From: "Oskar Schirmer" <os@emlix.com> To: Dmitry Torokhov <dmitry.torokhov@gmail.com> Cc: "Andrew Morton" <akpm@linux-foundation.org>, "Oskar Schirmer" <os@emlix.com>, "Michael Hennerich" <Michael.Hennerich@analog.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: Tue, 11 May 2010 16:12:11 +0200 [thread overview] Message-ID: <20100511141210.GA28765@emlix.com> (raw) In-Reply-To: <20100511060547.GA9644@core.coreip.homeip.net> On Mon, May 10, 2010 at 23:05:47 -0700, Dmitry Torokhov wrote: > OK, then I have the following which I will apply unless someone shouts. Looks good, we tested it on G45, works fine. Oskar > -- > Dmitry > > Input: ad7877 - keep dma rx buffers in seperate cache lines > > From: Oskar Schirmer <os@emlix.com> > > 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. > > Signed-off-by: Oskar Schirmer <os@emlix.com> > Signed-off-by: Daniel Glöckner <dg@emlix.com> > Signed-off-by: Oliver Schneidewind <osw@emlix.com> > Signed-off-by: Johannes Weiner <jw@emlix.com> > Acked-by: Mike Frysinger <vapier@gentoo.org> > [dtor@mail.ru - changed to use ___cacheline_aligned at suggestion > of akpm] > Signed-off-by: Dmitry Torokhov <dtor@mail.ru> > --- > > drivers/input/touchscreen/ad7877.c | 15 ++++++++++++--- > 1 files changed, 12 insertions(+), 3 deletions(-) > > > diff --git a/drivers/input/touchscreen/ad7877.c b/drivers/input/touchscreen/ad7877.c > index e019d53..0d2d7e5 100644 > --- a/drivers/input/touchscreen/ad7877.c > +++ b/drivers/input/touchscreen/ad7877.c > @@ -156,9 +156,14 @@ struct ser_req { > u16 reset; > u16 ref_on; > u16 command; > - u16 sample; > struct spi_message msg; > struct spi_transfer xfer[6]; > + > + /* > + * DMA (thus cache coherency maintenance) requires the > + * transfer buffers to live in their own cache lines. > + */ > + u16 sample ____cacheline_aligned; > }; > > struct ad7877 { > @@ -182,8 +187,6 @@ struct ad7877 { > u8 averaging; > u8 pen_down_acc_interval; > > - u16 conversion_data[AD7877_NR_SENSE]; > - > struct spi_transfer xfer[AD7877_NR_SENSE + 2]; > struct spi_message msg; > > @@ -195,6 +198,12 @@ struct ad7877 { > spinlock_t lock; > struct timer_list timer; /* P: lock */ > unsigned pending:1; /* P: lock */ > + > + /* > + * DMA (thus cache coherency maintenance) requires the > + * transfer buffers to live in their own cache lines. > + */ > + u16 conversion_data[AD7877_NR_SENSE] ____cacheline_aligned; > }; > > static int gpio3; > > -- oskar schirmer, emlix gmbh, http://www.emlix.com fon +49 551 30664-0, fax -11, bahnhofsallee 1b, 37081 göttingen, germany sitz der gesellschaft: göttingen, amtsgericht göttingen hr b 3160 geschäftsführer: dr. uwe kracke, ust-idnr.: de 205 198 055 emlix - your embedded linux partner
WARNING: multiple messages have this Message-ID (diff)
From: "Oskar Schirmer" <os@emlix.com> To: Dmitry Torokhov <dmitry.torokhov@gmail.com> Cc: "Andrew Morton" <akpm@linux-foundation.org>, "Oskar Schirmer" <os@emlix.com>, "Michael Hennerich" <Michael.Hennerich@analog.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: Tue, 11 May 2010 16:12:11 +0200 [thread overview] Message-ID: <20100511141210.GA28765@emlix.com> (raw) In-Reply-To: <20100511060547.GA9644@core.coreip.homeip.net> On Mon, May 10, 2010 at 23:05:47 -0700, Dmitry Torokhov wrote: > OK, then I have the following which I will apply unless someone shouts. Looks good, we tested it on G45, works fine. Oskar > -- > Dmitry > > Input: ad7877 - keep dma rx buffers in seperate cache lines > > From: Oskar Schirmer <os@emlix.com> > > 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. > > Signed-off-by: Oskar Schirmer <os@emlix.com> > Signed-off-by: Daniel Glöckner <dg@emlix.com> > Signed-off-by: Oliver Schneidewind <osw@emlix.com> > Signed-off-by: Johannes Weiner <jw@emlix.com> > Acked-by: Mike Frysinger <vapier@gentoo.org> > [dtor@mail.ru - changed to use ___cacheline_aligned at suggestion > of akpm] > Signed-off-by: Dmitry Torokhov <dtor@mail.ru> > --- > > drivers/input/touchscreen/ad7877.c | 15 ++++++++++++--- > 1 files changed, 12 insertions(+), 3 deletions(-) > > > diff --git a/drivers/input/touchscreen/ad7877.c b/drivers/input/touchscreen/ad7877.c > index e019d53..0d2d7e5 100644 > --- a/drivers/input/touchscreen/ad7877.c > +++ b/drivers/input/touchscreen/ad7877.c > @@ -156,9 +156,14 @@ struct ser_req { > u16 reset; > u16 ref_on; > u16 command; > - u16 sample; > struct spi_message msg; > struct spi_transfer xfer[6]; > + > + /* > + * DMA (thus cache coherency maintenance) requires the > + * transfer buffers to live in their own cache lines. > + */ > + u16 sample ____cacheline_aligned; > }; > > struct ad7877 { > @@ -182,8 +187,6 @@ struct ad7877 { > u8 averaging; > u8 pen_down_acc_interval; > > - u16 conversion_data[AD7877_NR_SENSE]; > - > struct spi_transfer xfer[AD7877_NR_SENSE + 2]; > struct spi_message msg; > > @@ -195,6 +198,12 @@ struct ad7877 { > spinlock_t lock; > struct timer_list timer; /* P: lock */ > unsigned pending:1; /* P: lock */ > + > + /* > + * DMA (thus cache coherency maintenance) requires the > + * transfer buffers to live in their own cache lines. > + */ > + u16 conversion_data[AD7877_NR_SENSE] ____cacheline_aligned; > }; > > static int gpio3; > > -- oskar schirmer, emlix gmbh, http://www.emlix.com fon +49 551 30664-0, fax -11, bahnhofsallee 1b, 37081 göttingen, germany sitz der gesellschaft: göttingen, amtsgericht göttingen hr b 3160 geschäftsführer: dr. uwe kracke, ust-idnr.: de 205 198 055 emlix - your embedded linux partner -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2010-05-11 14:12 UTC|newest] Thread overview: 124+ 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 ` 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 2010-05-06 18:46 ` Mike Frysinger 2010-05-07 10:15 ` Oskar Schirmer 2010-05-07 10:15 ` Oskar Schirmer 2010-05-07 18:28 ` Mike Frysinger 2010-05-07 18:28 ` Mike Frysinger 2010-05-08 22:32 ` Johannes Weiner 2010-05-08 22:32 ` Johannes Weiner 2010-05-09 4:45 ` Mike Frysinger 2010-05-09 4:45 ` Mike Frysinger 2010-05-09 8:50 ` Oskar Schirmer 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 10:34 ` Oskar Schirmer 2010-05-10 10:42 ` [PATCH v3] " Oskar Schirmer 2010-05-10 10:42 ` 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 2010-05-11 6:05 ` Dmitry Torokhov 2010-05-11 6:05 ` Dmitry Torokhov 2010-05-11 6:11 ` Mike Frysinger 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 6:23 ` Mike Frysinger 2010-05-11 6:33 ` Dmitry Torokhov 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 20:10 ` 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 20:43 ` 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 20:54 ` Mike Frysinger 2010-05-11 21:01 ` Pekka Enberg 2010-05-11 21:11 ` Mike Frysinger 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 2010-05-11 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 4:35 ` Mike Frysinger 2010-05-12 5:28 ` FUJITA Tomonori 2010-05-12 5:28 ` FUJITA Tomonori 2010-05-12 14:37 ` Mike Frysinger 2010-05-12 14:37 ` Mike Frysinger 2010-05-12 18:11 ` Dmitry Torokhov 2010-05-12 18:28 ` Mike Frysinger 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 2010-05-12 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 [this message] 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 11:18 ` Hennerich, Michael 2010-05-06 18:26 ` Mike Frysinger 2010-05-06 18:26 ` Mike Frysinger 2010-05-07 9:41 ` Daniel Glöckner 2010-05-07 9:41 ` Daniel Glöckner 2010-05-07 18:23 ` Mike Frysinger 2010-05-07 18:23 ` Mike Frysinger 2010-05-13 7:53 ` Dmitry Torokhov 2010-05-13 7:53 ` Dmitry Torokhov 2010-05-15 18:15 ` Oskar Schirmer 2010-05-15 18:15 ` Oskar Schirmer 2010-05-16 19:25 ` Mike Frysinger 2010-05-16 19:25 ` Mike Frysinger 2010-05-17 7:29 ` Oskar Schirmer 2010-05-17 7:29 ` Oskar Schirmer 2010-05-17 8:14 ` Hennerich, Michael 2010-05-17 8:14 ` Hennerich, Michael 2010-05-17 8:41 ` Oskar Schirmer 2010-05-17 8:41 ` Oskar Schirmer 2010-05-17 23:49 ` Mike Frysinger 2010-05-17 23:49 ` Mike Frysinger 2010-05-18 0:18 ` H Hartley Sweeten 2010-05-18 0:18 ` H Hartley Sweeten 2010-05-18 8:32 ` Oskar Schirmer 2010-05-18 8:32 ` Oskar Schirmer 2010-05-18 9:37 ` Daniel Glöckner 2010-05-18 9:37 ` Daniel Glöckner 2010-05-18 8:34 ` [PATCH v2] " Oskar Schirmer 2010-05-18 8:34 ` Oskar Schirmer
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