Re: [PATCH v2 01/12] ARM: Orion: DT support for IRQ and GPIO Controllers

On Thursday 05 July 2012, Andrew Lunn wrote:

quoted

I'm wondering about this one.  The other platforms usually put the secondary
interrupt controllers into the same match table, while you call orion_gpio_of_init
from orion_add_irq_domain. Can you explain why you do this? Does it have
any disadvantages?

The issue is knowing what IRQ number to use for the secondary
interrupts.

Orion use generic chip interrupts, both for the main interrupts and
the GPIO interrupts. This does not yet support irq domain, so i have
to layer a legacy domain on top. The legacy domain needs to know the
first IRQ and the number of IRQs. For the primary IRQs that is
easy. However, GPIO IRQ is not so easy, it depends on how many primary
IRQs there are. This is not fixed. Orion5x has 32, Dove 64, kirkwood,
64, and mv78xx0 has 96. I need to know this number when adding the
GPIO secondary IRQ legacy domain. By calling orion_gpio_of_init() in
the orion_add_irq_domain() i have this number to hand. If i used to
entries in the match table, i would have to put this number into some
global variable, or somehow ask the IRQ subsystem what the next free
IRQ number is.

But couldn't you store the number of interrupts for the primary controller
in a local variable? I think the of_irq code already guarantees that
the parent is probed first.

As for disadvantages, humm. Dove has yet more interrupts, from the
PMU. They are currently unsupported in DT. When we add support for the
PMU interrupt controller, we are going to have the same problem, what
IRQ base should it use. Either we extend the chaining, calling
dove_pmu_of_init from orion_gpio_of_init(), where we know the next
free IRQ. Or we find out how to ask the IRQ subsystem for the next
available. Better still, the work to make generic chip interrupts irq
domain aware would get completed, and we can swap all this code to irq
domain linear and this whole probable probably goes away.

Yes, that makes sense. Using the linear domain should solve all these
nicely.

	Arnd

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