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From: Nylon Chen <nylon.chen@sifive.com>
Date: Tue, 2 Apr 2024 10:01:39 +0800
Message-ID: <CAHh=Yk92=hp+kaTJWL13_jwJ5gzAAi8gbRF=Ns9=yq2trRUQEg@mail.gmail.com>
Subject: Re: [PATCH v9 3/3] pwm: sifive: Fix the error in the idempotent test
 within the pwm_apply_state_debug function
To: =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
Cc: linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, 
	linux-kernel@vger.kernel.org, linux-pwm@vger.kernel.org, conor@kernel.org, 
	robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, palmer@dabbelt.com, 
	paul.walmsley@sifive.com, aou@eecs.berkeley.edu, thierry.reding@gmail.com, 
	vincent.chen@sifive.com, zong.li@sifive.com, nylon7717@gmail.com
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Uwe Kleine-K=C3=B6nig <u.kleine-koenig@pengutronix.de> =E6=96=BC 2024=E5=B9=
=B43=E6=9C=8819=E6=97=A5 =E9=80=B1=E4=BA=8C =E4=B8=8A=E5=8D=882:17=E5=AF=AB=
=E9=81=93=EF=BC=9A
>
> Hello,
>
> On Thu, Feb 22, 2024 at 04:12:31PM +0800, Nylon Chen wrote:
> > Round the result to the nearest whole number. This ensures that
> > real_period is always a reasonable integer that is not lower than the
> > actual value.
> >
> > e.g.
> > $ echo 110 > /sys/devices/platform/led-controller-1/leds/d12/brightness
> > $ .apply is not idempotent (ena=3D1 pol=3D0 1739692/4032985) -> (ena=3D=
1 pol=3D0 1739630/4032985)
> >
> > Co-developed-by: Zong Li <zong.li@sifive.com>
> > Signed-off-by: Zong Li <zong.li@sifive.com>
> > Signed-off-by: Nylon Chen <nylon.chen@sifive.com>
> > ---
> >  drivers/pwm/pwm-sifive.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
> > index a586cfe4191b..bebcbebacccd 100644
> > --- a/drivers/pwm/pwm-sifive.c
> > +++ b/drivers/pwm/pwm-sifive.c
> > @@ -101,7 +101,7 @@ static void pwm_sifive_update_clock(struct pwm_sifi=
ve_ddata *ddata,
> >
> >       /* As scale <=3D 15 the shift operation cannot overflow. */
> >       num =3D (unsigned long long)NSEC_PER_SEC << (PWM_SIFIVE_CMPWIDTH =
+ scale);
> > -     ddata->real_period =3D div64_ul(num, rate);
> > +     ddata->real_period =3D DIV_ROUND_UP_ULL(num, rate);
> >       dev_dbg(ddata->chip.dev,
> >               "New real_period =3D %u ns\n", ddata->real_period);
> >  }
Hi Uwe
>
> pwm_sifive_apply has a DIV64_U64_ROUND_CLOSEST(). I wonder if that needs
> adaption, too?!
According to my experiments, no adjustment is necessary.
>
> Best regards
> Uwe
>
> --
> Pengutronix e.K.                           | Uwe Kleine-K=C3=B6nig       =
     |
> Industrial Linux Solutions                 | https://www.pengutronix.de/ =
|