Messages in this thread | | | Date | Fri, 3 Mar 2023 22:17:25 +0100 | From | Uwe Kleine-König <> | Subject | Re: [PATCH] pwm: mediatek: support inverted polarity |
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On Fri, Mar 03, 2023 at 09:58:21PM +0100, Lorenz Brun wrote: > According to the MT7986 Reference Manual the Mediatek PWM controller > doesn't appear to have support for inverted polarity. > > This implements the same solution as in pwm-meson and just inverts the > duty cycle instead, which results in the same outcome.
This idea is broken. This was recently discussed on the linux-pwm list and I hope will be fixed soon. See https://lore.kernel.org/linux-pwm/20230228093911.bh2sbp4tyfir2z5g@pengutronix.de/T/#meda75ffbd4ef2048991ea2cd091c0c14b1bb09c2
So this patch won't be accepted, still pointing out a style problem below.
> Signed-off-by: Lorenz Brun <lorenz@brun.one> > --- > drivers/pwm/pwm-mediatek.c | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > > diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c > index 5b5eeaff35da..6f4a54c8299f 100644 > --- a/drivers/pwm/pwm-mediatek.c > +++ b/drivers/pwm/pwm-mediatek.c > @@ -202,9 +202,7 @@ static int pwm_mediatek_apply(struct pwm_chip *chip, struct pwm_device *pwm, > const struct pwm_state *state) > { > int err; > - > - if (state->polarity != PWM_POLARITY_NORMAL) > - return -EINVAL; > + u64 duty_cycle; > > if (!state->enabled) { > if (pwm->state.enabled) > @@ -213,7 +211,14 @@ static int pwm_mediatek_apply(struct pwm_chip *chip, struct pwm_device *pwm, > return 0; > } > > - err = pwm_mediatek_config(pwm->chip, pwm, state->duty_cycle, state->period); > + // According to the MT7986 Reference Manual the peripheral does not > + // appear to have the capability to invert the output. Instead just > + // invert the duty cycle.
Wrong commenting style, please stick to C-style comments (/* ... */)
> + duty_cycle = state->duty_cycle; > + if (state->polarity == PWM_POLARITY_INVERSED) > + duty_cycle = state->period - state->duty_cycle; > + > + err = pwm_mediatek_config(pwm->chip, pwm, duty_cycle, state->period); > if (err) > return err;
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ | [unhandled content-type:application/pgp-signature] | |