Messages in this thread | | | From | Linus Walleij <> | Date | Tue, 25 Sep 2018 10:11:06 +0200 | Subject | Re: [PATCH 6/9] gpio: Add support for hierarchical IRQ domains |
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Hi Thierry!
Thanks for the patch!
I am a bit ignorant about irqdomains so I will probably need an ACK from some irq maintainer before I can apply this.
On Fri, Sep 21, 2018 at 12:25 PM Thierry Reding <thierry.reding@gmail.com> wrote:
> From: Thierry Reding <treding@nvidia.com> > > Hierarchical IRQ domains can be used to stack different IRQ controllers > on top of each other. One specific use-case where this can be useful is > if a power management controller has top-level controls for wakeup > interrupts. In such cases, the power management controller can be a > parent to other interrupt controllers and program additional registers > when an IRQ has its wake capability enabled or disabled. > > Signed-off-by: Thierry Reding <treding@nvidia.com>
While I think it is really important that we start supporting hierarchical irqdomains in the gpiolib core, I want a more complete approach, so that drivers that need hierarchical handling of irqdomains can get the same support from gpiolib as they get for simple domains.
> @@ -1918,7 +1918,9 @@ static int gpiochip_add_irqchip(struct gpio_chip *gpiochip, > type = IRQ_TYPE_NONE; > } > > - gpiochip->to_irq = gpiochip_to_irq; > + if (!gpiochip->to_irq) > + gpiochip->to_irq = gpiochip_to_irq;
So here you let the drivers override the .to_irq() function and that I think gets confusing as we are asking gpiolib to handle our irqchip.
> - gpiochip->irq.domain = irq_domain_add_simple(np, gpiochip->ngpio, > - gpiochip->irq.first, > - ops, gpiochip); > + if (gpiochip->irq.parent_domain) > + gpiochip->irq.domain = irq_domain_add_hierarchy(gpiochip->irq.parent_domain, > + 0, gpiochip->ngpio, > + np, ops, gpiochip); > + else > + gpiochip->irq.domain = irq_domain_add_simple(np, gpiochip->ngpio, > + gpiochip->irq.first, > + ops, gpiochip);
So this part is great: if we pass in a parent domain the core helps us create the hierarchy.
But the stuff in .to_irq() should also be handled in the gpiolib core: the irq_domain_alloc_irqs(domain, 1, NUMA_NO_NODE, &spec) for example. That way you should not need any external .to_irq() function.
I can't see if you need to pull more stuff into the core to accomplish that, but I think in essence the core gpiolib needs to be more helpful with hierarchies.
Yours, Linus Walleij
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