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Message-ID: <20220110201014.mtajyrfcfznfhyqm@pengutronix.de>
Date: Mon, 10 Jan 2022 21:10:14 +0100
From: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To: Sergey Shtylyov <s.shtylyov@....ru>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
linux-kernel@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
Ulf Hansson <ulf.hansson@...aro.org>,
Vignesh Raghavendra <vigneshr@...com>,
Jiri Slaby <jirislaby@...nel.org>,
Liam Girdwood <lgirdwood@...il.com>, linux-iio@...r.kernel.org,
Linus Walleij <linus.walleij@...aro.org>,
Amit Kucheria <amitk@...nel.org>, alsa-devel@...a-project.org,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
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Brian Norris <computersforpeace@...il.com>,
"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH 1/2] platform: make platform_get_irq_optional() optional
Hello,
On Mon, Jan 10, 2022 at 10:54:48PM +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...
The difference to gpiod_get_optional (and most other *_optional) is that
you can use the NULL value as if it were a valid GPIO.
As this isn't given with for irqs, I don't think changing the return
value has much sense. In my eyes the problem with platform_get_irq() and
platform_get_irq_optional() is that someone considered it was a good
idea that a global function emits an error message. The problem is,
that's only true most of the time. (Sometimes the caller can handle an
error (here: the absence of an irq) just fine, sometimes the generic
error message just isn't as good as a message by the caller could be.
(here: The caller could emit "TX irq not found" which is a much nicer
message than "IRQ index 5 not found".)
My suggestion would be to keep the return value of
platform_get_irq_optional() as is, but rename it to
platform_get_irq_silent() to get rid of the expectation invoked by the
naming similarity that motivated you to change
platform_get_irq_optional().
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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