linux-kernel - Re: [PATCH RFT 1/2] phylib: add device reset GPIO support

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Date:	Mon, 30 May 2016 16:57:19 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
Cc:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Frank Rowand <frowand.list@...il.com>,
	Paweł Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFT 1/2] phylib: add device reset GPIO support

On Thu, May 26, 2016 at 9:00 PM, Uwe Kleine-König
<u.kleine-koenig@...gutronix.de> wrote:
> On Thu, May 26, 2016 at 11:00:55AM +0200, Linus Walleij wrote:
>> On Thu, May 12, 2016 at 8:42 PM, Uwe Kleine-König
>> <u.kleine-koenig@...gutronix.de> wrote:
>>
>> > [added Linus Walleij to Cc, there is a question for you/him below]
>> (...)
>> >> +void mdio_device_reset(struct mdio_device *mdiodev, int value)
>> >> +{
>> >> +     if (mdiodev->reset)
>> >> +             gpiod_set_value(mdiodev->reset, value);
>> >
>> > Before v4.6-rc1~108^2~91 it was not necessary to check for the first
>> > parameter being non-NULL before calling gpiod_set_value. Linus, did you
>> > change this on purpose?
>>
>> Not really. And AFAICT it is still not necessary: what changed is that
>> an error message will be printed by VALIDATE_DESC() if you do that.
>> And that is proper I guess? I think it's sloppy code to randomly pass in
>> NULL to a call and just expect it to bail out, it seems more like
>> exercising the error path than something you'd normally rely on.
>>
>> Or am I getting things wrong?
>
> is the following sloppy?:
>
>         somegpio = gpiod_get_optional(dev, "some", GPIOD_OUT_LOW);
>         if (IS_ERR(somegpio))
>                 return PTR_ERR(somegpio);
>         gpiod_set_value(somegpio, 1);

Grrr OK I see, it's explicit from the _optional() call that it may be NULL
and then it should be ignored. So subsequent functions should ignore
that and bail out. My bad, sorry.

> If not (as I assume) you really changed something as this might trigger
> the warning.

Making a patch.

Yours,
Linus Walleij