On Mon, Jan 10, 2022 at 09:10:14PM +0100, Uwe Kleine-König wrote: > 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@xxxxxxxxxxxxxxx/ > > > > 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. The problem is not only there, but also in the platform_get_irq() and that problem is called vIRQ0. Or as Linus put it "_cookie_" for IRQ, which never ever should be 0. > 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(). This won't fix the issue with vIRQ0. -- With Best Regards, Andy Shevchenko
