Re: [PATCH RFC 2/6] gpio: mvebu: honour EPROBE_DEFER for devm_clk_get() - Russell King

From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>, Andrew Lunn <andrew@lunn.ch>,
	Jason Cooper <jason@lakedaemon.net>,
	devicetree@vger.kernel.org,
	Linus Walleij <linus.walleij@linaro.org>,
	linux-pwm@vger.kernel.org,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Rob Herring <robh+dt@kernel.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	linux-gpio@vger.kernel.org,
	Gregory Clement <gregory.clement@bootlin.com>,
	linux-arm-kernel@lists.infradead.org,
	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Subject: Re: [PATCH RFC 2/6] gpio: mvebu: honour EPROBE_DEFER for devm_clk_get()
Date: Sun, 29 Mar 2020 14:34:00 +0100	[thread overview]
Message-ID: <20200329133400.GA25745@shell.armlinux.org.uk> (raw)
In-Reply-To: <20200329131659.4hbshjst4ccvje2n@pengutronix.de>

On Sun, Mar 29, 2020 at 03:16:59PM +0200, Uwe Kleine-König wrote:
> On Sun, Mar 29, 2020 at 11:48:09AM +0100, Russell King wrote:
> > Honour deferred probing for devm_clk_get() so that we can get the clock
> > for PWM.
> > 
> > Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
> > ---
> >  drivers/gpio/gpio-mvebu.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
> > index fa5641615db6..ee13b11c5298 100644
> > --- a/drivers/gpio/gpio-mvebu.c
> > +++ b/drivers/gpio/gpio-mvebu.c
> > @@ -1132,6 +1132,9 @@ static int mvebu_gpio_probe(struct platform_device *pdev)
> >  	}
> >  
> >  	mvchip->clk = devm_clk_get(&pdev->dev, NULL);
> > +	if (mvchip->clk == ERR_PTR(-EPROBE_DEFER))
> > +		return -EPROBE_DEFER;
> > +
> >  	/* Not all SoCs require a clock.*/
> >  	if (!IS_ERR(mvchip->clk))
> >  		clk_prepare_enable(mvchip->clk);
> 
> I'd say the following is the right thing to do here:
> 
> 	mvchip->clk = devm_clk_get_optional(...);
> 	if (IS_ERR(mvchip->clk))
> 		return ...

It's not that simple.  The clock is required for Armada 370, and is
optional for Armada 8040.

-- 
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