[PATCH] PWM: Document disabled PWM output as undefined

[Sascha Hauer]

When disabled PWM hardware reacts differently. Some controllers
just stop with their current value, others produce a constant high
or low output, sometimes depending on the output inversion bit. Update
the documentation to reflect that and request from the PWM consumer
drivers to set a constant high/low value with duty cycles of 0/100%
instead of disabling the PWM.

Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
---
 Documentation/pwm.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt
index 93cb979..b7e8a31 100644
--- a/Documentation/pwm.txt
+++ b/Documentation/pwm.txt
@@ -44,6 +44,8 @@ After being requested, a PWM has to be configured using:
 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns);
 
 To start/stop toggling the PWM output use pwm_enable()/pwm_disable().
+The output of a disabled PWM is undefined. Set the duty cycle to 100%
+for a constant high output and to 0 for constant low output.
 
 Using PWMs with the sysfs interface
 -----------------------------------
-- 
1.8.5.2

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