On Thursday 05 July 2012, Andrew Lunn wrote: > > > > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
