On Thu, Oct 06, 2022 at 02:01:57PM +0000, Christophe Leroy wrote: > > > Le 06/10/2022 à 15:50, Alan Stern a écrit : > > On Thu, Oct 06, 2022 at 07:15:44AM +0200, Christophe Leroy wrote: > >> NO_IRQ is used to check the return of irq_of_parse_and_map(). > >> > >> On some architecture NO_IRQ is 0, on other architectures it is -1. > >> > >> irq_of_parse_and_map() returns 0 on error, independent of NO_IRQ. > > > > This isn't clear. Does absence of an irq count as an error? In other > > words, will irq_of_parse_and_map() sometimes return 0 and other times > > return NO_IRQ? What about architectures on which 0 is a valid irq > > number? > > NO_IRQ doesn't exist anywhere in core functions. Only some drivers and > some architectures have relics of it. > > irq_of_parse_and_map() will always return 0 on error. > > 0 can't be a valid logical IRQ number. It may only be a valid hwirq > number but it will always be translated to a non-zero logical irq number. > > I'm trying to get rid of NO_IRQ completely in powerpc code, therefore > trying to clean-up all drivers used by powerpc architecture. > > Long time ago Linus advocated for not using NO_IRQ, see > https://lkml.org/lkml/2005/11/21/221 Okay, good. Please resubmit the patch and include some of these things in the patch description. Alan Stern
