linux-kernel - Re: [PATCH 1/2] GPIO: Add driver for Zynq GPIO controller

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Date:	Mon, 7 Apr 2014 12:00:05 -0700
From:	Sören Brinkmann <soren.brinkmann@...inx.com>
To:	Ulf Hansson <ulf.hansson@...aro.org>
CC:	Harini Katakam <harinik@...inx.com>,
	Mark Rutland <mark.rutland@....com>, <gnurou@...il.com>,
	Pawel Moll <pawel.moll@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Linus Walleij <linus.walleij@...aro.org>,
	<linux-doc@...r.kernel.org>, <michal.simek@...inx.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	<linux-gpio@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Rob Herring <robh+dt@...nel.org>, <michals@...inx.com>,
	Rob Landley <rob@...dley.net>,
	Kumar Gala <galak@...eaurora.org>,
	Grant Likely <grant.likely@...aro.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/2] GPIO: Add driver for Zynq GPIO controller

On Mon, 2014-03-31 at 11:23AM +0200, Ulf Hansson wrote:
> On 27 March 2014 16:25, Harini Katakam <harinik@...inx.com> wrote:
[...]
> > +static int __maybe_unused zynq_gpio_runtime_suspend(struct device *dev)
> > +{
> > +       struct platform_device *pdev = to_platform_device(dev);
> > +       struct zynq_gpio *gpio = platform_get_drvdata(pdev);
> > +
> > +       clk_disable(gpio->clk);
> 
> You should be able can use clk_disable_unprepare() here.
> 
> > +
> > +       return 0;
> > +}
> > +
> > +static int __maybe_unused zynq_gpio_runtime_resume(struct device *dev)
> > +{
> > +       struct platform_device *pdev = to_platform_device(dev);
> > +       struct zynq_gpio *gpio = platform_get_drvdata(pdev);
> > +
> > +       return clk_enable(gpio->clk);
> 
> You should be able can use clk_prepare_enable() here.

Is there some common practice regarding this? As I understand it, we
want to ensure the clock to be gated during suspend, which should happen
with clk_disable(). Why would we also unprepare the clock? We are highly
likely to use it again once we resume.

	Thanks,
	Sören


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