Add documentation for PWM push-pull mode.
Signed-off-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx>
---
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
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