linux-kernel - Re: [PATCH] iio: adc: ina219: Avoid underflow for sleeping time

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Message-ID: <20170730145059.5975d2fa@kernel.org>
Date:   Sun, 30 Jul 2017 14:50:59 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Stefan Brüns <stefan.bruens@...h-aachen.de>
Cc:     <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>
Subject: Re: [PATCH] iio: adc: ina219: Avoid underflow for sleeping time

On Wed, 26 Jul 2017 23:32:06 +0200
Stefan Brüns <stefan.bruens@...h-aachen.de> 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 <stefan.bruens@...h-aachen.de>
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;
>  
>  	/*