From mboxrd@z Thu Jan 1 00:00:00 1970 From: Claudiu Beznea Subject: [PATCH v2 15/16] pwm: add documentation for pwm push-pull mode Date: Fri, 12 Jan 2018 16:23:02 +0200 Message-ID: <1515766983-15151-16-git-send-email-claudiu.beznea@microchip.com> References: <1515766983-15151-1-git-send-email-claudiu.beznea@microchip.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <1515766983-15151-1-git-send-email-claudiu.beznea@microchip.com> Sender: linux-kernel-owner@vger.kernel.org To: thierry.reding@gmail.com, robh+dt@kernel.org, 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 Cc: 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, Claudiu Beznea List-Id: devicetree@vger.kernel.org Add documentation for PWM push-pull mode. Signed-off-by: Claudiu Beznea --- Documentation/devicetree/bindings/pwm/pwm.txt | 8 +++++++- Documentation/pwm.txt | 18 ++++++++++++++++++ 2 files changed, 25 insertions(+), 1 deletion(-) diff --git a/Documentation/devicetree/bindings/pwm/pwm.txt b/Documentation/devicetree/bindings/pwm/pwm.txt index fdff25bad1db..a4562af3577c 100644 --- a/Documentation/devicetree/bindings/pwm/pwm.txt +++ b/Documentation/devicetree/bindings/pwm/pwm.txt @@ -58,15 +58,21 @@ Example with optional PWM specifier for inverse polarity - PWM_MODE_NORMAL: for all PWM controllers - PWM_MODE_COMPLEMENTARY: for PWM controllers with more than one output per PWM channel +- PWM_MODE_PUSH_PULL: for PWM controllers with more than one output per channel, +in push-pull mode Example with PWM modes: bl: blacklight { pwms = <&pwm 0 5000000 PWM_POLARITY_INVERTED - PWM_DTMODE_NORMAL | PWM_DTMODE_COMPLEMENTARY>; + PWM_DTMODE_NORMAL | PWM_DTMODE_COMPLEMENTARY | + PWM_DTMODE_PUSH_PULL>; pwm-names = "backlight"; }; +If all the available modes are given as argument of pwms binding only the first +valid one will be considered (first valid LSB bit of mode field). + 2) PWM controller nodes ----------------------- diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt index 58c9bd55f021..71b538239519 100644 --- a/Documentation/pwm.txt +++ b/Documentation/pwm.txt @@ -135,6 +135,24 @@ channel that was exported. The following properties will then be available: Where T is the signal period. + Push-pull mode - for PWM chips with mode than one output per PWM channel; + output waveform for a PWM controller with 2 outputs per PWM channel, in + push-pull mode, with normal polarity looks like this: + __ __ + PWMH __| |________| |________ + __ __ + PWML ________| |________| |__ + <--T--> + + If polarity is inversed: + __ ________ ________ + PWMH |__| |__| + ________ ________ __ + PWML |__| |__| + <--T--> + + Where T is the signal period. + Implementing a PWM driver ------------------------- -- 2.7.4