2017-07-26 21:32:26

by Stefan Brüns

Subject: [PATCH] iio: adc: ina219: Avoid underflow for sleeping time

Proper support for the INA219 lowered the minimum sampling period from
2*140us to 2*84us. Subtracting 200us later leads to an underflow and
an almost infinite udelay later.

Using a signed int for the sampling period provides sufficient range
(at most 2*8640*1024us), but catches the underflow when comparing with
buffer_us.

Fixes: 18edac2e22f4 ("iio: adc: Fix integration time/averaging for INA219/220")
Signed-off-by: Stefan Brüns <[email protected]>
---
drivers/iio/adc/ina2xx-adc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index b0d9e3b80e6d..85b419ea9ba9 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -657,7 +657,7 @@ static int ina2xx_capture_thread(void *data)
{
struct iio_dev *indio_dev = data;
struct ina2xx_chip_info *chip = iio_priv(indio_dev);
- unsigned int sampling_us = SAMPLING_PERIOD(chip);
+ int sampling_us = SAMPLING_PERIOD(chip);
int buffer_us;

/*
--
2.13.3

2017-07-30 13:51:05

by Jonathan Cameron

Subject: Re: [PATCH] iio: adc: ina219: Avoid underflow for sleeping time

On Wed, 26 Jul 2017 23:32:06 +0200
Stefan Brüns <[email protected]> wrote:

> Proper support for the INA219 lowered the minimum sampling period from
> 2*140us to 2*84us. Subtracting 200us later leads to an underflow and
> an almost infinite udelay later.
>
> Using a signed int for the sampling period provides sufficient range
> (at most 2*8640*1024us), but catches the underflow when comparing with
> buffer_us.
>
> Fixes: 18edac2e22f4 ("iio: adc: Fix integration time/averaging for INA219/220")
> Signed-off-by: Stefan Brüns <[email protected]>
applied to the fixes-togreg branch of iio.git

Thanks,

Jonathan
> ---
> drivers/iio/adc/ina2xx-adc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
> index b0d9e3b80e6d..85b419ea9ba9 100644
> --- a/drivers/iio/adc/ina2xx-adc.c
> +++ b/drivers/iio/adc/ina2xx-adc.c
> @@ -657,7 +657,7 @@ static int ina2xx_capture_thread(void *data)
> {
> struct iio_dev *indio_dev = data;
> struct ina2xx_chip_info *chip = iio_priv(indio_dev);
> - unsigned int sampling_us = SAMPLING_PERIOD(chip);
> + int sampling_us = SAMPLING_PERIOD(chip);
> int buffer_us;
>
> /*