is probably a good idea.
> It's certainly a good point to note that we should have a way to
> allocate pages for a device without mapping them into any address
> space right away. My feeling is still that the dma mapping API is
> the right place for this, because it is the only part of the kernel
> that has knowledge about whether a device needs uncached memory for
> coherent access, under what constraints it can map noncontiguous
> memory into its own address space, and what its addressing capabilities
> are (dma mask).
Right. Sometimes a device or platform can handle either cached or
uncached though, and we need userspace to decide on the best type for
performance reasons.
--
Jesse Barnes, Intel Open Source Technology Center
next prev parent reply other threads:[~2011-04-26 15:39 UTC|newest]
Thread overview: 198+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-21 19:29 [RFC] ARM DMA mapping TODO, v1 Arnd Bergmann
2011-04-21 19:29 ` Arnd Bergmann
2011-04-21 20:09 ` [Linaro-mm-sig] " Jesse Barnes
2011-04-21 20:09 ` Jesse Barnes
2011-04-21 21:52 ` Zach Pfeffer
2011-04-21 21:52 ` Zach Pfeffer
2011-04-22 0:34 ` KyongHo Cho
2011-04-22 0:34 ` KyongHo Cho
2011-04-26 14:29 ` Arnd Bergmann
2011-04-26 14:29 ` Arnd Bergmann
2011-04-26 14:28 ` Arnd Bergmann
2011-04-26 14:28 ` Arnd Bergmann
2011-04-26 14:26 ` Arnd Bergmann
2011-04-26 14:26 ` Arnd Bergmann
2011-04-26 15:39 ` Jesse Barnes [this message]
2011-04-26 15:39 ` Jesse Barnes
2011-04-27 7:35 ` Russell King - ARM Linux
2011-04-27 7:35 ` Russell King - ARM Linux
2011-04-27 8:56 ` Arnd Bergmann
2011-04-27 8:56 ` Arnd Bergmann
2011-04-27 9:09 ` Russell King - ARM Linux
2011-04-27 9:09 ` Russell King - ARM Linux
2011-04-27 11:02 ` Arnd Bergmann
2011-04-27 11:02 ` Arnd Bergmann
2011-04-27 16:16 ` [Linaro-mm-sig] " Alex Deucher
2011-04-27 16:16 ` Alex Deucher
2011-04-27 17:44 ` Anca Emanuel
2011-04-27 17:44 ` Anca Emanuel
2011-04-27 20:27 ` Russell King - ARM Linux
2011-04-27 20:27 ` Russell King - ARM Linux
2011-04-27 20:16 ` Russell King - ARM Linux
2011-04-27 20:16 ` Russell King - ARM Linux
2011-04-27 20:21 ` Arnd Bergmann
2011-04-27 20:21 ` Arnd Bergmann
2011-04-27 20:26 ` Russell King - ARM Linux
2011-04-27 20:26 ` Russell King - ARM Linux
2011-04-27 20:48 ` Arnd Bergmann
2011-04-27 20:48 ` Arnd Bergmann
2011-04-27 21:41 ` Benjamin Herrenschmidt
2011-04-27 21:41 ` Benjamin Herrenschmidt
2011-04-28 9:30 ` Russell King - ARM Linux
2011-04-28 9:30 ` Russell King - ARM Linux
2011-04-28 21:07 ` Benjamin Herrenschmidt
2011-04-28 21:07 ` Benjamin Herrenschmidt
2011-04-29 11:26 ` Arnd Bergmann
2011-04-29 11:26 ` Arnd Bergmann
2011-04-29 11:47 ` Benjamin Herrenschmidt
2011-04-29 11:47 ` Benjamin Herrenschmidt
2011-04-29 11:56 ` Alan Cox
2011-04-29 11:56 ` Alan Cox
2011-04-29 22:51 ` Benjamin Herrenschmidt
2011-04-29 22:51 ` Benjamin Herrenschmidt
