On 2021/12/13 20:52, Andy Shevchenko wrote: > 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. Sounds like a good plan to me. In the mean time though, your patch 1/2 should keep the "if (!irq)" test and return an error for that case. No ? -- Damien Le Moal Western Digital Research
