2016-04-30 13:32 GMT+02:00 Linus Walleij <linus.wall...@linaro.org>: > On Fri, Apr 29, 2016 at 1:19 PM, Maxime Coquelin > <mcoquelin.st...@gmail.com> wrote: >> It looks like this: http://pastebin.com/raw/cs2WiNKZ >> You can directly check section 12.2.5 of the stm32f429 reference manual: >> http://www2.st.com/resource/en/reference_manual/dm00031020.pdf > > Nice ASCII art, include that into the commit message :)
I will! :) > >> For example, we can imagine a board where gpioa0 is used SD's card detect, >> and gpiob0 used to control a led. >> >> If we set the mux at request time, gpiob0 request may overwrite the mux >> configuration set by gpioa0, whereas it is not used as interrupt. >> >> That is the reason why I did it in .to_irq(). > > Well now I am even *more* convinced that this should not happen in > .to_irq(). .to_irq() should not do *anything*. > > This needs to happen as part of the irqchip setting up the actual > interrupt. > > And it seems the problem is that this driver does *not* define its > own irqchip, but it *should*. > > What you want to do is implement an hierarchical irqdomain in your > irqchip, which is what other drivers of this type are doing, see: > drivers/gpio/gpio-xgene-sb.c > irq_domain_create_hierarchy() is your friend. > >>> It should *also* be done in the set-up path for the irqchip >>> side, if that line is used without any interaction with the >>> gpio side of things. >> >> Actually, a line is either used by a GPIO, (exclusive) or another purpose. >> In the case of a GPIO line, I think we should always go through the gpio. > > This is a textbook example of a hierarchichal irq domain I think. > >>> The point is that each IRQ that ever get used >>> has a 1-to-1 relationship to a certain GPIO line, and if that >>> relationship cannot be resolved from the irqchip side, >>> something is wrong. The irqchip needs to enable the >>> GPIO line it is backing to recieve interrupts without any >>> requirements that .to_irq() have been called first. >> >> Actually, this is not a 1:1 relationship, as for example, exti0 can be >> connected >> to either gpioa0, or gpiob0,..., or gpiok0. > > That is what hierarchical irqdomain is for. > > You should expose an irqchip from the gpio driver, that give you > unique irq translations for *all* GPIO lines. > > Then, at runtime, if the hierarchical irqdomain cannot map > (i.e. mux) the interrupt onto one of the available lines, > you will get an error. Thanks a lot for this valuable feedback. I will have a look at hierachical irq domains, and hope to come back this week with an implementation. Regards, Maxime
