linux-kernel - Re: [PATCH] regulator: core: allow non-exact matches in regulator_set_voltage

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Date:	Thu, 22 May 2014 10:34:08 +0200
From:	Lucas Stach <l.stach@...gutronix.de>
To:	Liam Girdwood <lgirdwood@...il.com>
Cc:	Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org,
	kernel@...gutronix.de
Subject: Re: [PATCH] regulator: core: allow non-exact matches in
 regulator_set_voltage_time()

Am Mittwoch, den 21.05.2014, 18:53 +0200 schrieb Lucas Stach:
> Currently this function only provides a valid output if both
> old_uV and new_uV are exact voltages that can be provided by the
> regulator.
> This is almost impossible to achive as the consumer has
> no way to know the exact voltages provided by the regulator.
> Also it creates an unexpected twist in the API, as a user
> could possibly not use the same voltage parameters for
> set_voltage_time() as for set_voltage_time().
And one of the above set_voltage_time() should obviously just have been
a set_voltage().

> 
> This breaks the current cpufreq users of this function, as they
> stick in the raw voltages retrieved from their operating points,
> which may or may not match one of the regulator voltages.
> 
> To make this function behave as expected employ the same logic
> as used when calling set_voltage() and round the voltages to
> the closest matching voltage supported by the regulator.
> 
> Signed-off-by: Lucas Stach <l.stach@...gutronix.de>
> ---
>  drivers/regulator/core.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
> index 9a09f3cdbabb..29ab83f49da9 100644
> --- a/drivers/regulator/core.c
> +++ b/drivers/regulator/core.c
> @@ -2477,7 +2477,7 @@ int regulator_set_voltage_time(struct regulator *regulator,
>  	struct regulator_ops	*ops = rdev->desc->ops;
>  	int old_sel = -1;
>  	int new_sel = -1;
> -	int voltage;
> +	int voltage, best_match_old_uV = INT_MAX, best_match_new_uV = INT_MAX;
>  	int i;
>  
>  	/* Currently requires operations to do this */
> @@ -2486,16 +2486,19 @@ int regulator_set_voltage_time(struct regulator *regulator,
>  		return -EINVAL;
>  
>  	for (i = 0; i < rdev->desc->n_voltages; i++) {
> -		/* We only look for exact voltage matches here */
>  		voltage = regulator_list_voltage(regulator, i);
>  		if (voltage < 0)
>  			return -EINVAL;
>  		if (voltage == 0)
>  			continue;
> -		if (voltage == old_uV)
> +		if (voltage >= old_uV && voltage < best_match_old_uV) {
>  			old_sel = i;
> -		if (voltage == new_uV)
> +			best_match_old_uV = voltage;
> +		}
> +		if (voltage >= new_uV && voltage < best_match_new_uV) {
>  			new_sel = i;
> +			best_match_new_uV = voltage;
> +		}
>  	}
>  
>  	if (old_sel < 0 || new_sel < 0)

-- 
Pengutronix e.K.             | Lucas Stach                 |
Industrial Linux Solutions   | http://www.pengutronix.de/  |

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