lkml.org 
[lkml]   [2015]   [Apr]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 6/6] hwmon: pwm-fan: Update the duty cycle inorder to control the pwm-fan
On Fri, Apr 10, 2015 at 01:25:52PM -0400, Ben Gamari wrote:
> Thierry Reding <thierry.reding@gmail.com> writes:
>
> > On Fri, Apr 10, 2015 at 03:30:01PM +0200, Sjoerd Simons wrote:
> >>
> >> Yes/no/maybe :). Imho this is something to clarify in the pwm API
> >> documentation. As currently all it says is:
> >> "pwm_disable - stop a PWM output toggling",
> >>
> >> Which is what the exynos driver does.
> >>
> >> Thierry, could you clearify what the intention is here? I'm happy to
> >> prepare a pwm driver patch if needed to solve this?
> >
> > I think the safest thing to do is for users to do both. You call
> > pwm_config() with a zero duty cycle to make it clear what the status is
> > that you want. Then you call pwm_disable() to state that you don't need
> > the output signal anymore, so that any clocks needed by the PWM can be
> > stopped. Doing so gives the driver the most information and should make
> > the user more resilient against any possible quirks in drivers.
> >
> It would be great if the documentation were more clear on this matter
> regardless. This is something I can imagine having to spend substantial
> amounts of time Googling whereas a simple note in the documentation would
> have removed all ambiguity.
>
Especially since, in this case, the output signal _is_ still needed.
It appears that pwm_disable() is only expected to stop the clock, not
the signal itself.

Guenter


\
 
 \ /
  Last update: 2015-04-10 20:41    [W:0.060 / U:3.924 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site