From: Rob Herring <robh@kernel.org>
To: Claudiu Beznea <claudiu.beznea@microchip.com>
Cc: thierry.reding@gmail.com, mark.rutland@arm.com,
linux@armlinux.org.uk, daniel@zonque.org,
haojian.zhuang@gmail.com, robert.jarzmik@free.fr, corbet@lwn.net,
nicolas.ferre@microchip.com,
alexandre.belloni@free-electrons.com, linux-pwm@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-amlogic@lists.infradead.org,
linux-rockchip@lists.infradead.org,
linux-rpi-kernel@lists.infradead.org, devicetree@vger.kernel.org
Subject: Re: [PATCH v2 11/16] pwm: add documentation for PWM modes
Date: Fri, 19 Jan 2018 16:39:08 -0600 [thread overview]
Message-ID: <20180119223908.b3dxdx53nzuhakzw@rob-hp-laptop> (raw)
In-Reply-To: <1515766983-15151-12-git-send-email-claudiu.beznea@microchip.com>
On Fri, Jan 12, 2018 at 04:22:58PM +0200, Claudiu Beznea wrote:
> Add documentation for PWM normal and complementary modes.
This and the previous patch can be combined.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
> ---
> Documentation/devicetree/bindings/pwm/pwm.txt | 17 ++++++++++++++--
> Documentation/pwm.txt | 29 +++++++++++++++++++++++++--
> 2 files changed, 42 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/pwm/pwm.txt b/Documentation/devicetree/bindings/pwm/pwm.txt
> index 8556263b8502..fdff25bad1db 100644
> --- a/Documentation/devicetree/bindings/pwm/pwm.txt
> +++ b/Documentation/devicetree/bindings/pwm/pwm.txt
> @@ -43,8 +43,8 @@ because the name "backlight" would be used as fallback anyway.
> pwm-specifier typically encodes the chip-relative PWM number and the PWM
> period in nanoseconds.
>
> -Optionally, the pwm-specifier can encode a number of flags (defined in
> -<dt-bindings/pwm/pwm.h>) in a third cell:
> +Optionally, the pwm-specifier can encode:
> +1. a number of flags (defined in <dt-bindings/pwm/pwm.h>) in a third cell:
Based on the prior patches, "third cell" is probably to restrictive
here and it should just say "in a flags cell".
> - PWM_POLARITY_INVERTED: invert the PWM signal polarity
>
> Example with optional PWM specifier for inverse polarity
> @@ -54,6 +54,19 @@ Example with optional PWM specifier for inverse polarity
> pwm-names = "backlight";
> };
>
> +2. PWM working modes (defined in <dt-bindings/pwm/pwm.h>) in the 4th cell:
> +- PWM_MODE_NORMAL: for all PWM controllers
> +- PWM_MODE_COMPLEMENTARY: for PWM controllers with more than one output per
> +PWM channel
> +
> +Example with PWM modes:
> +
> + bl: blacklight {
> + pwms = <&pwm 0 5000000 PWM_POLARITY_INVERTED
> + PWM_DTMODE_NORMAL | PWM_DTMODE_COMPLEMENTARY>;
> + pwm-names = "backlight";
> + };
> +
> 2) PWM controller nodes
> -----------------------
>
> diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt
> index 8fbf0aa3ba2d..58c9bd55f021 100644
> --- a/Documentation/pwm.txt
> +++ b/Documentation/pwm.txt
> @@ -61,8 +61,8 @@ In addition to the PWM state, the PWM API also exposes PWM arguments, which
> are the reference PWM config one should use on this PWM.
> PWM arguments are usually platform-specific and allows the PWM user to only
> care about dutycycle relatively to the full period (like, duty = 50% of the
> -period). struct pwm_args contains 2 fields (period and polarity) and should
> -be used to set the initial PWM config (usually done in the probe function
> +period). struct pwm_args contains 3 fields (period, polarity and mode) and
> +should be used to set the initial PWM config (usually done in the probe function
> of the PWM user). PWM arguments are retrieved with pwm_get_args().
>
> Using PWMs with the sysfs interface
> @@ -83,6 +83,9 @@ will find:
> unexport
> Unexports a PWM channel from sysfs (write-only).
>
> + mode
> + PWM chip supported modes.
> +
> The PWM channels are numbered using a per-chip index from 0 to npwm-1.
>
> When a PWM channel is exported a pwmX directory will be created in the
> @@ -110,6 +113,28 @@ channel that was exported. The following properties will then be available:
> - 0 - disabled
> - 1 - enabled
>
> + mode
> + Set PWM channel working mode (normal and complementary). PWM chip with
> + complementary mode could also work in normal mode by using only one physical
> + output.
