Re: [PATCH 1/3] i2c/algo-pca: rework waiting for a free bus

[Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>]

Hi Wolfram,

On Tue, 24 Feb 2009 17:22:14 +0100, Wolfram Sang wrote:
> Waiting for a free bus now accepts the timeout value in jiffies and does
> proper checking using time_before.
> 
> Signed-off-by: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> ---
>  drivers/i2c/algos/i2c-algo-pca.c |   18 ++++++++++--------
>  drivers/i2c/busses/i2c-pca-isa.c |    2 +-
>  include/linux/i2c-pca-platform.h |    2 +-
>  3 files changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/i2c/algos/i2c-algo-pca.c b/drivers/i2c/algos/i2c-algo-pca.c
> index a8e51bd..59ee88a 100644
> --- a/drivers/i2c/algos/i2c-algo-pca.c
> +++ b/drivers/i2c/algos/i2c-algo-pca.c
> @@ -22,6 +22,7 @@
>  #include <linux/module.h>
>  #include <linux/moduleparam.h>
>  #include <linux/delay.h>
> +#include <linux/jiffies.h>
>  #include <linux/init.h>
>  #include <linux/errno.h>
>  #include <linux/i2c.h>
> @@ -186,14 +187,15 @@ static int pca_xfer(struct i2c_adapter *i2c_adap,
>  	int numbytes = 0;
>  	int state;
>  	int ret;
> -	int timeout = i2c_adap->timeout;
> +	unsigned long timeout = jiffies + i2c_adap->timeout;
>  
> -	while ((state = pca_status(adap)) != 0xf8 && timeout--) {
> -		msleep(10);
> -	}
> -	if (state != 0xf8) {
> -		dev_dbg(&i2c_adap->dev, "bus is not idle. status is %#04x\n", state);
> -		return -EAGAIN;
> +	while (pca_status(adap) != 0xf8) {
> +		if (time_before(jiffies, timeout)) {
> +			msleep(10);
> +		} else {
> +			dev_dbg(&i2c_adap->dev, "bus is not idle. status is %#04x\n", state);

Line too long, needs folding.

> +			return -EAGAIN;
> +		}
>  	}
>  
>  	DEB1("{{{ XFER %d messages\n", num);
> diff --git a/drivers/i2c/busses/i2c-pca-isa.c b/drivers/i2c/busses/i2c-pca-isa.c
> index 8835de2..84d035c 100644
> --- a/drivers/i2c/busses/i2c-pca-isa.c
> +++ b/drivers/i2c/busses/i2c-pca-isa.c
> @@ -103,7 +103,7 @@ static struct i2c_adapter pca_isa_ops = {
>  	.owner          = THIS_MODULE,
>  	.algo_data	= &pca_isa_data,
>  	.name		= "PCA9564/PCA9665 ISA Adapter",
> -	.timeout	= 100,
> +	.timeout	= HZ,
>  };
>  
>  static int __devinit pca_isa_match(struct device *dev, unsigned int id)
> diff --git a/include/linux/i2c-pca-platform.h b/include/linux/i2c-pca-platform.h
> index 3d19187..aba3375 100644
> --- a/include/linux/i2c-pca-platform.h
> +++ b/include/linux/i2c-pca-platform.h
> @@ -6,7 +6,7 @@ struct i2c_pca9564_pf_platform_data {
>  				 * not supplied (negative value), but it
>  				 * cannot exit some error conditions then */
>  	int i2c_clock_speed;	/* values are defined in linux/i2c-algo-pca.h */
> -	int timeout;		/* timeout = this value * 10us */
> +	int timeout;		/* timeout in jiffies */

As you change the unit here, you need to update all instances of this
structure in the kernel tree. Which as far as I can see is really only
one in arch/sh/boards/board-sh7785lcr.c.

>  };
>  
>  #endif /* I2C_PCA9564_PLATFORM_H */


-- 
Jean Delvare