Re: [PATCHv6 0/3] pwm: imx: support output polarity inversion

[Clemens Gruber <clemens.gruber@pqgruber.com>]

Hi Uwe,

On Mon, Sep 12, 2016 at 10:00:21PM +0200, Uwe Kleine-König wrote:
> I want that the pwm driver disables its clock on pwm_config(mypwm, 0,
> someperiod) such that the consumer doesn't need to call
> pwm_disable(mypwm) to save power (assuming it's safe to do so, which
> only the pwm provider knows).

I am not sure if this is such a good idea, because there are use cases
where you want to keep the PWM driver enabled the whole time but still
be able to change the duty cycle to 0 for some time without adding
unnecessary delays when changing the duty cycle back to something else.

We have an application where we control fluid valves in a beer
dispensing system through PWMs and these valves are pulsed with
different PWM duty cycles for a short time. In-between the duty cycle
is also 0. For example: Start at 0%, 100ms 90%, 200ms 70%, 300ms 0%,
100ms 90%, and so on..
There it is critical that the change from and to 0 duty cycle is not
delayed by disabling and reenabling the clock.
The oscillator (if there is one) should be up and running, only the duty
cycle should be 0 for a short time.

This would not be possible anymore with your API change, right?

Regards,
Clemens