From: Arnd Bergmann <arnd@arndb.de>
To: David Brown <davidb@codeaurora.org>
Cc: "Russell King - ARM Linux" <linux@arm.linux.org.uk>,
linaro-mm-sig@lists.linaro.org,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
linux-kernel@vger.kernel.org,
FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>,
Catalin Marinas <catalin.marinas@arm.com>,
KyongHo Cho <pullip.cho@samsung.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [Linaro-mm-sig] [RFC] ARM DMA mapping TODO, v1
Date: Mon, 2 May 2011 13:26:09 +0200 [thread overview]
Message-ID: <201105021326.09725.arnd@arndb.de> (raw)
In-Reply-To: <8yapqo1ogrk.fsf@huya.qualcomm.com>
On Monday 02 May 2011, David Brown wrote:
> I'll confirm this from the Qualcomm side as well. You cannot have
> multiple inconsistent mappings of the same page without having difficult
> to find problems.
I believe Catalin was referring to the case where you have only
one nonconsistent (cacheable) mapping plus multiple consistent
(cacheable) mappings. I don't think anyone has suggested doing
DMA to a page that has multiple nonconsistent mappings with
virtually indexed caches.
> The spec clarifications appear to give ways of dealing with it if it
> happens, and bounds on what can go wrong, but I wouldn't call it
> something we want to do normally. Corrupt data is arguably less of a
> problem than nasal demons, but still a problem.
Anything that has a theoretical chance of corrupting data is not an
option, but I'd really like to see what the clarified spec says
about this. Even if there is a way to legally leave a page for
dma_alloc_coherent in the linear mapping, it might turn out to
be harder to do than using highmem pages or unmapping supersections
at run time as was suggested.
Arnd
next prev parent reply other threads:[~2011-05-02 11:26 UTC|newest]
Thread overview: 99+ 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 20:09 ` [Linaro-mm-sig] " Jesse Barnes
2011-04-21 21:52 ` Zach Pfeffer
2011-04-22 0:34 ` KyongHo Cho
2011-04-26 14:29 ` Arnd Bergmann
2011-04-26 14:28 ` Arnd Bergmann
2011-04-26 14:26 ` Arnd Bergmann
2011-04-26 15:39 ` Jesse Barnes
2011-04-27 7:35 ` Russell King - ARM Linux
2011-04-27 8:56 ` Arnd Bergmann
2011-04-27 9:09 ` Russell King - ARM Linux
2011-04-27 11:02 ` Arnd Bergmann
2011-04-27 16:16 ` [Linaro-mm-sig] " Alex Deucher
2011-04-27 17:44 ` Anca Emanuel
2011-04-27 20:27 ` Russell King - ARM Linux
2011-04-27 20:16 ` Russell King - ARM Linux
2011-04-27 20:21 ` Arnd Bergmann
2011-04-27 20:26 ` Russell King - ARM Linux
2011-04-27 20:48 ` Arnd Bergmann
2011-04-27 21:41 ` Benjamin Herrenschmidt
2011-04-28 9:30 ` Russell King - ARM Linux
2011-04-28 21:07 ` Benjamin Herrenschmidt
2011-04-29 11:26 ` Arnd Bergmann
2011-04-29 11:47 ` Benjamin Herrenschmidt
2011-04-29 11:56 ` Alan Cox
2011-04-29 22:51 ` Benjamin Herrenschmidt
2011-04-29 12:06 ` [Linaro-mm-sig] " Thomas Hellstrom
