linux-kernel - Re: [PATCH v1 01/11] PCI: tegra: switch to using devm_fwnode_gpiod

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Message-ID: <YxZ9BkBnQOUpXt/O@google.com>
Date:   Mon, 5 Sep 2022 15:49:42 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Pali Rohár <pali@...nel.org>
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 01/11] PCI: tegra: switch to using
 devm_fwnode_gpiod_get

On Mon, Sep 05, 2022 at 09:19:02AM +0200, Pali Rohár wrote:
> On Sunday 04 September 2022 23:30:53 Dmitry Torokhov wrote:
> > I would like to limit (or maybe even remove) use of
> > [devm_]gpiod_get_from_of_node in drivers so that gpiolib can be cleaned
> > a bit, so let's switch to the generic device property API. It may even
> > help with handling secondary fwnodes when gpiolib is taught to handle
> > gpios described by swnodes.
> > 
> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> > 
> > diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c
> > index 8e323e93be91..929f9363e94b 100644
> > --- a/drivers/pci/controller/pci-tegra.c
> > +++ b/drivers/pci/controller/pci-tegra.c
> > @@ -2202,10 +2202,11 @@ static int tegra_pcie_parse_dt(struct tegra_pcie *pcie)
> >  		 * and in this case fall back to using AFI per port register
> >  		 * to toggle PERST# SFIO line.
> >  		 */
> > -		rp->reset_gpio = devm_gpiod_get_from_of_node(dev, port,
> > -							     "reset-gpios", 0,
> > -							     GPIOD_OUT_LOW,
> > -							     label);
> > +		rp->reset_gpio = devm_fwnode_gpiod_get(dev,
> > +						       of_fwnode_handle(port),
> > +						       "reset",
> > +						       GPIOD_OUT_LOW,
> > +						       label);
> 
> Why in pci-aardvark.c for PERST# reset-gpio you have used
> devm_gpiod_get_optional() and here in pci-tegra.c you have used
> devm_fwnode_gpiod_get()? I think that PERST# logic is same in both
> drivers.

I believe Andy already answered that, but in this driver we can have
several root ports described via subnodes of dev->of_node, and reset
GPIOs are attached to those subnodes. We are forced to use
devm_fwnode_gpiod_get() instead of devm_gpiod_get_optional() as we need
to supply the exact fwnode we need to look up GPIO in, and can not infer
it from the 'dev' parameter of devm_gpiod_get().

Thanks.

-- 
Dmitry