On Fri, Oct 31, 2014 at 02:23:33AM +0100, Hartmut Knaack wrote:
> The calculations for temperature and pressure compensation were already slightly
> optimized in comparison to the data sheet. So, it makes sense to optimize even a
> bit more, making proper use of C operators:
> - variable t in bmp280_compensate_temp() can be eliminated by directly
> returning the result of the relevant equation.
> - make use of the += operator, eliminate an unnecessary parenthesis level and
> directly return the result of the last equation in
> bmp280_compensate_press().
> When the initialization of the ctrl_meas register fails, the error message will
> now mention the right register name.
> During probe, i2c_set_clientdata() is called, although it is not necessary. Drop
> it.
>
> Signed-off-by: Hartmut Knaack <knaack.h@xxxxxx>
> ---
> diff --git a/drivers/iio/pressure/bmp280.c b/drivers/iio/pressure/bmp280.c
> index 75038da..4f6ae4d 100644
> --- a/drivers/iio/pressure/bmp280.c
> +++ b/drivers/iio/pressure/bmp280.c
> @@ -200,7 +200,7 @@ static s32 bmp280_compensate_temp(struct bmp280_data *data,
> struct bmp280_comp_temp *comp,
> s32 adc_temp)
> {
> - s32 var1, var2, t;
> + s32 var1, var2;
>
> var1 = (((adc_temp >> 3) - ((s32) comp->dig_t1 << 1)) *
> ((s32) comp->dig_t2)) >> 11;
> @@ -209,9 +209,7 @@ static s32 bmp280_compensate_temp(struct bmp280_data *data,
> ((s32) comp->dig_t3)) >> 14;
>
> data->t_fine = var1 + var2;
> - t = (data->t_fine * 5 + 128) >> 8;
> -
> - return t;
> + return (data->t_fine * 5 + 128) >> 8;
Shouldn't the compiler take care of this?
> }
>
> /*
> @@ -229,11 +227,11 @@ static u32 bmp280_compensate_press(struct bmp280_data *data,
>
> var1 = ((s64) data->t_fine) - 128000;
> var2 = var1 * var1 * (s64) comp->dig_p6;
> - var2 = var2 + ((var1 * (s64) comp->dig_p5) << 17);
> - var2 = var2 + (((s64) comp->dig_p4) << 35);
> + var2 += ((var1 * (s64) comp->dig_p5) << 17);
> + var2 += (((s64) comp->dig_p4) << 35);
> var1 = ((var1 * var1 * (s64) comp->dig_p3) >> 8) +
> ((var1 * (s64) comp->dig_p2) << 12);
> - var1 = (((((s64) 1) << 47) + var1)) * ((s64) comp->dig_p1) >> 33;
> + var1 = ((((s64) 1) << 47) + var1) * ((s64) comp->dig_p1) >> 33;
>
> if (var1 == 0)
> return 0;
> @@ -242,9 +240,7 @@ static u32 bmp280_compensate_press(struct bmp280_data *data,
> p = div64_s64(p, var1);
> var1 = (((s64) comp->dig_p9) * (p >> 13) * (p >> 13)) >> 25;
> var2 = (((s64) comp->dig_p8) * p) >> 19;
> - p = ((p + var1 + var2) >> 8) + (((s64) comp->dig_p7) << 4);
> -
> - return (u32) p;
> + return (u32)((p + var1 + var2) >> 8) + (((s64) comp->dig_p7) << 4);
And this?
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