linux-kernel - Re: [RESEND PATCH 3/4] hwmon: (lm85) replace x_TO_REG() functions with find

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Date:	Tue, 24 Feb 2015 13:04:33 -0800
From:	Guenter Roeck <linux@...ck-us.net>
To:	Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Jean Delvare <jdelvare@...e.de>,
	lm-sensors <lm-sensors@...sensors.org>
Subject: Re: [RESEND PATCH 3/4] hwmon: (lm85) replace x_TO_REG() functions
 with find_closest()

On Tue, Feb 24, 2015 at 06:48:28PM +0100, Bartosz Golaszewski wrote:
> Replace RANGE_TO_REG() and FREQ_TO_REG() functions with calls
> to find_closest().
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
> ---
>  drivers/hwmon/lm85.c | 43 ++++++++++++-------------------------------
>  1 file changed, 12 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/hwmon/lm85.c b/drivers/hwmon/lm85.c
> index 2b4b419..4e81c99 100644
> --- a/drivers/hwmon/lm85.c
> +++ b/drivers/hwmon/lm85.c
> @@ -188,18 +188,6 @@ static const int lm85_range_map[] = {
>  	13300, 16000, 20000, 26600, 32000, 40000, 53300, 80000
>  };
>  
> -static int RANGE_TO_REG(long range)
> -{
> -	int i;
> -
> -	/* Find the closest match */
> -	for (i = 0; i < 15; ++i) {
> -		if (range <= (lm85_range_map[i] + lm85_range_map[i + 1]) / 2)
> -			break;
> -	}
> -
> -	return i;
> -}
>  #define RANGE_FROM_REG(val)	lm85_range_map[(val) & 0x0f]
>  
>  /* These are the PWM frequency encodings */
> @@ -209,17 +197,7 @@ static const int lm85_freq_map[8] = { /* 1 Hz */
>  static const int adm1027_freq_map[8] = { /* 1 Hz */
>  	11, 15, 22, 29, 35, 44, 59, 88
>  };
> -
> -static int FREQ_TO_REG(const int *map, unsigned long freq)
> -{
> -	int i;
> -
> -	/* Find the closest match */
> -	for (i = 0; i < 7; ++i)
> -		if (freq <= (map[i] + map[i + 1]) / 2)
> -			break;
> -	return i;
> -}
> +#define FREQ_MAP_SIZE		8

If you declare this as a constant, that constant should also be used
to declare the actual arrays.

>  
>  static int FREQ_FROM_REG(const int *map, u8 reg)
>  {
> @@ -828,7 +806,8 @@ static ssize_t set_pwm_freq(struct device *dev,
>  		data->cfg5 &= ~ADT7468_HFPWM;
>  		lm85_write_value(client, ADT7468_REG_CFG5, data->cfg5);
>  	} else {					/* Low freq. mode */
> -		data->pwm_freq[nr] = FREQ_TO_REG(data->freq_map, val);
> +		data->pwm_freq[nr] = find_closest(val, data->freq_map,
> +						  FREQ_MAP_SIZE - 1);

Why -1 ?

>  		lm85_write_value(client, LM85_REG_AFAN_RANGE(nr),
>  				 (data->zone[nr].range << 4)
>  				 | data->pwm_freq[nr]);
> @@ -1186,7 +1165,7 @@ static ssize_t set_temp_auto_temp_min(struct device *dev,
>  	int nr = to_sensor_dev_attr(attr)->index;
>  	struct lm85_data *data = dev_get_drvdata(dev);
>  	struct i2c_client *client = data->client;
> -	long val;
> +	long val, range;
>  	int err;
>  
>  	err = kstrtol(buf, 10, &val);
> @@ -1198,10 +1177,12 @@ static ssize_t set_temp_auto_temp_min(struct device *dev,
>  	lm85_write_value(client, LM85_REG_AFAN_LIMIT(nr),
>  		data->zone[nr].limit);
>  
> -/* Update temp_auto_max and temp_auto_range */
> -	data->zone[nr].range = RANGE_TO_REG(
> -		TEMP_FROM_REG(data->zone[nr].max_desired) -
> -		TEMP_FROM_REG(data->zone[nr].limit));
> +	/* Update temp_auto_max and temp_auto_range */
> +	range = TEMP_FROM_REG(data->zone[nr].max_desired) -
> +		TEMP_FROM_REG(data->zone[nr].limit);
> +	data->zone[nr].range = find_closest(range, lm85_range_map,
> +					    ARRAY_SIZE(lm85_range_map));
> +

Is that really less complex than before ? Also, I wonder if it creates
more or less code. Can you provide code size comparisons ?

Thanks,
Guenter
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