linux-kernel - Re: [PATCH v1 4/7] iio: adc: ina2xx: Do not udelay for several seconds

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Date:   Sun, 17 Dec 2017 11:53:58 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Stefan Brüns <stefan.bruens@...h-aachen.de>
Cc:     <linux-iio@...r.kernel.org>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Maciej Purski <m.purski@...sung.com>,
        <linux-kernel@...r.kernel.org>, "Andrew F . Davis" <afd@...com>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Hartmut Knaack <knaack.h@....de>,
        "Javier Martinez Canillas" <javier@....samsung.com>
Subject: Re: [PATCH v1 4/7] iio: adc: ina2xx: Do not udelay for several
 seconds

On Fri, 8 Dec 2017 18:41:49 +0100
Stefan Brüns <stefan.bruens@...h-aachen.de> wrote:

> The conversion time can be up to 16 seconds (8 ms per channel, 2 channels,
> 1024 times averaging).
> 
> Signed-off-by: Stefan Brüns <stefan.bruens@...h-aachen.de>
Applied
> ---
> 
>  drivers/iio/adc/ina2xx-adc.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
> index b027d485398b..2621a34ee5c6 100644
> --- a/drivers/iio/adc/ina2xx-adc.c
> +++ b/drivers/iio/adc/ina2xx-adc.c
> @@ -764,7 +764,7 @@ static int ina2xx_capture_thread(void *data)
>  	struct iio_dev *indio_dev = data;
>  	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
>  	int sampling_us = SAMPLING_PERIOD(chip);
> -	int buffer_us;
> +	int buffer_us, delay_us;
>  
>  	/*
>  	 * Poll a bit faster than the chip internal Fs, in case
> @@ -778,8 +778,10 @@ static int ina2xx_capture_thread(void *data)
>  		if (buffer_us < 0)
>  			return buffer_us;
>  
> -		if (sampling_us > buffer_us)
> -			udelay(sampling_us - buffer_us);
> +		if (sampling_us > buffer_us) {
> +			delay_us = sampling_us - buffer_us;
> +			usleep_range(delay_us, (delay_us * 3) >> 1);
> +		}
>  
>  	} while (!kthread_should_stop());
>