2011-04-29 12:06 ` [Linaro-mm-sig] " Thomas Hellstrom
2011-04-29 12:06 ` Thomas Hellstrom
2011-04-29 13:34 ` Jerome Glisse
2011-04-29 13:34 ` Jerome Glisse
2011-04-29 22:55 ` Benjamin Herrenschmidt
2011-04-29 22:55 ` Benjamin Herrenschmidt
2011-04-29 22:53 ` Benjamin Herrenschmidt
2011-04-29 22:53 ` Benjamin Herrenschmidt
2011-04-27 10:51 ` Marek Szyprowski
2011-04-27 10:51 ` Marek Szyprowski
2011-04-27 21:37 ` Benjamin Herrenschmidt
2011-04-27 21:37 ` Benjamin Herrenschmidt
2011-04-28 6:40 ` [Linaro-mm-sig] " Arnd Bergmann
2011-04-28 6:40 ` Arnd Bergmann
2011-04-28 6:46 ` FUJITA Tomonori
2011-04-28 6:46 ` FUJITA Tomonori
2011-04-28 9:37 ` Russell King - ARM Linux
2011-04-28 9:37 ` Russell King - ARM Linux
2011-04-28 10:32 ` [Linaro-mm-sig] " Marek Szyprowski
2011-04-28 10:32 ` Marek Szyprowski
2011-04-28 10:51 ` Russell King - ARM Linux
2011-04-28 10:51 ` Russell King - ARM Linux
2011-04-28 12:28 ` Arnd Bergmann
2011-04-28 12:28 ` Arnd Bergmann
2011-04-28 13:15 ` Russell King - ARM Linux
2011-04-28 13:15 ` Russell King - ARM Linux
2011-04-28 14:29 ` Arnd Bergmann
2011-04-28 14:29 ` Arnd Bergmann
2011-04-28 14:34 ` Russell King - ARM Linux
2011-04-28 14:34 ` Russell King - ARM Linux
2011-04-28 14:39 ` Arnd Bergmann
2011-04-28 14:39 ` Arnd Bergmann
2011-04-28 14:58 ` Russell King - ARM Linux
2011-04-28 14:58 ` Russell King - ARM Linux
2011-04-28 19:37 ` Jerome Glisse
2011-04-28 19:37 ` Jerome Glisse
2011-04-29 0:29 ` Benjamin Herrenschmidt
2011-04-29 0:29 ` Benjamin Herrenschmidt
2011-04-29 5:50 ` Thomas Hellstrom
2011-04-29 5:50 ` Thomas Hellstrom
2011-04-29 7:35 ` Benjamin Herrenschmidt
2011-04-29 7:35 ` Benjamin Herrenschmidt
2011-04-29 10:55 ` Thomas Hellstrom
2011-04-29 10:55 ` Thomas Hellstrom
2011-04-29 22:50 ` Benjamin Herrenschmidt
2011-04-29 22:50 ` Benjamin Herrenschmidt
2011-04-29 16:27 ` Jesse Barnes
2011-04-29 16:27 ` Jesse Barnes
2011-04-29 22:46 ` Benjamin Herrenschmidt
2011-04-29 22:46 ` Benjamin Herrenschmidt
2011-04-30 2:45 ` Jesse Barnes
2011-04-30 2:45 ` Jesse Barnes
2011-04-29 7:59 ` Russell King - ARM Linux
2011-04-29 7:59 ` Russell King - ARM Linux
2011-04-29 16:32 ` Jesse Barnes
2011-04-29 16:32 ` Jesse Barnes
2011-04-29 18:29 ` Arnd Bergmann
2011-04-29 18:29 ` Arnd Bergmann
2011-04-29 22:15 ` Russell King - ARM Linux
2011-04-29 22:15 ` Russell King - ARM Linux
2011-05-02 4:42 ` David Brown
2011-05-02 4:42 ` David Brown
2011-05-02 11:26 ` Arnd Bergmann
2011-05-02 11:26 ` Arnd Bergmann
2011-04-29 22:37 ` Benjamin Herrenschmidt
2011-04-29 22:37 ` Benjamin Herrenschmidt
2011-04-29 13:42 ` Joerg Roedel
2011-04-29 13:42 ` Joerg Roedel
2011-04-29 14:19 ` Jerome Glisse
2011-04-29 14:19 ` Jerome Glisse
2011-04-29 15:37 ` Jordan Crouse
2011-04-29 15:37 ` Jordan Crouse
2011-04-28 14:38 ` FUJITA Tomonori
2011-04-28 14:38 ` FUJITA Tomonori
2011-04-29 0:25 ` Benjamin Herrenschmidt
2011-04-29 0:25 ` Benjamin Herrenschmidt
