pwm: Document that the pinstate of a disabled PWM isn't reliable
Some (most?) drivers emit the inactive state when the PWM is disabled.
However there are exceptions, so document that a consumer better doesn't
depend on this behaviour.
Some known exceptions:
- imx27 emits 0 independent of the configured polarity
- mxs just drives the output to the last emitted state.
- iqs620a makes the output tristated on disable, so an external
pull-down would be required.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>