Subject: Re: [PATCH 1/2] platform: make platform_get_irq_optional() optional

From: Andrew Lunn <[email-masked]>
Date: Mon, 10 Jan 2022 22:18:14 +0100

On Mon, Jan 10, 2022 at 09:10:14PM +0100, Uwe Kleine-König wrote:
> 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/[email-masked]/
> > 
> > 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.

We actually want platform_get_irq_optional() to look different to all
the other _optional() methods because it is not equivalent. If it
looks the same, developers will assume it is the same, and get
themselves into trouble.

> 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().

This is a good idea.

     Andrew