[PATCH 1/2] pinctrl: meson: Enable GPIO IRQs

[Carlo Caione]

On Wed, Jun 17, 2015 at 10:26 AM, Linus Walleij
<linus.walleij at linaro.org> wrote:
> On Sat, Jun 13, 2015 at 5:35 PM, Carlo Caione <carlo at caione.org> wrote:
>> On Mon, Jun 1, 2015 at 4:30 PM, Linus Walleij <linus.walleij at linaro.org> wrote:
...
>> Ok, it sounds reasonable but this implies that the mapping between the
>> virq and the hwirq in the outermost domain already exists when the
>> .to_irq hook is called, right? Also IIUC for hierarchical domains the
>> mapping should also exist on all the irq_domains in the hierarchy.
>
> I guess, I am no expert in the hierarchical domains, sadly.
>
> The point is that it should be possible to request an IRQ
> from the irqchip side without having to have called .to_irq()
> on the GPIO first.

Ok. Let me rephrase that to be sure we are on the same track. It
should be possible to request an IRQ without having to have called
.to_irq() on the GPIO first to allocate the IRQ descriptor.
Ok but when is this the case? If our IRQ line is in the DT, then
irq_create_of_mapping() takes care of allocating the descriptor. Now,
the only other case I know of is for MMC/slot-gpio. In this case
mmc_gpiod_request_cd_irq() only calls .to_irq() before requesting the
IRQ so there is the occasion to allocate the IRQ descriptor (that's
why probably a lot of drivers allocate the irq descriptor in there
using irq_create_mapping()).

>> IIUC for the hierarchical domains the mapping creation should be
>> propagated to all the domains in cascade and this is usually done
>> using the .alloc hook of the irq_domain_ops and at probe time we do
>> not still have the hwirq to pass to the parent GIC. Any idea on how to
>> approach this problem?
>
> I guess it needs to be done in some other hook on the
> irqchip in that case. Just not in .to_irq() on the gpiochip.

You mentioned .irq_request_resources(), but isn't it called too late
for IRQ allocation?

Thank you,

-- 
Carlo Caione