> +
> + Normal mode - for PWM chips with one output per PWM channel; output
> + waveforms looks like this:
> + __ __ __ __
> + PWM __| |__| |__| |__| |__
> + <--T-->
> +
> + Complementary mode - for PWM chips with more than one output per PWM
> + channel; output waveforms for a PWM controller with 2 outputs per PWM
> + channel looks line this:
> + __ __ __ __
> + PWMH1 __| |__| |__| |__| |__
> + __ __ __ __ __
> + PWML1 |__| |__| |__| |__|
> + <--T-->
> +
> + Where T is the signal period.
> +
> Implementing a PWM driver
> -------------------------
>
> --
> 2.7.4
>
next prev parent reply other threads:[~2018-01-19 22:39 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-12 14:22 [PATCH v2 00/16] extend PWM framework to support PWM modes Claudiu Beznea
2018-01-12 14:22 ` [PATCH v2 01/16] drivers: pwm: core: use a single of xlate function Claudiu Beznea
[not found] ` <1515766983-15151-2-git-send-email-claudiu.beznea-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org>
2018-01-12 18:35 ` Brian Norris
[not found] ` <20180112183512.GB102880-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2018-01-15 8:41 ` Claudiu Beznea
2018-01-15 12:43 ` Claudiu Beznea
2018-01-15 20:27 ` Andy Shevchenko
[not found] ` <CAHp75VcaFDEQ1cBzeU2eBj_vf19ok6EWLC07SOTQLRH8BQSbzA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-01-16 8:24 ` Claudiu Beznea
2018-01-17 23:14 ` Brian Norris
2018-01-18 9:11 ` Claudiu Beznea
2018-01-16 9:07 ` Neil Armstrong
2018-01-16 9:33 ` Claudiu Beznea
2018-01-12 14:22 ` [PATCH v2 02/16] pwm: pxa: update documentation regarding pwm-cells Claudiu Beznea
2018-01-19 22:30 ` Rob Herring
2018-01-22 8:47 ` Claudiu Beznea
2018-01-12 14:22 ` [PATCH v2 04/16] pwm: clps711x: " Claudiu Beznea
2018-01-12 14:22 ` [PATCH v2 05/16] ARM: dts: clps711x: update pwm-cells Claudiu Beznea
2018-01-12 14:22 ` [PATCH v2 07/16] arm64: dts: rockchip: " Claudiu Beznea
2018-01-12 14:22 ` [PATCH v2 08/16] drivers: pwm: core: extend PWM framework with PWM modes Claudiu Beznea
2018-01-12 14:22 ` [PATCH v2 10/16] pwm: Add " Claudiu Beznea
2018-01-19 22:34 ` Rob Herring
2018-01-22 8:54 ` Claudiu Beznea
[not found] ` <c5aeb8df-6aa8-cde4-9305-08777cac2f45-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org>
2018-01-22 18:12 ` Rob Herring
[not found] ` <CAL_JsqJho2OrdnHwRPpYsbNB4RFTq5qSLA=36D2zy=Mi7B8XwQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-01-23 10:40 ` Claudiu Beznea
2018-01-23 15:21 ` Rob Herring
2018-01-23 16:55 ` Claudiu Beznea
[not found] ` <1515766983-15151-1-git-send-email-claudiu.beznea-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org>
2018-01-12 14:22 ` [PATCH v2 03/16] pwm: cros-ec: update documentation regarding pwm-cells Claudiu Beznea
2018-01-12 18:31 ` Brian Norris
2018-01-15 9:01 ` Claudiu Beznea
2018-01-17 8:29 ` Claudiu Beznea
[not found] ` <c2078487-8cc6-429e-6c38-092d776c33aa-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org>
2018-01-17 23:10 ` Brian Norris
2018-01-18 9:18 ` Claudiu Beznea
2018-01-12 14:22 ` [PATCH v2 06/16] ARM: dts: pxa: update pwm-cells Claudiu Beznea
2018-01-12 14:22 ` [PATCH v2 09/16] drivers: pwm: core: add PWM mode to pwm_config() Claudiu Beznea
2018-01-12 14:22 ` [PATCH v2 11/16] pwm: add documentation for PWM modes Claudiu Beznea
2018-01-19 22:39 ` Rob Herring [this message]
2018-01-22 8:55 ` Claudiu Beznea
2018-01-12 14:23 ` [PATCH v2 13/16] drivers: pwm: core: add push-pull mode support Claudiu Beznea
2018-01-12 14:22 ` [PATCH v2 12/16] pwm: atmel: add pwm capabilities Claudiu Beznea
2018-01-12 14:23 ` [PATCH v2 14/16] pwm: add push-pull mode Claudiu Beznea
2018-01-12 14:23 ` [PATCH v2 15/16] pwm: add documentation for pwm " Claudiu Beznea
[not found] ` <1515766983-15151-16-git-send-email-claudiu.beznea-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org>
2018-01-19 22:41 ` Rob Herring
2018-01-12 14:23 ` [PATCH v2 16/16] pwm: atmel: add push-pull mode support Claudiu Beznea
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