Messages in this thread | | | Date | Sat, 03 Aug 2019 10:12:49 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH 3/5] MIPS: lantiq: add an irq_domain and irq_chip for EBU |
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Hi Martin,
On Thu, 01 Aug 2019 18:42:42 +0100, Martin Blumenstingl <martin.blumenstingl@googlemail.com> wrote:
[...]
> > > +static void ltq_ebu_irq_handler(struct irq_desc *desc) > > > +{ > > > + struct irq_domain *domain = irq_desc_get_handler_data(desc); > > > + struct irq_chip *irqchip = irq_desc_get_chip(desc); > > > + > > > + chained_irq_enter(irqchip, desc); > > > + > > > + generic_handle_irq(irq_find_mapping(domain, 0)); > > > > Having an irqdomain for a single interrupt is a bit over the top... Is > > that for the convenience of the DT infrastructure? > yes, I did it to get DT support > please let me know if there's a "better" way (preferably with another > driver as example)
To be honest, the chained handler is what troubles me the most. You normally would use such a construct if you had a multiplexer. In your case, you have a 1:1 relationship between input and output. It is just that this irqchip allows the trigger to be adapted, which normally calls for a hierarchical implementation.
In your case, with only a single interrupt, it doesn't matter much though.
> > [...] > > > + irq_create_mapping(domain, 0); > > > > Why do you need to perform this eagerly? I'd expect this interrupt to > > be mapped when it is actually claimed by a driver. > I don't remember why I added it, it may be left-over from copying from > another driver > in v2 I'll try to drop it > > > > + > > > + irq_set_chained_handler_and_data(irq, ltq_ebu_irq_handler, domain); > > > > And there is no HW initialisation whatsoever? I'd expect, at the very > > least, the sole interrupt to be configured as disabled/masked. > I can add that. is there any "best practice" on what I should > initialize (just disable it or also set a "default" mode like > LEVEL_LOW)?
Whichever default state makes sense. What you want to avoid is to boot the kernel with a screaming interrupt because some firmware has left it enabled.
Thanks,
M.
-- Jazz is not dead, it just smells funny.
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