Re: [PATCH 10/14] regulator: pwm: Switch to the atomic PWM API

Brian Norris
2016-06-03T20:50:28Z

+ Laxman

Hi,

On Fri, Jun 03, 2016 at 10:23:08AM +0200, Boris Brezillon wrote:
> Use the atomic API wherever appropriate and get rid of pwm_apply_args()
> call (the reference period and polarity are now explicitly set when
> calling pwm_apply_state()).
>
> We also make use of the pwm_set_relative_duty_cycle() helper to ease
> relative to absolute duty_cycle conversion.
>
> Signed-off-by: Boris Brezillon <boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> ---
> drivers/regulator/pwm-regulator.c | 38 ++++++++++----------------------------
> 1 file changed, 10 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/regulator/pwm-regulator.c b/drivers/regulator/pwm-regulator.c
> index 524b43f..bf033fd 100644
> --- a/drivers/regulator/pwm-regulator.c
> +++ b/drivers/regulator/pwm-regulator.c
> @@ -59,16 +59,14 @@ static int pwm_regulator_set_voltage_sel(struct regulator_dev *rdev,
> unsigned selector)
> {
> struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
> - struct pwm_args pargs;
> - int dutycycle;
> + struct pwm_state pstate;
> int ret;
>
> - pwm_get_args(drvdata->pwm, &pargs);
> + pwm_prepare_new_state(drvdata->pwm, &pstate);
> + pwm_set_relative_duty_cycle(&pstate,
> + drvdata->duty_cycle_table[selector].dutycycle, 100);
>
> - dutycycle = (pargs.period *
> - drvdata->duty_cycle_table[selector].dutycycle) / 100;
> -
> - ret = pwm_config(drvdata->pwm, dutycycle, pargs.period);
> + ret = pwm_apply_state(drvdata->pwm, &pstate);
> if (ret) {
> dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret);
> return ret;
> @@ -126,34 +124,18 @@ static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
> {
> struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
> unsigned int ramp_delay = rdev->constraints->ramp_delay;
> - struct pwm_args pargs;
> unsigned int req_diff = min_uV - rdev->constraints->min_uV;
> + struct pwm_state pstate;
> unsigned int diff;
> - unsigned int duty_pulse;
> - u64 req_period;
> - u32 rem;
> int ret;
>
> - pwm_get_args(drvdata->pwm, &pargs);
> + pwm_prepare_new_state(drvdata->pwm, &pstate);
> diff = rdev->constraints->max_uV - rdev->constraints->min_uV;
>
> - /* First try to find out if we get the iduty cycle time which is
> - * factor of PWM period time. If (request_diff_to_min * pwm_period)
> - * is perfect divided by voltage_range_diff then it is possible to
> - * get duty cycle time which is factor of PWM period. This will help
> - * to get output voltage nearer to requested value as there is no
> - * calculation loss.
> - */
> - req_period = req_diff * pargs.period;
> - div_u64_rem(req_period, diff, &rem);
> - if (!rem) {
> - do_div(req_period, diff);
> - duty_pulse = (unsigned int)req_period;
> - } else {
> - duty_pulse = (pargs.period / 100) * ((req_diff * 100) / diff);
> - }
> + /* We pass diff as the scale to get a uV precision. */
> + pwm_set_relative_duty_cycle(&pstate, req_diff, diff);

Notably, you're dropping much of Laxman's commit fd786fb0276a ("regulator:
pwm: Try to avoid voltage error in duty cycle calculation"), but I
believe the DIV_ROUND_CLOSEST_ULL() in pwm_set_relative_duty_cycle()
solves his problem better.

>
> - ret = pwm_config(drvdata->pwm, duty_pulse, pargs.period);
> + ret = pwm_apply_state(drvdata->pwm, &pstate);
> if (ret) {
> dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret);
> return ret;

Reviewed-by: Brian Norris <briannorris-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Tested-by: Brian Norris <briannorris-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
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