linux-kernel - Re: [PATCH v4 1/4] iio:temperature:mlx90632: Reduce number of equal calulcations

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Date:   Sat, 8 Aug 2020 22:58:04 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Crt Mori <cmo@...exis.com>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/4] iio:temperature:mlx90632: Reduce number of equal calulcations

On Sat, Aug 8, 2020 at 3:10 PM Crt Mori <cmo@...exis.com> wrote:
>
> TAdut4 was calculated each iteration although it did not change. In light
> of near future additions of the Extended range DSP calculations, this
> function refactoring will help reduce unrelated changes in that series as
> well as reduce the number of new functions needed.

Okay, unifying these two changes (helper function and move the place
where it's called) perhaps good.
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Signed-off-by: Crt Mori <cmo@...exis.com>
> ---
>  drivers/iio/temperature/mlx90632.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/iio/temperature/mlx90632.c b/drivers/iio/temperature/mlx90632.c
> index 51b812bcff2e..c3de10ba5b1e 100644
> --- a/drivers/iio/temperature/mlx90632.c
> +++ b/drivers/iio/temperature/mlx90632.c
> @@ -374,11 +374,11 @@ static s32 mlx90632_calc_temp_ambient(s16 ambient_new_raw, s16 ambient_old_raw,
>  }
>
>  static s32 mlx90632_calc_temp_object_iteration(s32 prev_object_temp, s64 object,
> -                                              s64 TAdut, s32 Fa, s32 Fb,
> +                                              s64 TAdut, s64 TAdut4, s32 Fa, s32 Fb,
>                                                s32 Ga, s16 Ha, s16 Hb,
>                                                u16 emissivity)
>  {
> -       s64 calcedKsTO, calcedKsTA, ir_Alpha, TAdut4, Alpha_corr;
> +       s64 calcedKsTO, calcedKsTA, ir_Alpha, Alpha_corr;
>         s64 Ha_customer, Hb_customer;
>
>         Ha_customer = ((s64)Ha * 1000000LL) >> 14ULL;
> @@ -393,30 +393,35 @@ static s32 mlx90632_calc_temp_object_iteration(s32 prev_object_temp, s64 object,
>         Alpha_corr = emissivity * div64_s64(Alpha_corr, 100000LL);
>         Alpha_corr = div64_s64(Alpha_corr, 1000LL);
>         ir_Alpha = div64_s64((s64)object * 10000000LL, Alpha_corr);
> -       TAdut4 = (div64_s64(TAdut, 10000LL) + 27315) *
> -               (div64_s64(TAdut, 10000LL) + 27315) *
> -               (div64_s64(TAdut, 10000LL)  + 27315) *
> -               (div64_s64(TAdut, 10000LL) + 27315);
>
>         return (int_sqrt64(int_sqrt64(ir_Alpha * 1000000000000LL + TAdut4))
>                 - 27315 - Hb_customer) * 10;
>  }
>
> +static s64 mlx90632_calc_ta4(s64 TAdut, s64 scale)
> +{
> +       return (div64_s64(TAdut, scale) + 27315) *
> +               (div64_s64(TAdut, scale) + 27315) *
> +               (div64_s64(TAdut, scale) + 27315) *
> +               (div64_s64(TAdut, scale) + 27315);
> +}
> +
>  static s32 mlx90632_calc_temp_object(s64 object, s64 ambient, s32 Ea, s32 Eb,
>                                      s32 Fa, s32 Fb, s32 Ga, s16 Ha, s16 Hb,
>                                      u16 tmp_emi)
>  {
> -       s64 kTA, kTA0, TAdut;
> +       s64 kTA, kTA0, TAdut, TAdut4;
>         s64 temp = 25000;
>         s8 i;
>
>         kTA = (Ea * 1000LL) >> 16LL;
>         kTA0 = (Eb * 1000LL) >> 8LL;
>         TAdut = div64_s64(((ambient - kTA0) * 1000000LL), kTA) + 25 * 1000000LL;
> +       TAdut4 = mlx90632_calc_ta4(TAdut, 10000LL);
>
>         /* Iterations of calculation as described in datasheet */
>         for (i = 0; i < 5; ++i) {
> -               temp = mlx90632_calc_temp_object_iteration(temp, object, TAdut,
> +               temp = mlx90632_calc_temp_object_iteration(temp, object, TAdut, TAdut4,
>                                                            Fa, Fb, Ga, Ha, Hb,
>                                                            tmp_emi);
>         }
> --
> 2.25.1
>


-- 
With Best Regards,
Andy Shevchenko