Re: [PATCH 1/4] gpio: mvebu: Add limited PWM support

From: Andrew Lunn <andrew@lunn.ch>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Ralph Sennhauser <ralph.sennhauser@gmail.com>,
	"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
	Imre Kaloz <kaloz@openwrt.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	Alexandre Courbot <gnurou@gmail.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"David S. Miller" <davem@davemloft.net>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Guenter Roeck <linux@roeck-us.net>,
	"open list:PWM SUBSYSTEM" <linux-pwm@vger.kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/4] gpio: mvebu: Add limited PWM support
Date: Sat, 18 Mar 2017 16:37:53 +0100	[thread overview]
Message-ID: <20170318153753.GA22088@lunn.ch> (raw)
In-Reply-To: <CACRpkdZ=bor380ic_X36M7vVbopDCZe9Yb9TxkmOHyO75gdAnw@mail.gmail.com>

> > +static void mvebu_pwm_free(struct pwm_chip *chip, struct pwm_device *pwmd)
> > +{
> > +       struct mvebu_pwm *pwm = to_mvebu_pwm(chip);
> > +       struct gpio_desc *desc = gpio_to_desc(pwmd->pwm);
> > +       unsigned long flags;
> > +
> > +       spin_lock_irqsave(&pwm->lock, flags);
> > +       gpiod_free(desc);
> > +       pwm->used = false;
> > +       spin_unlock_irqrestore(&pwm->lock, flags);
> > +}
> 
> No need to set the output value to zero or something here?
> And turn off blinking? Or is that done some other way?

Hi Linus

The disable op will turn of blinking. I've not checked, but i assume
the PWM core will not allow you to free an enabled PWM?

> I think both of these need to be tagged __maybe_unused to not give
> noise in randconfig builds.

I've not seen any 0-day patch emails giving warnings. So i suspect it
is O.K.

   Andrew