From: Andy Walls <awalls@md.metrocast.net>
To: linux-media@vger.kernel.org
Cc: Mike Isely <isely@isely.net>,
Kenney Phillisjr <kphillisjr@gmail.com>,
Hans Verkuil <hverkuil@xs4all.nl>,
Jean Delvare <khali@linux-fr.org>
Subject: [PATCH 04/17] cx25840: Make cx25840 i2c register read transactions atomic
Date: Mon, 19 Jul 2010 21:11:46 -0400 [thread overview]
Message-ID: <1279588306.28153.6.camel@localhost> (raw)
In-Reply-To: <cover.1279586511.git.awalls@md.metrocast.net>
There was a small window between writing the cx25840 register
address over the i2c bus and reading the register contents back from the
cx25840 device that the i2c adapter lock was released. This change ensures the
adapter lock is not released until the register read is done.
Signed-off-by: Andy Walls <awalls@md.metrocast.net>
---
drivers/media/video/cx25840/cx25840-core.c | 58 +++++++++++++++++++---------
1 files changed, 39 insertions(+), 19 deletions(-)
diff --git a/drivers/media/video/cx25840/cx25840-core.c b/drivers/media/video/cx25840/cx25840-core.c
index bb4872b..4f908fa 100644
--- a/drivers/media/video/cx25840/cx25840-core.c
+++ b/drivers/media/video/cx25840/cx25840-core.c
@@ -80,33 +80,53 @@ int cx25840_write4(struct i2c_client *client, u16 addr, u32 value)
u8 cx25840_read(struct i2c_client * client, u16 addr)
{
- u8 buffer[2];
- buffer[0] = addr >> 8;
- buffer[1] = addr & 0xff;
-
- if (i2c_master_send(client, buffer, 2) < 2)
- return 0;
-
- if (i2c_master_recv(client, buffer, 1) < 1)
+ struct i2c_msg msgs[2];
+ u8 tx_buf[2], rx_buf[1];
+
+ /* Write register address */
+ tx_buf[0] = addr >> 8;
+ tx_buf[1] = addr & 0xff;
+ msgs[0].addr = client->addr;
+ msgs[0].flags = 0;
+ msgs[0].len = 2;
+ msgs[0].buf = (char *) tx_buf;
+
+ /* Read data from register */
+ msgs[1].addr = client->addr;
+ msgs[1].flags = I2C_M_RD;
+ msgs[1].len = 1;
+ msgs[1].buf = (char *) rx_buf;
+
+ if (i2c_transfer(client->adapter, msgs, 2) < 2)
return 0;
- return buffer[0];
+ return rx_buf[0];
}
u32 cx25840_read4(struct i2c_client * client, u16 addr)
{
- u8 buffer[4];
- buffer[0] = addr >> 8;
- buffer[1] = addr & 0xff;
-
- if (i2c_master_send(client, buffer, 2) < 2)
- return 0;
-
- if (i2c_master_recv(client, buffer, 4) < 4)
+ struct i2c_msg msgs[2];
+ u8 tx_buf[2], rx_buf[4];
+
+ /* Write register address */
+ tx_buf[0] = addr >> 8;
+ tx_buf[1] = addr & 0xff;
+ msgs[0].addr = client->addr;
+ msgs[0].flags = 0;
+ msgs[0].len = 2;
+ msgs[0].buf = (char *) tx_buf;
+
+ /* Read data from registers */
+ msgs[1].addr = client->addr;
+ msgs[1].flags = I2C_M_RD;
+ msgs[1].len = 4;
+ msgs[1].buf = (char *) rx_buf;
+
+ if (i2c_transfer(client->adapter, msgs, 2) < 2)
return 0;
- return (buffer[3] << 24) | (buffer[2] << 16) |
- (buffer[1] << 8) | buffer[0];
+ return (rx_buf[3] << 24) | (rx_buf[2] << 16) | (rx_buf[1] << 8) |
+ rx_buf[0];
}
int cx25840_and_or(struct i2c_client *client, u16 addr, unsigned and_mask,
--
1.7.1.1
next prev parent reply other threads:[~2010-07-20 1:16 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1279586511.git.awalls@md.metrocast.net>
2010-07-20 1:08 ` [PATCH 01/17] cx23885: Return -ENXIO on slave nack Andy Walls
2010-07-20 1:09 ` [PATCH 02/17] cx23885: Check for slave nack on all transactions Andy Walls
2010-07-20 1:10 ` [PATCH 03/17] cx23885: i2c_wait_done returns 0 or 1, don't check for < 0 return value Andy Walls
2010-07-20 1:11 ` Andy Walls [this message]
2010-07-20 6:42 ` [PATCH 04/17] cx25840: Make cx25840 i2c register read transactions atomic Jean Delvare
2010-07-20 12:35 ` Andy Walls
2010-07-20 12:46 ` Jean Delvare
2010-07-20 1:12 ` [PATCH 05/17] cx23885: Add correct detection of the HVR-1250 model 79501 Andy Walls
2010-07-20 1:12 ` [PATCH 06/17] cx23885: Add a VIDIOC_LOG_STATUS ioctl function for analog video devices Andy Walls
2010-07-20 1:16 ` [PATCH 07/17] v4l2_subdev: Add s_io_pin_config to v4l2_subdev_core_ops Andy Walls
2010-07-20 1:18 ` [PATCH 08/17] cx25840: Add s_io_pin_config core subdev ops for the CX2388[578] Andy Walls
2010-07-20 1:18 ` [PATCH 09/17] v4l2_subdev, cx23885: Differentiate IR carrier sense and I/O pin inversion Andy Walls
2010-07-20 1:19 ` [PATCH 10/17] cx23885: For CX23888 IR, configure the IO pin mux IR pins explcitly Andy Walls
2010-07-20 1:20 ` [PATCH 11/17] v4l2_subdev: Move interrupt_service_routine ptr to v4l2_subdev_core_ops Andy Walls
2010-07-20 1:22 ` [PATCH 12/17] cx25840: Add support for CX2388[57] A/V core integrated IR controllers Andy Walls
2010-07-20 1:22 ` [PATCH 13/17] cx23885: Add a v4l2_subdev group id for the CX2388[578] integrated AV core Andy Walls
2010-07-20 1:23 ` [PATCH 14/17] cx23885: Add preliminary IR Rx support for the HVR-1250 and TeVii S470 Andy Walls
2010-07-20 1:25 ` [PATCH 15/17] cx23885: Protect PCI interrupt mask manipulations with a spinlock Andy Walls
2010-07-20 1:25 ` [PATCH 16/17] cx23885: Move AV Core irq handling to a work handler Andy Walls
2010-07-20 1:26 ` [PATCH 17/17] cx23885: Require user to explicitly enable CX2388[57] IR via module param Andy Walls
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