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| author | Jean Delvare <khali@linux-fr.org> | 2009-02-24 21:19:49 +0300 |
|---|---|---|
| committer | Jean Delvare <khali@linux-fr.org> | 2009-02-24 21:19:49 +0300 |
| commit | cd97f39b7cdf1c8a9c9f52865eec795b7f0c811d (patch) | |
| tree | 010cd2255376a95120da810a1600bbd8d4d7d1c3 | |
| parent | a746b578d8406b2db0e9f0d040061bc1f78433cf (diff) | |
| download | linux-cd97f39b7cdf1c8a9c9f52865eec795b7f0c811d.tar.xz | |
i2c-dev: Clarify the unit of ioctl I2C_TIMEOUT
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@linux-fr.org>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
| -rw-r--r-- | drivers/i2c/i2c-dev.c | 6 | ||||
| -rw-r--r-- | include/linux/i2c-dev.h | 2 | ||||
| -rw-r--r-- | include/linux/i2c.h | 2 |
3 files changed, 7 insertions, 3 deletions
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c index c171988a9f51..7e13d2df9af3 100644 --- a/drivers/i2c/i2c-dev.c +++ b/drivers/i2c/i2c-dev.c @@ -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 *file, unsigned int cmd, unsigned long arg) 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. + */ + client->adapter->timeout = msecs_to_jiffies(arg * 10); break; default: /* NOTE: returning a fault code here could cause trouble diff --git a/include/linux/i2c-dev.h b/include/linux/i2c-dev.h index 311315b56b61..fd53bfd26470 100644 --- a/include/linux/i2c-dev.h +++ b/include/linux/i2c-dev.h @@ -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) diff --git a/include/linux/i2c.h b/include/linux/i2c.h index fcfbfea3af72..c86c3b07604c 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -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 */ |