linux-kernel - Re: [PATCH v1 04/11] usb: phy: tegra: switch to using devm_gpiod

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Message-ID: <CAHp75VeNajcf-Y6xvDDVwZijg6U53ggg1HQox1AZ74=wRut+1Q@mail.gmail.com>
Date:   Mon, 5 Sep 2022 22:55:30 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
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>,
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Subject: Re: [PATCH v1 04/11] usb: phy: tegra: switch to using devm_gpiod_get()

On Mon, Sep 5, 2022 at 10:51 PM Dmitry Torokhov
<dmitry.torokhov@...il.com> wrote:
> On Mon, Sep 05, 2022 at 10:41:40PM +0300, Andy Shevchenko wrote:
> > On Mon, Sep 5, 2022 at 10:40 PM Dmitry Torokhov
> > <dmitry.torokhov@...il.com> wrote:
> > > On Mon, Sep 05, 2022 at 01:59:44PM +0300, Andy Shevchenko wrote:
> > > > On Mon, Sep 5, 2022 at 9:32 AM Dmitry Torokhov
> > > > <dmitry.torokhov@...il.com> wrote:

...

> > > > > -               gpiod = devm_gpiod_get_from_of_node(&pdev->dev, np,
> > > > > -                                                   "nvidia,phy-reset-gpio",
> > > > > -                                                   0, GPIOD_OUT_HIGH,
> > > > > -                                                   "ulpi_phy_reset_b");
> > > > > +               gpiod = devm_gpiod_get(&pdev->dev, "nvidia,phy-reset",
> > > > > +                                      GPIOD_OUT_HIGH);
> > > > >                 err = PTR_ERR_OR_ZERO(gpiod);
> > > >
> > > > What does _OR_ZERO mean now?
> > >
> > > This converts a pointer to an error code if a pointer represents
> > > ERR_PTR() encoded error, or 0 to indicate success.
> >
> > Yes, I know that. My point is, how is it useful now (or even before)?
> > I mean that devm_gpio_get() never returns NULL, right?
>
> What does returning NULL have to do with anything.

It has to do with a dead code. If defm_gpiod_get() does not return
NULL, then why do we even bother to check?

> It converts a pointer
> to a "classic" return code, with negative errors and 0 on success.
>
> It allows to not use multiple IS_ERR/PTR_ERR in the code (I'd need 1
> IS_ERR and 2 PTR_ERR, one in dev_err() and another to return).

I don't see how this is relevant.

-- 
With Best Regards,
Andy Shevchenko