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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Sat, 3 Oct 2020 11:17:58 +0300
Message-ID: <CAHp75VeSB4i_QNOX1UbrooNo0twqgbOhoaxnwk5a+=dEFWMzqA@mail.gmail.com>
Subject: Re: [PATCH v3 4/7] pwm: ntxec: Add driver for PWM function in
 Netronix EC
To:     =?UTF-8?Q?Jonathan_Neusch=C3=A4fer?= <j.neuschaefer@gmx.net>
Cc:     =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= 
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On Sat, Oct 3, 2020 at 2:36 AM Jonathan Neusch=C3=A4fer
<j.neuschaefer@gmx.net> wrote:
> On Mon, Sep 28, 2020 at 10:35:46AM +0200, Uwe Kleine-K=C3=B6nig wrote:
> > On Sun, Sep 27, 2020 at 11:10:44PM +0200, Jonathan Neusch=C3=A4fer wrot=
e:

...

> > You can even check this with an LED using something like:
> >
> >       pwm_apply(mypwm, {.enabled =3D true, .duty_cycle =3D $big, .perio=
d =3D $big});
> >       pwm_apply(mypwm, {.enabled =3D false, ... });
> >
> > . If the period is completed the LED is on for $big ns, if not the LED
> > is on for a timespan that is probably hardly noticable with the human
> > eye.
>
> The longest configurable period is about 8ms, so it's not long enough to
> see anything. However, after writing enable=3D0, it can take about a
> second for the PWM signal to turn off... this hardware is a bit weird.

Sounds like you have 1/128 divisor and off/on is done on lower
frequency. (We saw PWMs with an additional 7-bit counter, reminds me
Crystal Cove PMIC PWM).

--=20
With Best Regards,
Andy Shevchenko