On Fri, Feb 20, 2009 at 01:21:37PM +0100, Jean Delvare wrote:
> The unit in which user-space can set the bus timeout value is jiffies
> for historical reasons (back when HZ was always 100.) This is however
> not good because user-space doesn't know how long a jiffy lasts. The
> timeout value should instead be set in a fixed time unit. Given the
> original value of HZ, this unit should be 10 ms, for compatibility.
>
> Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx>
Acked-by: Wolfram Sang <w.sang@xxxxxxxxxxxxxx>
(see minor nit below)
> ---
> drivers/i2c/i2c-dev.c | 6 +++++-
> include/linux/i2c-dev.h | 2 +-
> include/linux/i2c.h | 2 +-
> 3 files changed, 7 insertions(+), 3 deletions(-)
>
> --- linux-2.6.29-rc5.orig/drivers/i2c/i2c-dev.c 2009-01-06 20:24:44.000000000 +0100
> +++ linux-2.6.29-rc5/drivers/i2c/i2c-dev.c 2009-02-20 12:59:38.000000000 +0100
> @@ -35,6 +35,7 @@
> #include <linux/i2c.h>
> #include <linux/i2c-dev.h>
> #include <linux/smp_lock.h>
> +#include <linux/jiffies.h>
> #include <asm/uaccess.h>
>
> static struct i2c_driver i2cdev_driver;
> @@ -422,7 +423,10 @@ static long i2cdev_ioctl(struct file *fi
> client->adapter->retries = arg;
> break;
> case I2C_TIMEOUT:
> - client->adapter->timeout = arg;
> + /* For historical reasons, user-space sets the timeout
> + * value in units of 10 ms.
Double space after * intended?
> + */
> + client->adapter->timeout = msecs_to_jiffies(arg * 10);
> break;
> default:
> /* NOTE: returning a fault code here could cause trouble
> --- linux-2.6.29-rc5.orig/include/linux/i2c-dev.h 2008-04-17 04:49:44.000000000 +0200
> +++ linux-2.6.29-rc5/include/linux/i2c-dev.h 2009-02-20 12:48:08.000000000 +0100
> @@ -33,7 +33,7 @@
> */
> #define I2C_RETRIES 0x0701 /* number of times a device address should
> be polled when not acknowledging */
> -#define I2C_TIMEOUT 0x0702 /* set timeout in jiffies - call with int */
> +#define I2C_TIMEOUT 0x0702 /* set timeout in units of 10 ms */
>
> /* NOTE: Slave address is 7 or 10 bits, but 10-bit addresses
> * are NOT supported! (due to code brokenness)
> --- linux-2.6.29-rc5.orig/include/linux/i2c.h 2009-01-29 08:27:20.000000000 +0100
> +++ linux-2.6.29-rc5/include/linux/i2c.h 2009-02-20 12:47:39.000000000 +0100
> @@ -361,7 +361,7 @@ struct i2c_adapter {
> struct mutex bus_lock;
> struct mutex clist_lock;
>
> - int timeout;
> + int timeout; /* in jiffies */
> int retries;
> struct device dev; /* the adapter device */
>
>
>
> --
> Jean Delvare
> --
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--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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