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[PATCH] i2c: designware: Enable ioctl I2C_TIMEOUT

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  [PATCH] i2c: designware: Enable ioctl I2C_TIMEOUT Weifeng Voon <weifeng.voon@intel.com> - 2016-06-02 10:00 +0200
    Re: [PATCH] i2c: designware: Enable ioctl I2C_TIMEOUT Uwe Kleine-König   <u.kleine-koenig@pengutronix.de> - 2016-06-02 10:40 +0200
      RE: [PATCH] i2c: designware: Enable ioctl I2C_TIMEOUT "Voon, Weifeng" <weifeng.voon@intel.com> - 2016-06-02 11:20 +0200
        Re: [PATCH] i2c: designware: Enable ioctl I2C_TIMEOUT Wolfram Sang <wsa@the-dreams.de> - 2016-06-09 23:00 +0200

#1411969 — [PATCH] i2c: designware: Enable ioctl I2C_TIMEOUT

This allows applications to set the transfer timeout in 10ms increments via
ioctl I2C_TIMEOUT.

Signed-off-by: Weifeng Voon <weifeng.voon@intel.com>
---
 drivers/i2c/busses/i2c-designware-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 99b54be..c6922b8 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -663,7 +663,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	i2c_dw_xfer_init(dev);
 
 	/* wait for tx to complete */
-	if (!wait_for_completion_timeout(&dev->cmd_complete, HZ)) {
+	if (!wait_for_completion_timeout(&dev->cmd_complete, adap->timeout)) {
 		dev_err(dev->dev, "controller timed out\n");
 		/* i2c_dw_init implicitly disables the adapter */
 		i2c_dw_init(dev);
-- 
1.9.1

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#1411998

On Thu, Jun 02, 2016 at 03:57:30PM +0800, Weifeng Voon wrote:
> This allows applications to set the transfer timeout in 10ms increments via
> ioctl I2C_TIMEOUT.

10ms is only correct with HZ=100. With higher values of HZ you get a
finer resolution. I'd write:

	Respect the transfer timeout set via the I2C_TIMEOUT ioctl.

and not mention the resolution at all. After all your patch doesn't
"enable" that ioctl, just makes use of the value set by it.

Best regards
Uwe


-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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#1412019

> From: Uwe Kleine-König [mailto:u.kleine-koenig@pengutronix.de]
> On Thu, Jun 02, 2016 at 03:57:30PM +0800, Weifeng Voon wrote:
> > This allows applications to set the transfer timeout in 10ms
> > increments via ioctl I2C_TIMEOUT.
> 
> 10ms is only correct with HZ=100. With higher values of HZ you get a finer
> resolution. I'd write:
> 
> 	Respect the transfer timeout set via the I2C_TIMEOUT ioctl.
> 

10ms is correct and regardless of HZ. 
From i2c-dev.c:
client->adapter->timeout = msecs_to_jiffies(arg * 10);

The purpose of putting in the resolution of 10ms is just for the ease of others when
they are using this patch. I am ok to take it out if it is not necessary.

> and not mention the resolution at all. After all your patch doesn't "enable" that
> ioctl, just makes use of the value set by it.

Yes, you are right. I am just using the value set by it. Maybe this may sounds more 
relevant:
	Set transfer timeout via ioctl I2C_TIMEOUT 

Or any other recommendation?

> 
> Best regards
> Uwe
> 
> 
> --
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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#1418641

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> 	Set transfer timeout via ioctl I2C_TIMEOUT 

"Use transfer timeout from ioctl I2C_TIMEOUT"

?

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