2011-04-29 13:34 ` Jerome Glisse
2011-04-29 22:55 ` Benjamin Herrenschmidt
2011-04-29 22:53 ` Benjamin Herrenschmidt
2011-04-27 10:51 ` Marek Szyprowski
2011-04-27 21:37 ` Benjamin Herrenschmidt
2011-04-28 6:40 ` [Linaro-mm-sig] " Arnd Bergmann
2011-04-28 6:46 ` FUJITA Tomonori
2011-04-28 9:37 ` Russell King - ARM Linux
2011-04-28 10:32 ` [Linaro-mm-sig] " Marek Szyprowski
2011-04-28 10:51 ` Russell King - ARM Linux
2011-04-28 12:28 ` Arnd Bergmann
2011-04-28 13:15 ` Russell King - ARM Linux
2011-04-28 14:29 ` Arnd Bergmann
2011-04-28 14:34 ` Russell King - ARM Linux
2011-04-28 14:39 ` Arnd Bergmann
2011-04-28 14:58 ` Russell King - ARM Linux
2011-04-28 19:37 ` Jerome Glisse
2011-04-29 0:29 ` Benjamin Herrenschmidt
2011-04-29 5:50 ` Thomas Hellstrom
2011-04-29 7:35 ` Benjamin Herrenschmidt
2011-04-29 10:55 ` Thomas Hellstrom
2011-04-29 22:50 ` Benjamin Herrenschmidt
2011-04-29 16:27 ` Jesse Barnes
2011-04-29 22:46 ` Benjamin Herrenschmidt
2011-04-30 2:45 ` Jesse Barnes
2011-04-29 7:59 ` Russell King - ARM Linux
2011-04-29 16:32 ` Jesse Barnes
2011-04-29 18:29 ` Arnd Bergmann
2011-04-29 22:15 ` Russell King - ARM Linux
2011-05-02 4:42 ` David Brown
2011-05-02 11:26 ` Arnd Bergmann [this message]
2011-04-29 22:37 ` Benjamin Herrenschmidt
2011-04-29 13:42 ` Joerg Roedel
2011-04-29 14:19 ` Jerome Glisse
2011-04-29 15:37 ` Jordan Crouse
2011-04-28 14:38 ` FUJITA Tomonori
2011-04-29 0:25 ` Benjamin Herrenschmidt
2011-04-29 11:21 ` Arnd Bergmann
2011-04-28 10:41 ` Joerg Roedel
2011-04-28 11:01 ` Russell King - ARM Linux
2011-04-28 12:25 ` Joerg Roedel
2011-04-28 12:42 ` Russell King - ARM Linux
2011-04-28 12:59 ` Joerg Roedel
2011-04-28 13:02 ` Arnd Bergmann
2011-04-28 13:19 ` Russell King - ARM Linux
2011-04-28 13:56 ` Joerg Roedel
2011-04-28 14:30 ` Russell King - ARM Linux
2011-04-27 9:52 ` Catalin Marinas
2011-04-27 10:43 ` Arnd Bergmann
2011-04-27 11:08 ` Catalin Marinas
2011-04-28 0:15 ` Valdis.Kletnieks
2011-04-28 8:27 ` Catalin Marinas
2011-04-28 12:12 ` Arnd Bergmann
2011-04-28 12:36 ` Russell King - ARM Linux
2011-04-28 12:48 ` Arnd Bergmann
2011-05-03 14:45 ` Dave Martin
2011-04-29 15:41 ` [Linaro-mm-sig] " Arnd Bergmann
2011-04-29 16:42 ` Catalin Marinas
2011-05-03 15:05 ` [Linaro-mm-sig] " Laurent Pinchart
2011-05-03 15:31 ` Arnd Bergmann
2011-04-27 14:06 ` FUJITA Tomonori
2011-04-27 14:29 ` Catalin Marinas
2011-04-27 14:34 ` FUJITA Tomonori
2011-04-27 20:29 ` Russell King - ARM Linux
2011-04-27 21:45 ` Benjamin Herrenschmidt
2011-04-28 7:24 ` [Linaro-mm-sig] " KyongHo Cho
2011-04-28 8:31 ` Catalin Marinas
2011-04-27 21:31 ` Benjamin Herrenschmidt
2011-04-28 9:42 ` Russell King - ARM Linux
2011-04-28 10:27 ` Joerg Roedel
2011-04-28 12:15 ` Arnd Bergmann
-- strict thread matches above, loose matches on Subject: below --
2011-05-03 14:35 [Linaro-mm-sig] " Laurent Pinchart
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