From: "Oskar Schirmer" <os@emlix.com>
To: Michael Hennerich <Michael.Hennerich@analog.com>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: "Mike Frysinger" <vapier@gentoo.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
"Oskar Schirmer" <os@emlix.com>, "Daniel Glöckner" <dg@emlix.com>,
"Oliver Schneidewind" <osw@emlix.com>,
"Johannes Weiner" <jw@emlix.com>
Subject: [PATCH v3] ad7877: keep dma rx buffers in seperate cache lines
Date: Mon, 10 May 2010 12:42:34 +0200 [thread overview]
Message-ID: <1273488154-2993-1-git-send-email-os@emlix.com> (raw)
In-Reply-To: <1273487642-2169-1-git-send-email-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>
---
drivers/input/touchscreen/ad7877.c | 18 +++++++++++++++---
1 files changed, 15 insertions(+), 3 deletions(-)
v2: add a comment to explain why alignment is needed
v3: fix the typo in comment and layout (- to end of line)
diff --git a/drivers/input/touchscreen/ad7877.c b/drivers/input/touchscreen/ad7877.c
index 885354c..9ebb1b4 100644
--- a/drivers/input/touchscreen/ad7877.c
+++ b/drivers/input/touchscreen/ad7877.c
@@ -153,15 +153,29 @@ enum {
*/
struct ser_req {
+ u16 sample;
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ */
+ char __padalign[L1_CACHE_BYTES - sizeof(u16)];
+
u16 reset;
u16 ref_on;
u16 command;
- u16 sample;
struct spi_message msg;
struct spi_transfer xfer[6];
};
struct ad7877 {
+ u16 conversion_data[AD7877_NR_SENSE];
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ */
+ char __padalign[L1_CACHE_BYTES -
+ AD7877_NR_SENSE * sizeof(u16)];
+
struct input_dev *input;
char phys[32];
@@ -182,8 +196,6 @@ 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;
--
1.5.3.7
WARNING: multiple messages have this Message-ID (diff)
From: "Oskar Schirmer" <os@emlix.com>
To: Michael Hennerich <Michael.Hennerich@analog.com>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: "Mike Frysinger" <vapier@gentoo.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
"Oskar Schirmer" <os@emlix.com>, "Daniel Glöckner" <dg@emlix.com>,
"Oliver Schneidewind" <osw@emlix.com>,
"Johannes Weiner" <jw@emlix.com>
Subject: [PATCH v3] ad7877: keep dma rx buffers in seperate cache lines
Date: Mon, 10 May 2010 12:42:34 +0200 [thread overview]
Message-ID: <1273488154-2993-1-git-send-email-os@emlix.com> (raw)
In-Reply-To: <1273487642-2169-1-git-send-email-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>
---
drivers/input/touchscreen/ad7877.c | 18 +++++++++++++++---
1 files changed, 15 insertions(+), 3 deletions(-)
v2: add a comment to explain why alignment is needed
v3: fix the typo in comment and layout (- to end of line)
diff --git a/drivers/input/touchscreen/ad7877.c b/drivers/input/touchscreen/ad7877.c
index 885354c..9ebb1b4 100644
--- a/drivers/input/touchscreen/ad7877.c
+++ b/drivers/input/touchscreen/ad7877.c
@@ -153,15 +153,29 @@ enum {
*/
struct ser_req {
+ u16 sample;
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ */
+ char __padalign[L1_CACHE_BYTES - sizeof(u16)];
+
u16 reset;
u16 ref_on;
u16 command;
- u16 sample;
struct spi_message msg;
struct spi_transfer xfer[6];
};
struct ad7877 {
+ u16 conversion_data[AD7877_NR_SENSE];
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ */
+ char __padalign[L1_CACHE_BYTES -
+ AD7877_NR_SENSE * sizeof(u16)];
+
struct input_dev *input;
char phys[32];
@@ -182,8 +196,6 @@ 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;
--
1.5.3.7
--
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next prev parent reply other threads:[~2010-05-10 10:42 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 ` Oskar Schirmer [this message]
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
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
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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