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| author | Jean Delvare <khali@linux-fr.org> | 2009-02-24 19:19:49 +0100 |
|---|---|---|
| committer | Jean Delvare <khali@linux-fr.org> | 2009-02-24 19:19:49 +0100 |
| commit | cd97f39b7cdf1c8a9c9f52865eec795b7f0c811d (patch) | |
| tree | 010cd2255376a95120da810a1600bbd8d4d7d1c3 /drivers/i2c | |
| parent | a746b578d8406b2db0e9f0d040061bc1f78433cf (diff) | |
| download | lwn-cd97f39b7cdf1c8a9c9f52865eec795b7f0c811d.tar.gz lwn-cd97f39b7cdf1c8a9c9f52865eec795b7f0c811d.zip | |
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>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/i2c-dev.c | 6 |
1 files changed, 5 insertions, 1 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 |