Re: RFC: don't let drivers issue pwm_disable after pwm_config(pwm, 0, period)

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

Hello Thierry,

On Thu, Sep 27, 2018 at 10:29:55PM +0200, Thierry Reding wrote:
> On Thu, Sep 27, 2018 at 08:26:07PM +0200, Uwe Kleine-König wrote:
> > On Fri, Sep 21, 2018 at 06:02:30PM +0200, Uwe Kleine-König wrote:
> > > On Tue, Sep 04, 2018 at 10:37:24PM +0200, Uwe Kleine-König wrote:
> > > > On Mon, Aug 20, 2018 at 11:52:21AM +0200, Uwe Kleine-König wrote:
> > > > > On Thu, Aug 09, 2018 at 05:23:30PM +0200, Uwe Kleine-König wrote:
> > > > > > On Thu, Aug 09, 2018 at 01:30:54PM +0200, Thierry Reding wrote:
> > > > > > > I don't see how you could make that work. In practically all cases a
> > > > > > > pwm_disable() would have to be assumed to cause the pin level to become
> > > > > > > undefined. That makes it pretty much useless.
> > > > > > 
> > > > > > Right, that's what I want. pwm_disable() should make no guarantees about
> > > > > > the pin level. [...]
> > > > > >
> > > > > > > I agree that this is simpler and clearer. However it also significantly
> > > > > > > reduces the flexibility of the API, and I'm not sure that it is enough.
> > > > > > > Again, yes, for many cases this is sufficient, but it doesn't fully
> > > > > > > expose the capabilities of hardware.
> > > > > > 
> > > > > > Can you show me a use case that isn't possible to express with the
> > > > > > suggested change in semantic?
> > > > > 
> > > > > To get forward here the only missing points are:
> > > > > 
> > > > >  a) Your claim that this simplification looses expressive power.
> > > > >  b) Actually convert the users (assuming a) can be resolved)
> > > > > 
> > > > > I cannot find a usecase that cannot be handled with the suggested change
> > > > > in semantic. So can I lure you in explaining what setup you have in
> > > > > mind?
> > > > 
> > > > I'd really like to get forward here, so you feedback would be very
> > > > welcome. What is the use case you have in mind when writing "it also
> > > > significantly reduces the flexibility of the API, and I'm not sure that
> > > > it is enough"?
> > > 
> > > I'm a bit irritated that you don't continue to communicate here. On
> > > August 9 I had the impression that we can discuss this topic to an end.
> > > But as you stopped replying we unfortunately cannot :-|
> > 
> > Seeing you reply on other topics I wonder what is the problem here. Can
> > you at least quickly confirm that you received my mails?
> 
> Confirming that I'm receiving your emails. Sorry, but I haven't found
> the necessary time to look at the details here any closer to continue
> the discussion in a meaningful way.
> 
> I will hopefully get around to it within the next couple of days.

I would really like to continue this discussion before it is swapped out
of my mind again.

Did you find the time to consider my thoughts?

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |