linux-kernel - Re: [PATCH 2/2] gpio: omap: save two lines by using devm_clk_get

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Message-ID: <af9d1d0a28b4f2c6a341f45f7f5e29247deb47e7.camel@siemens.com>
Date: Mon, 16 Dec 2024 11:27:11 +0000
From: "Sverdlin, Alexander" <alexander.sverdlin@...mens.com>
To: "mazziesaccount@...il.com" <mazziesaccount@...il.com>, "brgl@...ev.pl"
	<brgl@...ev.pl>
CC: "bartosz.golaszewski@...aro.org" <bartosz.golaszewski@...aro.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>
Subject: Re: [PATCH 2/2] gpio: omap: save two lines by using
 devm_clk_get_prepared()

Thanks for quick re-test Matti!

On Mon, 2024-12-16 at 13:11 +0200, Matti Vaittinen wrote:
> > > > > > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> > > > > > 
> > > > > > We can drop the else branch if we get the clock already prepared using
> > > > > > the relevant helper.
> > > > > > 
> > > > > > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> > > > > > ---
> > > > > 
> > > > > Booting a beaglebone black with the linux-next from Today fails
> > > > > (next-20241213). Enabling earlycon + debug yields below splat to be
> > > > > printed to the console:
> > > > > 
> > 
> > No problem! Thanks for the logs! I think I know what happened: I suppose
> > it's "prepared" counter underflow on probe deferral of GPIO driver
> > (there are "probe of 44e07000.gpio returned 517" visible).
> 
> Ah. Indeed. The deferral is visible in the logs.
> 
> > 
> > If you'd still have a chance to test 6.13.0-rc2-next-20241213,
> > I believe this was missing in the
> > "gpio: omap: save two lines by using devm_clk_get_prepared()":
> > 
> > diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
> > index 76d5d87e9681..0c30013d2b48 100644
> > --- a/drivers/gpio/gpio-omap.c
> > +++ b/drivers/gpio/gpio-omap.c
> > @@ -1473,8 +1473,6 @@ static int omap_gpio_probe(struct platform_device *pdev)
> >    	if (ret) {
> >    		pm_runtime_put_sync(dev);
> >    		pm_runtime_disable(dev);
> > -		if (bank->dbck_flag)
> > -			clk_unprepare(bank->dbck);
> >    		return ret;
> >    	}
> >    
> > @@ -1495,8 +1493,6 @@ static void omap_gpio_remove(struct platform_device *pdev)
> >    	cpu_pm_unregister_notifier(&bank->nb);
> >    	gpiochip_remove(&bank->chip);
> >    	pm_runtime_disable(&pdev->dev);
> > -	if (bank->dbck_flag)
> > -		clk_unprepare(bank->dbck);
> >    }
> >    
> >    static int __maybe_unused omap_gpio_runtime_suspend(struct device *dev)
> > 
> 
> This fixes the boot as you assumed.
> I suppose this should be baked in the Bartosz's original patch assumed 
> it was dropped from the GPIO tree.

Yes, this meant to be a "fixup!"...

> Furthermore, this seems to be a fix to a hidden problem on original 
> code. If the original code failed in the clk_prepare() and then deferred 
> probe(), this same problem should have appeared, right?
> 
> Maybe consider using Fixes - tag even if this and the original change 

It could be
Fixes: 5d9452e7c52a ("gpio: omap: fix clk_prepare/unprepare usage")
let's see what Bartosz says on this...

> got squashed. Feel free to add a:
> 
> Tested-By: Matti Vaittinen <mazziesaccount@...il.com>
> 
> if this fix goes to the tree "as is".

-- 
Alexander Sverdlin
Siemens AG
www.siemens.com