Re: [PATCH v1 04/11] usb: phy: tegra: switch to using devm_gpiod_get()

On Mon, Sep 05, 2022 at 03:07:48PM -0700, Guenter Roeck wrote:

On 9/5/22 12:55, Andy Shevchenko wrote:

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On Mon, Sep 5, 2022 at 10:51 PM Dmitry Torokhov
[off-list ref] wrote:

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On Mon, Sep 05, 2022 at 10:41:40PM +0300, Andy Shevchenko wrote:

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On Mon, Sep 5, 2022 at 10:40 PM Dmitry Torokhov
[off-list ref] wrote:

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On Mon, Sep 05, 2022 at 01:59:44PM +0300, Andy Shevchenko wrote:

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On Mon, Sep 5, 2022 at 9:32 AM Dmitry Torokhov
[off-list ref] wrote:

...

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+               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?

PTR_ERR_OR_ZERO() converts into an error code (if the pointer is an
ERR_PTR) or 0 if it is a real pointer. Its purpose is not to convert
NULL into 0, its purpose is to convert a pointer either into an error
code or 0. That is what is done here, and it is done all over the place
in the kernel. I don't see your problem with it. Care to explain ?

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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.

You lost me. Really, please explain your problem with PTR_ERR_OR_ZERO().

I don't know what I was thinking about... You, guys, are right, sorry for
my noise.

-- 
With Best Regards,
Andy Shevchenko



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