linux-kernel - Re: [PATCH v1 06/11] PCI: aardvark: switch to using devm_gpiod_get

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Date:   Tue, 6 Sep 2022 01:10:10 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Matti Vaittinen <mazziesaccount@...il.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Felipe Balbi <balbi@...nel.org>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Daniel Vetter <daniel@...ll.ch>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Marc Zyngier <maz@...nel.org>,
        Richard Weinberger <richard@....at>,
        David Airlie <airlied@...ux.ie>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Rob Herring <robh@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-watchdog@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v1 06/11] PCI: aardvark: switch to using
 devm_gpiod_get_optional()

On Monday 05 September 2022 15:54:53 Dmitry Torokhov wrote:
> On Mon, Sep 05, 2022 at 09:00:46AM +0200, Pali Rohár wrote:
> > On Sunday 04 September 2022 23:30:58 Dmitry Torokhov wrote:
> > > I would like to stop exporting OF-specific devm_gpiod_get_from_of_node()
> > > so that gpiolib can be cleaned a bit, so let's switch to the generic
> > > device property API.
> > > 
> > > I believe that the only reason the driver, instead of the standard
> > > devm_gpiod_get_optional(), used devm_gpiod_get_from_of_node() is
> > > because it wanted to set up a pretty consumer name for the GPIO,
> > 
> > IIRC consumer name is not used at all.
> > 
> > The reason was to specify full name of DTS property, for easier
> > identification of the code. DTS property is "reset-gpios" but API
> > specify only "reset".
> 
> I see. Do you want me to reset the patch with updated desctiption as to
> the reason devm_gpiod_get_from_of_node() was used?

I think it is fine. So add my:

Acked-by: Pali Rohár <pali@...nel.org>

Anyway as another improvement for future I would suggest some API
function with _optional_ logic, so it could be used for more PCIe
controller drivers (e.g. also tegra) without need to reimplement
-ENOENT handling. It is really strange if for acquiring same PERST#
line via GPIO ("reset-gpios" DT property) are used more API functions
in different PCIe drivers.

> > 
> > > and we now have a special API for that.
> > > 
> > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> > > 
> > > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> > > index 4834198cc86b..4a8a4a8522cb 100644
> > > --- a/drivers/pci/controller/pci-aardvark.c
> > > +++ b/drivers/pci/controller/pci-aardvark.c
> > > @@ -1856,20 +1856,19 @@ static int advk_pcie_probe(struct platform_device *pdev)
> > >  		return ret;
> > >  	}
> > >  
> > > -	pcie->reset_gpio = devm_gpiod_get_from_of_node(dev, dev->of_node,
> > > -						       "reset-gpios", 0,
> > > -						       GPIOD_OUT_LOW,
> > > -						       "pcie1-reset");
> > > +	pcie->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
> > >  	ret = PTR_ERR_OR_ZERO(pcie->reset_gpio);
> > >  	if (ret) {
> > > -		if (ret == -ENOENT) {
> > > -			pcie->reset_gpio = NULL;
> > > -		} else {
> > > -			if (ret != -EPROBE_DEFER)
> > > -				dev_err(dev, "Failed to get reset-gpio: %i\n",
> > > -					ret);
> > > -			return ret;
> > > -		}
> > > +		if (ret != -EPROBE_DEFER)
> > > +			dev_err(dev, "Failed to get reset-gpio: %i\n",
> > > +				ret);
> > > +		return ret;
> > > +	}
> > > +
> > > +	ret = gpiod_set_consumer_name(pcie->reset_gpio, "pcie1-reset");
> > > +	if (ret) {
> > > +		dev_err(dev, "Failed to set reset gpio name: %d\n", ret);
> > > +		return ret;
> > >  	}
> > >  
> > >  	ret = of_pci_get_max_link_speed(dev->of_node);
> > > 
> > > -- 
> > > b4 0.10.0-dev-fc921
> 
> Thanks.
> 
> -- 
> Dmitry