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

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Date:   Mon, 5 Sep 2022 16:18:44 -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 06/11] PCI: aardvark: switch to using
 devm_gpiod_get_optional()

On Tue, Sep 06, 2022 at 01:10:10AM +0200, Pali Rohár wrote:
> 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

I think we need to see how many are attaching reset lines to subnodes.
If there are multiple then I agree we could add _optional. So far I see:

dtor@...r-ws:~/kernel/linux-next (gpiod_get_from_of_node-remove)$ git grep '"reset"' -- drivers/pci/controller/
drivers/pci/controller/cadence/pci-j721e.c:             gpiod = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
drivers/pci/controller/dwc/pci-keystone.c:      gpiod = devm_gpiod_get_optional(dev, "reset",
drivers/pci/controller/dwc/pci-meson.c: mp->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
drivers/pci/controller/dwc/pcie-dw-rockchip.c:  rockchip->rst_gpio = devm_gpiod_get_optional(&pdev->dev, "reset",
drivers/pci/controller/dwc/pcie-fu740.c:        afp->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
drivers/pci/controller/dwc/pcie-intel-gw.c:     pcie->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
drivers/pci/controller/dwc/pcie-keembay.c:      pcie->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
drivers/pci/controller/dwc/pcie-qcom-ep.c:      pcie_ep->reset = devm_gpiod_get(dev, "reset", GPIOD_IN);
drivers/pci/controller/dwc/pcie-tegra194.c:     pcie->pex_rst_gpiod = devm_gpiod_get(pcie->dev, "reset", GPIOD_IN);
drivers/pci/controller/pci-aardvark.c:  pcie->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
drivers/pci/controller/pci-tegra.c:                                                    "reset",
drivers/pci/controller/pcie-apple.c:                                   "reset", 0, GPIOD_OUT_LOW, "PERST#");
drivers/pci/controller/pcie-mt7621.c:   port->gpio_rst = devm_gpiod_get_index_optional(dev, "reset", slot,

So majority have reset lines attached to the "main" node and thus can use
devm_gpiod_get_optional().

Thanks.

-- 
Dmitry