* [PATCH] i2c-dev: Clarify the unit of ioctl I2C_TIMEOUT
@ 2009-02-20 12:21 Jean Delvare
[not found] ` <20090220132137.6a86dda6-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
0 siblings, 1 reply; 3+ messages in thread
From: Jean Delvare @ 2009-02-20 12:21 UTC (permalink / raw)
To: Linux I2C; +Cc: Clifford Wolf
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-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
---
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.
+ */
+ 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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] i2c-dev: Clarify the unit of ioctl I2C_TIMEOUT
[not found] ` <20090220132137.6a86dda6-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
@ 2009-02-20 12:28 ` Wolfram Sang
[not found] ` <20090220122839.GA3042-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
0 siblings, 1 reply; 3+ messages in thread
From: Wolfram Sang @ 2009-02-20 12:28 UTC (permalink / raw)
To: Jean Delvare; +Cc: Linux I2C, Clifford Wolf
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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-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
Acked-by: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
(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
> --
> To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Pengutronix e.K. | Wolfram Sang |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] i2c-dev: Clarify the unit of ioctl I2C_TIMEOUT
[not found] ` <20090220122839.GA3042-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
@ 2009-02-20 12:39 ` Jean Delvare
0 siblings, 0 replies; 3+ messages in thread
From: Jean Delvare @ 2009-02-20 12:39 UTC (permalink / raw)
To: Wolfram Sang; +Cc: Linux I2C, Clifford Wolf
On Fri, 20 Feb 2009 13:28:39 +0100, Wolfram Sang wrote:
> 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-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
>
> Acked-by: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Thanks!
>
> (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?
Not intended. Fixed, thanks for reporting!
>
> > + */
> > + 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
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
> > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
>
--
Jean Delvare
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2009-02-20 12:21 [PATCH] i2c-dev: Clarify the unit of ioctl I2C_TIMEOUT Jean Delvare
[not found] ` <20090220132137.6a86dda6-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2009-02-20 12:28 ` Wolfram Sang
[not found] ` <20090220122839.GA3042-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
2009-02-20 12:39 ` Jean Delvare
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