Re: [PATCH v3 12/14] regulator: pwm: Retrieve correct voltage

Thierry Reding
2016-07-08T15:43:02Z

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On Tue, Jun 14, 2016 at 11:13:20AM +0200, Boris Brezillon wrote:
> The continuous PWM voltage regulator is caching the voltage value in
> the ->volt_uV field. While most of the time this value should reflect the
> real voltage, sometime it can be sightly different if the PWM device
> rounded the set_duty_cycle request.
> Moreover, this value is not valid until someone has modified the regulator
> output.
>
> Remove the ->volt_uV field and always rely on the PWM state to calculate
> the regulator output.
>
> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> Reviewed-by: Brian Norris <briannorris@chromium.org>
> Tested-by: Brian Norris <briannorris@chromium.org>
> Tested-by: Heiko Stuebner <heiko@sntech.de>
> ---
> Mark,
>
> I know you already added your Tested-by/Acked-by tags on this patch
> but this version has slightly change and is now making use of the
> pwm_get_relative_duty_cycle() helper instead of manually converting
> the absolute duty_cycle value into a relative one.
> ---
> drivers/regulator/pwm-regulator.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c
> index 2000118..80d083f 100644
> --- a/drivers/regulator/pwm-regulator.c
> +++ b/drivers/regulator/pwm-regulator.c
> @@ -35,9 +35,6 @@ struct pwm_regulator_data {
> struct regulator_ops ops;
>
> int state;
> -
> - /* Continuous voltage */
> - int volt_uV;
> };
>
> struct pwm_voltages {
> @@ -135,8 +132,13 @@ static int pwm_regulator_is_enabled(struct regulator_dev *dev)
> static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
> {
> struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
> + int min_uV = rdev->constraints->min_uV;
> + int diff = rdev->constraints->max_uV - min_uV;
> + struct pwm_state pstate;
>
> - return drvdata->volt_uV;
> + pwm_get_state(drvdata->pwm, &pstate);
> +
> + return min_uV + pwm_get_relative_duty_cycle(&pstate, diff);
> }
>
> static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
> @@ -162,8 +164,6 @@ static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
> return ret;
> }
>
> - drvdata->volt_uV = min_uV;
> -
> /* Delay required by PWM regulator to settle to the new voltage */
> usleep_range(ramp_delay, ramp_delay + 1000);
>

This hunk has a minor conflict with the regulator tree and the commit
830583004e61 ("regulator: pwm: Drop unneeded pwm_enable() call") that
it contains.

Mark, do you want me to provide a stable branch with the PWM regulator
patches and resolve that conflict in your tree? Or would you rather take
the whole set based on a stable branch from the PWM tree? Or maybe yet
another possibility would be to base the PWM tree on a stable branch
from the regulator tree containing the above commit.

Or we can let Linus sort out the conflict, it's really quite trivial.

Thierry

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