linux-kernel - Re: [PATCH 2/3] docs: hwmon: (ltc2945): change type of val to ULL in ltc2945_val_to

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Date:   Mon, 9 Nov 2020 08:38:57 +0200
From:   Alexandru Ardelean <ardeleanalex@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Alexandru Ardelean <alexandru.ardelean@...log.com>,
        linux-hwmon@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        jdelvare@...e.com, Mark.Thoren@...log.com
Subject: Re: [PATCH 2/3] docs: hwmon: (ltc2945): change type of val to ULL in ltc2945_val_to_reg()

On Fri, Nov 6, 2020 at 3:14 PM Guenter Roeck <linux@...ck-us.net> wrote:
>
> On Fri, Nov 06, 2020 at 12:18:24PM +0200, Alexandru Ardelean wrote:
> > In order to account for any potential overflows that could occur.
> >
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
> > ---
> >  drivers/hwmon/ltc2945.c | 14 +++++++-------
> >  1 file changed, 7 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
> > index 1cea710df668..75d997d31e01 100644
> > --- a/drivers/hwmon/ltc2945.c
> > +++ b/drivers/hwmon/ltc2945.c
> > @@ -155,7 +155,7 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
> >  }
> >
> >  static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> > -                           unsigned long val)
> > +                           unsigned long long val)
> >  {
> >       struct ltc2945_state *st = dev_get_drvdata(dev);
> >       struct regmap *regmap = st->regmap;
> > @@ -181,14 +181,14 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> >                       return ret;
> >               if (control & CONTROL_MULT_SELECT) {
> >                       /* 25 mV * 25 uV = 0.625 uV resolution. */
> > -                     val = DIV_ROUND_CLOSEST(val, 625);
> > +                     val = DIV_ROUND_CLOSEST_ULL(val, 625);
> >               } else {
> >                       /*
> >                        * 0.5 mV * 25 uV = 0.0125 uV resolution.
> >                        * Divide first to avoid overflow;
> >                        * accept loss of accuracy.
> >                        */
> > -                     val = DIV_ROUND_CLOSEST(val, 25) * 2;
> > +                     val = DIV_ROUND_CLOSEST_ULL(val, 25) * 2;
> >               }
> >               break;
> >       case LTC2945_VIN_H:
> > @@ -197,7 +197,7 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> >       case LTC2945_MAX_VIN_THRES_H:
> >       case LTC2945_MIN_VIN_THRES_H:
> >               /* 25 mV resolution. */
> > -             val /= 25;
> > +             val = div_u64(val, 25);
> >               break;
> >       case LTC2945_ADIN_H:
> >       case LTC2945_MAX_ADIN_H:
> > @@ -219,7 +219,7 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
> >                * dividing the reported current by the sense resistor value
> >                * in mOhm.
> >                */
> > -             val = DIV_ROUND_CLOSEST(val, 25);
> > +             val = DIV_ROUND_CLOSEST_ULL(val, 25);
> >               break;
> >       default:
> >               return -EINVAL;
> > @@ -247,13 +247,13 @@ static ssize_t ltc2945_value_store(struct device *dev,
> >       struct ltc2945_state *st = dev_get_drvdata(dev);
> >       struct regmap *regmap = st->regmap;
> >       u8 reg = attr->index;
> > -     unsigned long val;
> > +     unsigned long long val;
> >       u8 regbuf[3];
> >       int num_regs;
> >       int regval;
> >       int ret;
> >
> > -     ret = kstrtoul(buf, 10, &val);
> > +     ret = kstrtoull(buf, 10, &val);
>
> This part of the change is unnecessary. Just keep 'val' as-is.
> ltc2945_val_to_reg() can still accept ull.

Ack

>
> Guenter
>
> >       if (ret)
> >               return ret;
> >
> > --
> > 2.27.0
> >