From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Lee Jones <lee.jones@linaro.org>
Cc: "Michael Walle" <michael@walle.cc>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
devicetree <devicetree@vger.kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
linux-hwmon@vger.kernel.org, linux-pwm@vger.kernel.org,
linux-watchdog@vger.kernel.org,
"linux-arm Mailing List" <linux-arm-kernel@lists.infradead.org>,
"Linus Walleij" <linus.walleij@linaro.org>,
"Bartosz Golaszewski" <bgolaszewski@baylibre.com>,
"Rob Herring" <robh+dt@kernel.org>,
"Jean Delvare" <jdelvare@suse.com>,
"Guenter Roeck" <linux@roeck-us.net>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
"Wim Van Sebroeck" <wim@linux-watchdog.org>,
"Shawn Guo" <shawnguo@kernel.org>, "Li Yang" <leoyang.li@nxp.com>
Subject: Re: [PATCH v4 05/11] pwm: add support for sl28cpld PWM controller
Date: Fri, 5 Jun 2020 12:33:01 +0300 [thread overview]
Message-ID: <CAHp75VfTAasC319uXz82dDufdnTGFhTnzJPXknk2+w-rnFfXTg@mail.gmail.com> (raw)
In-Reply-To: <20200605084915.GE3714@dell>
On Fri, Jun 5, 2020 at 11:51 AM Lee Jones <lee.jones@linaro.org> wrote:
> On Thu, 04 Jun 2020, Michael Walle wrote:
...
> > + cycle = state->duty_cycle * config->max_duty_cycle;
> > + do_div(cycle, state->period);
>
> Forgive my ignorance (I'm new here!), but what are these 2 lines
> doing? Here we are multiplying the current duty_cycle with the
> maximum value, then dividing by the period.
>
> So in the case of PWM_MODE_1KHZ with a 50% duty cycle, you'd have:
>
> (500000 * 0x20[16]) / 1000000 = [0x10]16
>
> Thus, the above gives as a proportional representation of the maximum
> valid value for placement into the cycle control register(s), right?
>
> Either way (whether I'm correct or not), I think it would be nice to
> mention this in a comment. Maybe even clarify with a simple example.
IIRC PWM has a helper for that (to calc period based on PWM state and
new duty cycle %).
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2020-06-05 9:33 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-04 21:10 [PATCH v4 00/11] Add support for Kontron sl28cpld Michael Walle
2020-06-04 21:10 ` [PATCH v4 01/11] dt-bindings: mfd: Add bindings for sl28cpld Michael Walle
2020-06-09 16:28 ` Rob Herring
2020-06-04 21:10 ` [PATCH v4 02/11] mfd: Add support for Kontron sl28cpld management controller Michael Walle
[not found] ` <20200604211039.12689-3-michael-QKn5cuLxLXY@public.gmane.org>
2020-06-05 6:57 ` Lee Jones
2020-06-05 9:51 ` Michael Walle
2020-06-05 10:50 ` Mark Brown
[not found] ` <20200605105026.GC5413-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2020-06-05 20:07 ` Michael Walle
2020-06-06 11:46 ` Mark Brown
2020-06-06 12:45 ` Michael Walle
[not found] ` <dc052a5c77171014ecc465b1da8b7ef8-QKn5cuLxLXY@public.gmane.org>
2020-06-08 8:28 ` Lee Jones
2020-06-08 10:02 ` Andy Shevchenko
2020-06-08 15:41 ` Michael Walle
2020-06-08 18:56 ` Lee Jones
2020-06-08 21:09 ` Michael Walle
[not found] ` <32231f26f7028d62aeda8fdb3364faf1-QKn5cuLxLXY@public.gmane.org>
2020-06-09 6:47 ` Lee Jones
2020-06-09 14:38 ` Michael Walle
