linux-kernel - Re: [PATCH 3/4] extcon: arizona: Update manual headphone detection calculation

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Date:	Fri, 30 May 2014 10:27:35 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
Cc:	myungjoo.ham@...sung.com, patches@...nsource.wolfsonmicro.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] extcon: arizona: Update manual headphone detection
 calculation

Hi Charles,

On 05/30/2014 12:27 AM, Charles Keepax wrote:
> The higher levels of impedance have a higher minimum value than the
> first level. As the same value was used for all levels, higher impedances
> were reported with a very low level of accuracy. This patch applies the
> approriate lower threshold for each level.
> 
> Signed-off-by: Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
> ---
>  drivers/extcon/extcon-arizona.c |   13 ++++++++-----
>  1 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/extcon/extcon-arizona.c b/drivers/extcon/extcon-arizona.c
> index f2c36b1..c1c8647 100644
> --- a/drivers/extcon/extcon-arizona.c
> +++ b/drivers/extcon/extcon-arizona.c
> @@ -329,12 +329,13 @@ static void arizona_stop_mic(struct arizona_extcon_info *info)
>  }
>  
>  static struct {
> +	unsigned int threshold;
>  	unsigned int factor_a;
>  	unsigned int factor_b;
>  } arizona_hpdet_b_ranges[] = {
> -	{  5528,   362464 },
> -	{ 11084,  6186851 },
> -	{ 11065, 65460395 },
> +	{ 100,  5528,   362464 },
> +	{ 169, 11084,  6186851 },
> +	{ 169, 11065, 65460395 },

If you possible, I want to know the 'unit' of the variable(factor_a, factor_b).

>  };
>  
>  static struct {
> @@ -391,7 +392,8 @@ static int arizona_hpdet_read(struct arizona_extcon_info *info)
>  			   >> ARIZONA_HP_IMPEDANCE_RANGE_SHIFT;
>  
>  		if (range < ARRAY_SIZE(arizona_hpdet_b_ranges) - 1 &&
> -		    (val < 100 || val >= 0x3fb)) {
> +		    (val < arizona_hpdet_b_ranges[range].threshold ||
> +		     val >= 0x3fb)) {

I don't understand the meaning of 0x3fb hex value.
I prefer to define constant variable for readability.

>  			range++;
>  			dev_dbg(arizona->dev, "Moving to HPDET range %d\n",
>  				range);
> @@ -404,7 +406,8 @@ static int arizona_hpdet_read(struct arizona_extcon_info *info)
>  		}
>  
>  		/* If we go out of range report top of range */
> -		if (val < 100 || val >= 0x3fb) {
> +		if (val < arizona_hpdet_b_ranges[range].threshold ||
> +		    val >= 0x3fb) {

ditto.

>  			dev_dbg(arizona->dev, "Measurement out of range\n");
>  			return ARIZONA_HPDET_MAX;
>  		}
> 

Thanks,
Chanwoo Choi

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