linux-kernel - Re: [PATCH] drivers: iio: proximity: This patch fix the following checkpatch warning.

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Message-ID: <CAJCx=gmi6=uXbydpE2gY2x-XijtAd=bfufoJ+gbO1KU1n++g3Q@mail.gmail.com>
Date:   Thu, 18 Apr 2019 16:23:51 -0700
From:   Matt Ranostay <matt.ranostay@...sulko.com>
To:     Mohan Kumar <mohankumar718@...il.com>
Cc:     Andreas Klinger <ak@...klinger.de>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers: iio: proximity: This patch fix the following
 checkpatch warning.

See comments inline

On Wed, Apr 17, 2019 at 11:15 AM Mohan Kumar <mohankumar718@...il.com> wrote:
>
> As per Documentation/timers/timers-howto.txt Msleep < 20ms can sleep for
> up to 20ms. so use usleep_range.
>
> Signed-off-by: Mohan Kumar <mohankumar718@...il.com>
> ---
>  drivers/iio/proximity/mb1232.c | 2 +-
>  drivers/iio/proximity/srf08.c  | 4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iio/proximity/mb1232.c b/drivers/iio/proximity/mb1232.c
> index 166b3e6..74f7eae 100644
> --- a/drivers/iio/proximity/mb1232.c
> +++ b/drivers/iio/proximity/mb1232.c
> @@ -81,7 +81,7 @@ static s16 mb1232_read_distance(struct mb1232_data *data)
>                 }
>         } else {
>                 /* use simple sleep if announce irq is not connected */
> -               msleep(15);
> +               usleep_range(15000, 20000);

This is actually less than ideal.. because usleep_range uses the
hrtimers which forces an interrupt.

Unless you actually need to read between 15ms and 20ms it is best just
to leave the msleep() as it is, and let it take a bit longer
if required.

- Matt

>         }
>
>         ret = i2c_master_recv(client, (char *)&buf, sizeof(buf));
> diff --git a/drivers/iio/proximity/srf08.c b/drivers/iio/proximity/srf08.c
> index f2bf783..605a582 100644
> --- a/drivers/iio/proximity/srf08.c
> +++ b/drivers/iio/proximity/srf08.c
> @@ -150,7 +150,7 @@ static int srf08_read_ranging(struct srf08_data *data)
>          * polling for not more than 20 ms should be enough
>          */
>         waittime = 1 + data->range_mm / 172;
> -       msleep(waittime);
> +       usleep_range(waittime * 1000, (waittime * 1000) + 2000);
>         for (i = 0; i < 4; i++) {
>                 ret = i2c_smbus_read_byte_data(data->client,
>                                                 SRF08_READ_SW_REVISION);
> @@ -158,7 +158,7 @@ static int srf08_read_ranging(struct srf08_data *data)
>                 /* check if a valid version number is read */
>                 if (ret < 255 && ret > 0)
>                         break;
> -               msleep(5);
> +               usleep_range(5000, 15000);
>         }
>
>         if (ret >= 255 || ret <= 0) {
> --
> 2.7.4
>