Re: [PATCH 2/3]iio:pressure:bmp280: cleanup

[Vlad Dogaru <vlad.dogaru@intel.com>]

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@gmx.de>
> ---
> 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?