[PATCH 2/3] iio: qcom-spmi-iadc: cleanup wait_for_completion return handling

[PATCH 2/3] iio: qcom-spmi-iadc: cleanup wait_for_completion return handling

[Nicholas Mc Guire]

This patch fixes two issues:
* return type of wait_for_completion_timeout is unsigned long not int, 
  rather than adding a dedicated variable the wait_for_completion_timeout
  is moved into the condition directly
* the timeout of wait_for_completion_timeout is in jiffies but the value
  being passed was a unsigned long not converted to jiffies and thus was
  dependent on the HZ settings which is probably not what you want.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
---

Note that the timeout value changed very significantly as wait was 
initially in the range of 2 milliseconds, so this converts to 1 jiffies
for HZ < 1000 and 2 jiffies for HZ=1000 - thus the timeout value changed
by 3 orders of magnitude. This needs a review by someone that knows the
details of the hardware to judge if this change is ok - in any case the
timeout passed should go through usecs_to_jiffies or msecs_to_jiffis and
to ensure it is no longer HZ dependent.

Patch was compile tested only for imx_v6_v7_defconfig + CONFIG_IIO=m
CONFIG_COMPILE_TEST=y, CONFIG_SPMI=m, CONFIG_QCOM_SPMI_IADC=m

Patch is against 3.19.0-rc6 -next-20150130

 drivers/iio/adc/qcom-spmi-iadc.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/qcom-spmi-iadc.c b/drivers/iio/adc/qcom-spmi-iadc.c
index b9666f2..61fb88d 100644
--- a/drivers/iio/adc/qcom-spmi-iadc.c
+++ b/drivers/iio/adc/qcom-spmi-iadc.c
@@ -296,8 +296,8 @@ static int iadc_do_conversion(struct iadc_chip *iadc, int chan, u16 *data)
 	if (iadc->poll_eoc) {
 		ret = iadc_poll_wait_eoc(iadc, wait);
 	} else {
-		ret = wait_for_completion_timeout(&iadc->complete, wait);
-		if (!ret)
+		if (!wait_for_completion_timeout(&iadc->complete, 
+				usecs_to_jiffies(wait)))
 			ret = -ETIMEDOUT;
 		else
 			/* double check conversion status */
-- 
1.7.10.4

Re: [PATCH 2/3] iio: qcom-spmi-iadc: cleanup wait_for_completion return handling

[Jonathan Cameron]

On 02/02/15 08:37, Nicholas Mc Guire wrote:
> This patch fixes two issues:
> * return type of wait_for_completion_timeout is unsigned long not int, 
>   rather than adding a dedicated variable the wait_for_completion_timeout
>   is moved into the condition directly
> * the timeout of wait_for_completion_timeout is in jiffies but the value
>   being passed was a unsigned long not converted to jiffies and thus was
>   dependent on the HZ settings which is probably not what you want.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Ivan, need your Ack / Reviewed-by on this one.

Looks superficially fine to me, but as Nicholas has observed, hardware
knowledge / testing required!

J
> ---
> 
> Note that the timeout value changed very significantly as wait was 
> initially in the range of 2 milliseconds, so this converts to 1 jiffies
> for HZ < 1000 and 2 jiffies for HZ=1000 - thus the timeout value changed
> by 3 orders of magnitude. This needs a review by someone that knows the
> details of the hardware to judge if this change is ok - in any case the
> timeout passed should go through usecs_to_jiffies or msecs_to_jiffis and
> to ensure it is no longer HZ dependent.
> 
> Patch was compile tested only for imx_v6_v7_defconfig + CONFIG_IIO=m
> CONFIG_COMPILE_TEST=y, CONFIG_SPMI=m, CONFIG_QCOM_SPMI_IADC=m
> 
> Patch is against 3.19.0-rc6 -next-20150130
> 
>  drivers/iio/adc/qcom-spmi-iadc.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/qcom-spmi-iadc.c b/drivers/iio/adc/qcom-spmi-iadc.c
> index b9666f2..61fb88d 100644
> --- a/drivers/iio/adc/qcom-spmi-iadc.c
> +++ b/drivers/iio/adc/qcom-spmi-iadc.c
> @@ -296,8 +296,8 @@ static int iadc_do_conversion(struct iadc_chip *iadc, int chan, u16 *data)
>  	if (iadc->poll_eoc) {
>  		ret = iadc_poll_wait_eoc(iadc, wait);
>  	} else {
> -		ret = wait_for_completion_timeout(&iadc->complete, wait);
> -		if (!ret)
> +		if (!wait_for_completion_timeout(&iadc->complete, 
> +				usecs_to_jiffies(wait)))
>  			ret = -ETIMEDOUT;
>  		else
>  			/* double check conversion status */
> 

Re: [PATCH 2/3] iio: qcom-spmi-iadc: cleanup wait_for_completion return handling

[Ivan T. Ivanov]

On Wed, 2015-02-04 at 16:59 +0000, Jonathan Cameron wrote:
> On 02/02/15 08:37, Nicholas Mc Guire wrote:
> > This patch fixes two issues:
> > * return type of wait_for_completion_timeout is unsigned long not int,
> >   rather than adding a dedicated variable the wait_for_completion_timeout
> >   is moved into the condition directly
> > * the timeout of wait_for_completion_timeout is in jiffies but the value
> >   being passed was a unsigned long not converted to jiffies and thus was
> >   dependent on the HZ settings which is probably not what you want.
> > 
> > Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
> Ivan, need your Ack / Reviewed-by on this one.
> 

Yes, change is correct, as explained before [1].

Acked-by: Ivan T. Ivanov <iivanov@mm-sol.com>


[1] https://lkml.org/lkml/2015/1/5/409