2011-04-29 11:21 ` Arnd Bergmann
2011-04-29 11:21 ` Arnd Bergmann
2011-04-28 10:41 ` Joerg Roedel
2011-04-28 10:41 ` Joerg Roedel
2011-04-28 11:01 ` Russell King - ARM Linux
2011-04-28 11:01 ` Russell King - ARM Linux
2011-04-28 12:25 ` Joerg Roedel
2011-04-28 12:25 ` Joerg Roedel
2011-04-28 12:42 ` Russell King - ARM Linux
2011-04-28 12:42 ` Russell King - ARM Linux
2011-04-28 12:59 ` Joerg Roedel
2011-04-28 12:59 ` Joerg Roedel
2011-04-28 13:02 ` Arnd Bergmann
2011-04-28 13:02 ` Arnd Bergmann
2011-04-28 13:19 ` Russell King - ARM Linux
2011-04-28 13:19 ` Russell King - ARM Linux
2011-04-28 13:56 ` Joerg Roedel
2011-04-28 13:56 ` Joerg Roedel
2011-04-28 14:30 ` Russell King - ARM Linux
2011-04-28 14:30 ` Russell King - ARM Linux
2011-04-27 9:52 ` Catalin Marinas
2011-04-27 9:52 ` Catalin Marinas
2011-04-27 10:43 ` Arnd Bergmann
2011-04-27 10:43 ` Arnd Bergmann
2011-04-27 11:08 ` Catalin Marinas
2011-04-27 11:08 ` Catalin Marinas
2011-04-28 0:15 ` Valdis.Kletnieks
2011-04-28 0:15 ` Valdis.Kletnieks at vt.edu
2011-04-28 8:27 ` Catalin Marinas
2011-04-28 8:27 ` Catalin Marinas
2011-04-28 12:12 ` Arnd Bergmann
2011-04-28 12:12 ` Arnd Bergmann
2011-04-28 12:36 ` Russell King - ARM Linux
2011-04-28 12:36 ` Russell King - ARM Linux
2011-04-28 12:48 ` Arnd Bergmann
2011-04-28 12:48 ` Arnd Bergmann
2011-05-03 14:45 ` Dave Martin
2011-05-03 14:45 ` Dave Martin
2011-04-29 15:41 ` [Linaro-mm-sig] " Arnd Bergmann
2011-04-29 15:41 ` Arnd Bergmann
2011-04-29 16:42 ` Catalin Marinas
2011-04-29 16:42 ` Catalin Marinas
2011-05-03 15:05 ` [Linaro-mm-sig] " Laurent Pinchart
2011-05-03 15:05 ` Laurent Pinchart
2011-05-03 15:31 ` Arnd Bergmann
2011-05-03 15:31 ` Arnd Bergmann
2011-04-27 14:06 ` FUJITA Tomonori
2011-04-27 14:06 ` FUJITA Tomonori
2011-04-27 14:29 ` Catalin Marinas
2011-04-27 14:29 ` Catalin Marinas
2011-04-27 14:34 ` FUJITA Tomonori
2011-04-27 14:34 ` FUJITA Tomonori
2011-04-27 20:29 ` Russell King - ARM Linux
2011-04-27 20:29 ` Russell King - ARM Linux
2011-04-27 21:45 ` Benjamin Herrenschmidt
2011-04-27 21:45 ` Benjamin Herrenschmidt
2011-04-28 7:24 ` [Linaro-mm-sig] " KyongHo Cho
2011-04-28 7:24 ` KyongHo Cho
2011-04-28 8:31 ` Catalin Marinas
2011-04-28 8:31 ` Catalin Marinas
2011-04-27 21:31 ` Benjamin Herrenschmidt
2011-04-27 21:31 ` Benjamin Herrenschmidt
2011-04-28 9:42 ` Russell King - ARM Linux
2011-04-28 9:42 ` Russell King - ARM Linux
2011-04-28 10:27 ` Joerg Roedel
2011-04-28 10:27 ` Joerg Roedel
2011-04-28 12:15 ` Arnd Bergmann
2011-04-28 12:15 ` Arnd Bergmann
2011-05-03 14:35 [Linaro-mm-sig] " Laurent Pinchart
2011-05-03 14:35 ` Laurent Pinchart
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=20110426083922.344bd8d6@jbarnes-desktop \
--to=jbarnes@virtuousgeek.org \
--cc=arnd@arndb.de \
--cc=linaro-mm-sig@lists.linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.