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From: linux@roeck-us.net (Guenter Roeck)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 6/6] hwmon: pwm-fan: Update the duty cycle inorder to control the pwm-fan
Date: Fri, 10 Apr 2015 10:58:01 -0700	[thread overview]
Message-ID: <20150410175801.GA31499@roeck-us.net> (raw)
In-Reply-To: <87h9snvqsf.fsf@gmail.com>

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

  reply	other threads:[~2015-04-10 17:58 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-26 16:39 Exynos5422 odroidxu3 pwm-fan control using thermal sensors Anand Moon
2015-03-26 16:39 ` [PATCH 1/6] ARM: dts :exynos5422-odroidxu3 Add pwm-fan node to the Odroid-XU3 board Anand Moon
2015-04-08  7:46   ` Lukasz Majewski
2015-03-26 16:39 ` [PATCH 2/6] ARM: dts exynos5420 update the cooling cells for core cpu0 Anand Moon
2015-04-08  7:47   ` Lukasz Majewski
2015-03-26 16:39 ` [PATCH 3/6] ARM:dts exynos5422 Update the thermal sensor for tmu_cpu0 Anand Moon
2015-04-08  8:02   ` Lukasz Majewski
2015-04-08  9:12     ` Anand Moon
2015-04-08  9:30       ` Lukasz Majewski
2015-04-08  9:44         ` Anand Moon
2015-03-26 16:39 ` [PATCH 4/6] ARM: dts: OdroidXU3: Enable TMU at Exynos5422 base Anand Moon
2015-04-08  8:03   ` Lukasz Majewski
2015-03-26 16:39 ` [PATCH 5/6] pwm: samsung: Fix output race on disabling Anand Moon
2015-04-08  8:28   ` Lukasz Majewski
2015-04-08  8:42     ` Sjoerd Simons
2015-04-08  8:53       ` Anand Moon
2015-03-26 16:39 ` [PATCH 6/6] hwmon: pwm-fan: Update the duty cycle inorder to control the pwm-fan Anand Moon
2015-04-08  8:44   ` Lukasz Majewski
2015-04-08 13:11     ` Guenter Roeck
2015-04-08 15:32     ` Guenter Roeck
2015-04-08 16:02       ` Anand Moon
2015-04-08 16:53         ` Guenter Roeck
2015-04-08 17:49           ` Anand Moon
2015-04-10 11:28             ` Anand Moon
2015-04-10 12:00               ` Sjoerd Simons
2015-04-10 12:59                 ` Anand Moon
2015-04-10 13:09                   ` Guenter Roeck
2015-04-10 13:17                     ` Anand Moon
2015-04-10 13:30                     ` Sjoerd Simons
2015-04-10 13:58                       ` Thierry Reding
2015-04-10 17:25                         ` Ben Gamari
2015-04-10 17:58                           ` Guenter Roeck [this message]
2015-04-02 10:02 ` Exynos5422 odroidxu3 pwm-fan control using thermal sensors Markus Reichl
2015-04-02 10:06 ` Markus Reichl

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