On 12/10/21 2:28 PM, Andy Shevchenko wrote: >>>>>>>>> While at it, drop redundant check for 0 as platform_get_irq() spills >>>>>>>>> out a big WARN() in such case. >>>>>>>> >>>>>>>> And? IRQ0 is still returned! :-( >>>>>>> >>>>>>> It should not be returned in the first place. >>>>>> >>>>>> But it still is, despite the WARN(), right? >>>>> >>>>> So, you admit that there is a code which does that? >>>> >>>> I admit *what*?! That platfrom_get_irq() and its ilk return IRQ0 while they >>>> shouldn't? =) >>> >>> That there is a code beneath platform_get_irq() that returns 0, yes. >> >> Look at the ACPI-specific GpioInt handling code (just above the out_not_found label) -- >> I'm not sure the check there is correct -- I'm not very familiar with ACPI, you seem to >> know it much better. :-) > > And what is your point here exactly? You're saying IRQ0 shouldn't be returned (by the ACPI code) -- from this fragment we can see that it may be returned... > If == 0 case happens, it will be > immediately WARN() and reported (I hope) Well, "hope dies last"... :-) > since it will mean bug in the code. > >> Also, 0 can be specified via the normal IRQ resource. I know of e.g. the Alchemy MIPS SoCs >> that have IRQ0 used by UART0; luckily, currently SoC IRQs are mapped starting at Linux IRQ8 >> (but it wasn't the case in the 2.6.1x time frame where we had issue with the serial driver)... > > You mixed up HW IRQ with vIRQ. I didn't. Linux expects the vIRQs (I called them Linux IRQs). In the 2.6.1x time frame those corresponded 1:1 on Alchemy. Also, there's 8259 which is always mapped at vIRQ0 (or the legacy drivers won't work). > The former one may be 0 and it's completely valid case, while > the second one is not. Well, request_irq() happilly takes vIRQ0. Moreover, there are 8253 drivers in e.g. the arch/x86/ (PPC and MIPS too) which do use vIRQ0. >>>>> That code should be fixed first. Have you sent a patch? >>>> >>>> Which code?! You got me totally muddled. =) >>> >>> Above mentioned. >> >> What needs to be fixed in this case is the interrupt controller driver. > > What do you mean by that? You better ask Linus... ;-) > vIRQ is handled by IRQ core, IRQ controller driver > just a mere provider of the resource. And those exceptions for vIRQ == 0 > shouldn't be propagated to the platform code or so. >> Quoting Linus >> (imprecisely :-)), IRQ #s should be either mapped starting with #1 or IRQ0 remapped at >> the end of the controller's interrupt range... I currently have no information on the >> platforms requiring such kind of fixing (Alchemy don't seem to need it now)... Well, actually that Linus' quote predates drivers/irqchip/, so I must confess this argument was wrong... :-) > Again, do not mix vIRQ (about which Linus ranted) and HW IRQ. > > ... > >>>>>>>>> - if (!irq) >>>>>>>>> - return -EINVAL; >>>>>>>> >>>>>>>> This is prermature -- let's wait till my patch that stops returning IRQ0 from >>>>>>>> platform_get_irq() and friends gets merged.... >>>>>>> >>>>>>> What patch? >>>>>> >>>>>> https://marc.info/?l=linux-kernel&m=163623041902285 >>>>>> >>>>>>> Does it fix platform_get_irq_optional()? >>>>>> >>>>>> Of course! :-) >>>>> >>>>> Can you share link to lore.kernel.org, please? >>>>> It will make much easier to try and comment. >>>> >>>> I don't know how to uise it yet, and I'm a little busy with other IRQ0 issues ATM, > >> A little bit, I meant to type. > > No problem. I just haven't got what other IRQ0 issues except fixing > platform_get_irq_optional() et al. could be possibly needed... There is other IRQ0 issue which is very old already... [...] MBR, Sergey
