From mboxrd@z Thu Jan  1 00:00:00 1970
From: clemens.gruber@pqgruber.com (Clemens Gruber)
Date: Mon, 12 Sep 2016 23:12:54 +0200
Subject: [PATCHv6 0/3] pwm: imx: support output polarity inversion
In-Reply-To: <20160912200021.fsnfdgnng4it354g@pengutronix.de>
References: <20141009151605.GA8818@ulmo.nvidia.com>
 <1412950949-7505-1-git-send-email-LW@KARO-electronics.de>
 <6c896634c4d6446df0388da2c0228232@agner.ch>
 <20160909091857.7a263220@ipc1.ka-ro>
 <20160912124553.aqgv7b4vsx4urogi@piout.net>
 <20160912140401.qkezay7sqqavsf4i@pengutronix.de>
 <074eed0df23199bc82f8d221690596d3@agner.ch>
 <20160912200021.fsnfdgnng4it354g@pengutronix.de>
Message-ID: <20160912211254.GA4637@archie.localdomain>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi Uwe,

On Mon, Sep 12, 2016 at 10:00:21PM +0200, Uwe Kleine-K?nig 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