Re: [PATCH] staging: greybus: introduce pwm_ops::apply

[Song Chen]

在 2022/2/10 18:03, Uwe Kleine-König 写道:
> On Thu, Feb 10, 2022 at 05:05:02PM +0800, Song Chen wrote:
> > Introduce apply in pwm_ops to replace legacy operations,
> > like enable, disable, config and set_polarity.
> >
> > Signed-off-by: Song Chen <chensong_2000@xxxxxx>
> > ---
> >   drivers/staging/greybus/pwm.c | 46 +++++++++++++++--------------------
> >   1 file changed, 19 insertions(+), 27 deletions(-)
> >
> > diff --git a/drivers/staging/greybus/pwm.c b/drivers/staging/greybus/pwm.c
> > index 891a6a672378..e1889cf979b2 100644
> > --- a/drivers/staging/greybus/pwm.c
> > +++ b/drivers/staging/greybus/pwm.c
> > @@ -204,43 +204,35 @@ static void gb_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
> >   	gb_pwm_deactivate_operation(pwmc, pwm->hwpwm);
> >   }
> >   
> > -static int gb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> > -			 int duty_ns, int period_ns)
> > -{
> > -	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
> > -
> > -	return gb_pwm_config_operation(pwmc, pwm->hwpwm, duty_ns, period_ns);
> > -};
> > -
> > -static int gb_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
> > -			       enum pwm_polarity polarity)
> > +static int gb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> > +			const struct pwm_state *state)
> >   {
> > +	int ret;
> >   	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
> >   
> > -	return gb_pwm_set_polarity_operation(pwmc, pwm->hwpwm, polarity);
> > -};
> > -
> > -static int gb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> > -{
> > -	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);
> > +	/* set period and duty cycle*/
> > +	ret = gb_pwm_config_operation(pwmc, pwm->hwpwm, state->duty_cycle, state->period);
>
> gb_pwm_config_operation's 3rd parameter is an u32, so you're loosing
> bits here as state->duty_cycle is a u64. Ditto for period.

originally, pwm_apply_state --> pwm_apply_legacy --> gb_pwm_config --> 
gb_pwm_config_operation is also loosing bits, does it mean greybus can 
live with that?

Or redefine gb_pwm_config_request, switch duty and period to __le64?

> Also it would be nice if you go from
>
> 	.duty_cycle = A, .period = B, .enabled = 1
>
> to
>
> 	.duty_cycle = C, .period = D, .enabled = 0
>
> that C/D wasn't visible on the output pin. So please disable earlier
> (but keep enable at the end).

sorry, i don't quite understand this part, but is below code looking 
good to you?

static int gb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
			const struct pwm_state *state)
{
	int err;
	bool enabled = pwm->state.enabled;
	struct gb_pwm_chip *pwmc = pwm_chip_to_gb_pwm_chip(chip);

	/* set polarity */
	if (state->polarity != pwm->state.polarity) {
		if (enabled) {
			gb_pwm_disable_operation(pwmc, pwm->hwpwm);
			enabled = false;
		}
		err = gb_pwm_set_polarity_operation(pwmc, pwm->hwpwm, state->polarity);
		if (err)
			return err;
	}

	if (!state->enabled) {
		if (enabled)
			gb_pwm_disable_operation(pwmc, pwm->hwpwm);
		return 0;
	}

	/* set period and duty cycle*/
	err = gb_pwm_config_operation(pwmc, pwm->hwpwm, state->duty_cycle, 
state->period);
	if (err)
		return err;

	/* enable/disable */
	if (!enabled)
		return gb_pwm_enable_operation(pwmc, pwm->hwpwm);

	return 0;
}

> Best regards
> Uwe