2020-06-09 14:42 ` Mark Brown
2020-06-09 15:01 ` Michael Walle
[not found] ` <a2bae71634fe288f067d5e92090b7561-QKn5cuLxLXY@public.gmane.org>
2020-06-09 17:15 ` Rob Herring
2020-06-09 17:29 ` Mark Brown
2020-06-09 18:41 ` Lee Jones
2020-06-09 15:19 ` Lee Jones
2020-06-09 15:30 ` Michael Walle
2020-06-09 19:45 ` Lee Jones
2020-06-10 7:10 ` Michael Walle
2020-06-10 7:19 ` Lee Jones
2020-06-10 7:49 ` Michael Walle
2020-06-10 7:56 ` Lee Jones
2020-06-10 9:27 ` Michael Walle
2020-06-10 18:30 ` Lee Jones
2020-06-10 17:16 ` Rob Herring
2020-06-10 18:02 ` Lee Jones
2020-06-08 18:20 ` Lee Jones
2020-06-09 16:54 ` Rob Herring
2020-06-09 18:52 ` Lee Jones
2020-06-05 8:01 ` Andy Shevchenko
2020-06-05 8:02 ` Andy Shevchenko
2020-06-05 10:09 ` Michael Walle
2020-06-05 10:48 ` Andy Shevchenko
2020-06-05 11:51 ` Michael Walle
2020-06-04 21:10 ` [PATCH v4 03/11] irqchip: add sl28cpld interrupt controller support Michael Walle
2020-06-05 1:26 ` kernel test robot
2020-06-05 8:07 ` Andy Shevchenko
2020-06-08 15:12 ` kernel test robot
2020-06-04 21:10 ` [PATCH v4 04/11] watchdog: add support for sl28cpld watchdog Michael Walle
2020-06-05 8:14 ` Andy Shevchenko
2020-06-05 10:24 ` Michael Walle
[not found] ` <8f042c2442852c29519c381833f3d289-QKn5cuLxLXY@public.gmane.org>
2020-06-05 10:50 ` Andy Shevchenko
2020-06-05 13:52 ` Guenter Roeck
[not found] ` <871a4990-5b94-3a17-01d4-74998375f08b-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
2020-06-05 14:09 ` Andy Shevchenko
2020-06-05 15:05 ` Guenter Roeck
2020-06-05 16:04 ` Andy Shevchenko
[not found] ` <CAHp75VduUG=XkvyZwdZDNqBh3KE67MWZWgqBN67fN6StAa469w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2020-06-05 16:34 ` Guenter Roeck
2020-06-04 21:10 ` [PATCH v4 06/11] gpio: add support for the sl28cpld GPIO controller Michael Walle
[not found] ` <20200604211039.12689-7-michael-QKn5cuLxLXY@public.gmane.org>
2020-06-05 12:00 ` Andy Shevchenko
2020-06-05 12:42 ` Michael Walle
2020-06-05 13:15 ` Andy Shevchenko
2020-06-05 18:44 ` Michael Walle
2020-06-05 21:19 ` Andy Shevchenko
[not found] ` <20200604211039.12689-1-michael-QKn5cuLxLXY@public.gmane.org>
2020-06-04 21:10 ` [PATCH v4 05/11] pwm: add support for sl28cpld PWM controller Michael Walle
2020-06-05 8:15 ` Andy Shevchenko
2020-06-05 8:49 ` Lee Jones
2020-06-05 9:33 ` Andy Shevchenko [this message]
2020-06-05 11:39 ` Michael Walle
2020-06-05 18:17 ` Michael Walle
2020-06-08 7:46 ` Lee Jones
2020-06-04 21:10 ` [PATCH v4 07/11] hwmon: add support for the sl28cpld hardware monitoring controller Michael Walle
2020-06-05 12:06 ` Andy Shevchenko
2020-06-04 21:10 ` [PATCH v4 08/11] arm64: dts: freescale: sl28: enable sl28cpld Michael Walle
2020-06-04 21:10 ` [PATCH v4 09/11] arm64: dts: freescale: sl28: map GPIOs to input events Michael Walle
2020-06-04 21:10 ` [PATCH v4 10/11] arm64: dts: freescale: sl28: enable LED support Michael Walle
2020-06-04 21:10 ` [PATCH v4 11/11] arm64: dts: freescale: sl28: enable fan support Michael Walle
2020-06-05 6:13 ` [PATCH v4 00/11] Add support for Kontron sl28cpld Lee Jones
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