linux-kernel - Re: [PATCH RFT 3/3] ARM: tegra: dts: seaboard: enable keyboard

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Message-ID: <20130111233615.GO23505@n2100.arm.linux.org.uk>
Date:	Fri, 11 Jan 2013 23:36:16 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Laxman Dewangan <ldewangan@...dia.com>,
	linux-tegra@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFT 3/3] ARM: tegra: dts: seaboard: enable keyboard

On Fri, Jan 11, 2013 at 04:27:07PM -0700, Stephen Warren wrote:
> On 01/11/2013 04:24 PM, Russell King - ARM Linux wrote:
> > On Fri, Jan 11, 2013 at 04:09:59PM -0700, Stephen Warren wrote:
> >> On 01/11/2013 06:33 AM, Laxman Dewangan wrote:
> >>> 	kbc->clk = clk_get(&pdev->dev, NULL);
> >>> 	if (IS_ERR(kbc->clk)) {
> >>> 		dev_err(&pdev->dev, "failed to get keyboard clock\n");
> >>> 		err = PTR_ERR(kbc->clk);
> >>> 		goto err_iounmap;
> >>> 	}
> >>
> >> Should that check be if (!kbc-clk) instead? Or does the common clock
> >> framework require if (IS_ERR_OR_NULL(kbc->clk)); hopefully not since
> >> IS_ERR_OR_NULL shouldn't be used any more.
> > 
> > /**
> >  * clk_get - lookup and obtain a reference to a clock producer.
> >  * @dev: device for clock "consumer"
> >  * @id: clock consumer ID
> >  *
> >  * Returns a struct clk corresponding to the clock producer, or
> >    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> >  * valid IS_ERR() condition containing errno.  ...
> >    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > 
> > Or, put another way:
> > 
> > 	If (!IS_ERR(clk))
> > 		The_Clock_Is_Valid();
> > 	Else
> > 		The_Clock_Is_Invalid();
> > 		The_Error = PTR_ERR(clk);
> 
> OK, but that doesn't appear to be what happened in practice.

It's what I've been saying each time I see an abuse, the problem is
people don't care to read the documentation provided let alone
understand the interfaces.

That's precisely why IS_ERR_OR_NULL() is to be removed.  One less
thing for someone to throw a dart at as a selection method to use.
Or maybe roll a dice.  Or whatever way they do seem to choose.
(Whatever that is, it's not based on any sound engineering practice
I can make out.)
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