On Mon, Dec 13, 2021 at 07:39:31AM +0900, Damien Le Moal wrote: > On 2021/12/11 19:25, Sergey Shtylyov wrote: > > On 11.12.2021 2:45, Damien Le Moal wrote: ... > >>>> So 0 will be returned as-is. That is rather weird. That should be fixed to > >>>> return -ENXIO: > >>>> > >>>> if (WARN(ret == 0, "0 is an invalid IRQ number\n")) > >>>> return -ENXIO; > >>>> return ret; > >>> > >>> My unmerged patch (https://marc.info/?l=linux-kernel&m=163623041902285) does this > >>> but returns -EINVAL instead. > >> > >> Thinking more about this, shouldn't this change go into platform_get_irq() > >> instead of platform_get_irq_optional() ? > > > > Why? platform_get_irq() currently just calls platform_get_irq_optional()... > > > >> The way I see it, I think that the intended behavior for > >> platform_get_irq_optional() is: > >> 1) If have IRQ, return it, always > 0 > >> 2) If no IRQ, return 0 > > > > That does include the IRQ0 case, right? > > IRQ 0 being invalid, I think that case should be dealt with internally within > platform_get_irq_optional() and warn/error return. IRQ 0 showing up would thus > be case (3), an error. > > > > >> 3) If error, return < 0 > >> no ? > > > > I completely agree, I (after thinking a bit) have no issues with that... > > > >> And for platform_get_irq(), case (2) becomes an error. > >> Is this the intended semantic ? > > > > I don't see how it's different from the current behavior. But we can do > > that as well, I just don't see whether it's really better... > > The problem I see is that the current behavior is unclear: what does > platform_get_irq_optional() returning 0 mean ? IRQ == 0 ? or "no IRQ" ? I think > it should be the latter rather than the former. Note that the function could > return ENOENT (or similar) for the "no IRQ" case. With that, case (2) goes away, > but then I do not see any difference between platform_get_irq_optional() and > platform_get_irq(). > > If the preferred API semantic is to allow returning IRQ 0 with a warning, then > the kdoc comments of platform_get_irq_optional() and platform_get_irq() are > totally broken, and the code for many drivers is probably wrong too. Yeah, what we need to do is that (roughly a roadmap): - revisit callers of platform_get_irq_optional() to be prepared for new behaviour - rewrite platform_get_irq() to return -ENOENT - rewrite platform_get_irq_optional() to return 0 on -ENOENT This is how other similar (i.e. _optional) APIs do. -- With Best Regards, Andy Shevchenko
