linux-kernel - Re: [PATCH v2 1/2] platform: make platform_get_irq

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Message-ID: <20220214135618.kdiikxi3j4j4erks@pengutronix.de>
Date:   Mon, 14 Feb 2022 14:56:18 +0100
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Andrew Lunn <andrew@...n.ch>, Ulf Hansson <ulf.hansson@...aro.org>,
        Vignesh Raghavendra <vigneshr@...com>, kvm@...r.kernel.org,
        "Rafael J. Wysocki" <rafael@...nel.org>, linux-iio@...r.kernel.org,
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Subject: Re: [PATCH v2 1/2] platform: make platform_get_irq_optional()
 optional

Hello Andy,

On Mon, Feb 14, 2022 at 12:13:01PM +0200, Andy Shevchenko wrote:
> On Mon, Feb 14, 2022 at 08:13:51AM +0100, Uwe Kleine-König wrote:
> > On Sat, Feb 12, 2022 at 11:16:30PM +0300, Sergey Shtylyov wrote:
> > > This patch is based on the former Andy Shevchenko's patch:
> > > 
> > > https://lore.kernel.org/lkml/20210331144526.19439-1-andriy.shevchenko@linux.intel.com/
> > > 
> > > Currently platform_get_irq_optional() returns an error code even if IRQ
> > > resource simply has not been found.  It prevents the callers from being
> > > error code agnostic in their error handling:
> > > 
> > > 	ret = platform_get_irq_optional(...);
> > > 	if (ret < 0 && ret != -ENXIO)
> > > 		return ret; // respect deferred probe
> > > 	if (ret > 0)
> > > 		...we get an IRQ...
> > > 
> > > All other *_optional() APIs seem to return 0 or NULL in case an optional
> > > resource is not available.  Let's follow this good example, so that the
> > > callers would look like:
> > > 
> > > 	ret = platform_get_irq_optional(...);
> > > 	if (ret < 0)
> > > 		return ret;
> > > 	if (ret > 0)
> > > 		...we get an IRQ...
> > > 
> > > Reported-by: Matthias Schiffer <matthias.schiffer@...tq-group.com>
> > > Signed-off-by: Sergey Shtylyov <s.shtylyov@....ru>
> > 
> > While this patch is better than v1, I still don't like it for the
> > reasons discussed for v1. (i.e. 0 isn't usable as a dummy value which I
> > consider the real advantage for the other _get_optional() functions.)
> 
> I think you haven't reacted anyhow to my point that you mixing apples and
> bananas together when comparing this 0 to the others _optional APIs.

Is this a question to me or Sergey?

I fully agree, when the 0 of platform_get_irq_optional is an apple and
the NULL of gpio_get_optional is a banana, I doubt "All other
*_optional() APIs seem to return 0 or NULL in case an optional resource
is not available.  Let's follow this good example, [...]".

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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