[v7,5/6] pwm: add documentation for pwm push-pull mode

Commit Message

Claudiu Beznea Dec. 17, 2018, 2:13 p.m. UTC

From: Claudiu Beznea <[e-mail]>

Add documentation for PWM push-pull mode.

Signed-off-by: Claudiu Beznea <[e-mail]>
---

Hi Rob,                                                                         
                                                                                
In prevous version I had your Reviewed-by tag on this patch but I removed it       
in this version since there are some changes b/w the previous one and this      
one. Please see bellow and let me know if you are ok with this.                                                        

Thank you,
Claudiu Beznea

Changes in v6:
- remove bindings part
- use 1/3 duty factor ratio
- use '^' symbols to emphasize the beginning of a new period
- use PWMx_y to refrer to output y of PWM x

 Documentation/pwm.txt | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

Patch

diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt
index 669fd4c9cc8e..80552627627d 100644
--- a/Documentation/pwm.txt
+++ b/Documentation/pwm.txt
@@ -130,6 +130,22 @@  channel that was exported. The following properties will then be available:
     PWMx_1   |__|    |__|    |__|    |__|
              ^       ^       ^       ^
 
+    Push-pull mode - for PWM channels with two outputs; output waveforms
+        for a PWM channel in push-pull mode, with normal polarity looks like
+        this:
+              __              __
+    PWMx_0 __|  |____________|  |__________
+                      __              __
+    PWMx_1 __________|  |____________|  |__
+             ^       ^       ^       ^
+
+    If polarity is inversed:
+           __    ____________    __________
+    PWMx_0   |__|            |__|
+           __________    ____________    __
+    PWMx_1           |__|            |__|
+             ^       ^       ^       ^
+
     Where '^' specifies the beginning of a period.
 
 Implementing a PWM driver