linux-kernel - Re: [PATCH v3] PCI: imx6: Replace legacy gpio interface for gpiod interface

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Message-ID: <56052bc6e3b6cab6bfdfc5f706ec9984bea16bba.camel@pengutronix.de>
Date:   Mon, 25 Apr 2022 14:07:53 +0200
From:   Lucas Stach <l.stach@...gutronix.de>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Maíra Canal <maira.canal@....br>
Cc:     hongxing.zhu@....com, lorenzo.pieralisi@....com, robh@...nel.org,
        bhelgaas@...gle.com, helgaas@...nel.org, shawnguo@...nel.org,
        s.hauer@...gutronix.de, kernel@...gutronix.de, linux-imx@....com,
        linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] PCI: imx6: Replace legacy gpio interface for gpiod
 interface

Hi Linus,

Am Donnerstag, dem 21.04.2022 um 01:24 +0200 schrieb Linus Walleij:
> Hi Maira and sorry for being slow on reviews.
> 
> On Tue, Nov 2, 2021 at 2:04 AM Maíra Canal <maira.canal@....br> wrote:
> 
> > -               gpio_set_value_cansleep(imx6_pcie->reset_gpio,
> > +               gpiod_set_raw_value_cansleep(imx6_pcie->reset_gpio,
> >                                         !imx6_pcie->gpio_active_high);
> 
> Hm I see you got advised to use the raw api. I'm not so sure about
> that I like v1 better.
> 
> > +       imx6_pcie->reset_gpio = devm_gpiod_get_optional(dev, "reset",
> > +                       imx6_pcie->gpio_active_high ?  GPIOD_OUT_HIGH : GPIOD_OUT_LOW);
> > +       if (IS_ERR(imx6_pcie->reset_gpio))
> > +               return dev_err_probe(dev, PTR_ERR(imx6_pcie->reset_gpio),
> > +                               "unable to get reset gpio\n");
> 
> Where is this descriptor coming from? Device trees? Can't we just fix the
> DTS file(s) in that case given how wrong they are if they don't set
> GPIO_ACTIVE_LOW flag on this IRQ.

The binding explicitly describes the GPIO as not polarity aware and has
a separate property "reset-gpio-active-high" to avoid breaking old
DTBs. I don't think it's helpful to dismiss this explicit backward
compat just because the driver code looks nicer that way.

Regards,
Lucas