From: Mike Frysinger <vapier.adi@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Oskar Schirmer" <os@emlix.com>,
"Michael Hennerich" <Michael.Hennerich@analog.com>,
"Dmitry Torokhov" <dmitry.torokhov@gmail.com>,
"Mike Frysinger" <vapier@gentoo.org>,
linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
"Daniel Glöckner" <dg@emlix.com>,
"Oliver Schneidewind" <osw@emlix.com>,
"Johannes Weiner" <jw@emlix.com>
Subject: Re: [PATCH v3] ad7877: keep dma rx buffers in seperate cache lines
Date: Mon, 10 May 2010 17:27:30 -0400 [thread overview]
Message-ID: <AANLkTinp6wpCTgvq2Vqj4GZRcsM8-vdOm4oI6MMKaedj@mail.gmail.com> (raw)
In-Reply-To: <20100510142225.4bf215ef.akpm@linux-foundation.org>
On Mon, May 10, 2010 at 17:22, Andrew Morton wrote:
> On Mon, 10 May 2010 12:42:34 +0200 "Oskar Schirmer" wrote:
>> With dma based spi transmission, data corruption
>> is observed occasionally. With dma buffers located
>> right next to msg and xfer fields, cache lines
>> correctly flushed in preparation for dma usage
>> may be polluted again when writing to fields
>> in the same cache line.
>>
>> Make sure cache fields used with dma do not
>> share cache lines with fields changed during
>> dma handling. As both fields are part of a
>> struct that is allocated via kzalloc, thus
>> cache aligned, moving the fields to the 1st
>> position and insert padding for alignment
>> does the job.
>
> This sounds odd. Doesn't it imply that some code somewhere is missing
> some DMA synchronisation actions?
i think it's kind of dumb and induces this sort of bug
semi-frequently, but it is what the current DMA API requires (see like
Documentation/spi/spi-summary)
-mike
next prev parent reply other threads:[~2010-05-10 21:27 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-06 10:37 [PATCH] ad7877: fix spi word size to 16 bit Oskar Schirmer
2010-05-06 10:37 ` [PATCH] ad7877: keep dma rx buffers in seperate cache lines Oskar Schirmer
2010-05-06 18:46 ` Mike Frysinger
2010-05-07 10:15 ` Oskar Schirmer
2010-05-07 18:28 ` Mike Frysinger
2010-05-08 22:32 ` Johannes Weiner
2010-05-09 4:45 ` Mike Frysinger
2010-05-09 8:50 ` Oskar Schirmer
2010-05-07 12:07 ` Johannes Weiner
2010-05-10 10:34 ` [PATCH v2] " Oskar Schirmer
2010-05-10 10:42 ` [PATCH v3] " Oskar Schirmer
2010-05-10 16:39 ` Mike Frysinger
2010-05-10 20:54 ` Dmitry Torokhov
2010-05-10 21:22 ` Andrew Morton
2010-05-10 21:27 ` Mike Frysinger [this message]
2010-05-11 6:05 ` Dmitry Torokhov
2010-05-11 6:11 ` Mike Frysinger
2010-05-11 3:20 ` Andrew Morton
2010-05-11 6:21 ` Dmitry Torokhov
2010-05-11 6:23 ` Mike Frysinger
2010-05-11 6:33 ` Dmitry Torokhov
2010-05-11 6:37 ` Mike Frysinger
2010-05-11 6:42 ` Pekka Enberg
2010-05-11 13:57 ` Christoph Lameter
2010-05-11 16:52 ` Dmitry Torokhov
2010-05-11 17:31 ` Mike Frysinger
2010-05-11 18:59 ` Pekka Enberg
2010-05-11 20:03 ` Mike Frysinger
2010-05-11 20:07 ` Matt Mackall
2010-05-11 20:10 ` Mike Frysinger
2010-05-11 20:21 ` Christoph Lameter
2010-05-11 20:34 ` Mike Frysinger
2010-05-11 20:38 ` Pekka Enberg
2010-05-11 20:43 ` Mike Frysinger
2010-05-11 20:47 ` Pekka Enberg
2010-05-13 6:21 ` Paul Mundt
2010-05-11 20:46 ` Christoph Lameter
2010-05-11 20:54 ` Mike Frysinger
2010-05-11 21:01 ` Pekka Enberg
2010-05-11 21:11 ` Mike Frysinger
2010-05-12 1:58 ` FUJITA Tomonori
[not found] ` <20100511214836.GH1726@emlix.com>
2010-05-11 21:53 ` Dmitry Torokhov
2010-05-11 22:39 ` Mike Frysinger
2010-05-12 2:07 ` [LKML] " Marc Gauthier
2010-05-12 3:03 ` Nick Piggin
2010-05-12 3:23 ` FUJITA Tomonori
2010-05-12 4:35 ` Mike Frysinger
2010-05-12 5:28 ` FUJITA Tomonori
2010-05-12 14:37 ` Mike Frysinger
2010-05-12 18:11 ` Dmitry Torokhov
2010-05-12 18:28 ` Mike Frysinger
2010-05-12 10:36 ` Johannes Weiner
2010-05-12 12:35 ` Marc Gauthier
2010-05-12 14:36 ` Mike Frysinger
2010-05-19 12:48 ` David Woodhouse
2010-05-19 13:07 ` Nick Piggin
2010-05-19 13:17 ` David Woodhouse
2010-05-19 13:36 ` Nick Piggin
2010-05-19 13:44 ` Johannes Weiner
2010-05-19 13:52 ` Nick Piggin
2010-05-19 14:38 ` FUJITA Tomonori
2010-05-19 14:58 ` David Woodhouse
2010-05-20 4:42 ` FUJITA Tomonori
2010-05-19 16:37 ` Dmitry Torokhov
2010-05-19 15:00 ` Johannes Weiner
2010-05-17 6:12 ` Michal Simek
2010-05-19 13:00 ` David Woodhouse
2010-05-11 22:37 ` Alan Cox
2010-05-11 20:22 ` Pekka Enberg
2010-05-11 14:12 ` Oskar Schirmer
2010-05-06 11:18 ` [PATCH] ad7877: fix spi word size to 16 bit Hennerich, Michael
2010-05-06 18:26 ` Mike Frysinger
2010-05-07 9:41 ` Daniel Glöckner
2010-05-07 18:23 ` Mike Frysinger
2010-05-13 7:53 ` Dmitry Torokhov
2010-05-15 18:15 ` Oskar Schirmer
2010-05-16 19:25 ` Mike Frysinger
2010-05-17 7:29 ` Oskar Schirmer
2010-05-17 8:14 ` Hennerich, Michael
2010-05-17 8:41 ` Oskar Schirmer
2010-05-17 23:49 ` Mike Frysinger
2010-05-18 0:18 ` H Hartley Sweeten
2010-05-18 8:32 ` Oskar Schirmer
2010-05-18 9:37 ` Daniel Glöckner
2010-05-18 8:34 ` [PATCH v2] " Oskar Schirmer
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