On Thu, 12 May 2016 16:19:26 +0100
Jon Hunter [off-list ref] wrote:

Some IRQ chips, such as GPIO controllers or secondary level interrupt
controllers, may require require additional runtime power management
control to ensure they are accessible. For such IRQ chips, it makes sense
to enable the IRQ chip when interrupts are requested and disabled them
again once all interrupts have been freed.

When mapping an IRQ, the IRQ type settings are read and then programmed.
The mapping of the IRQ happens before the IRQ is requested and so the
programming of the type settings occurs before the IRQ is requested. This
is a problem for IRQ chips that require additional power management
control because they may not be accessible yet. Therefore, when mapping
the IRQ, don't program the type settings, just save them and then program
these saved settings when the IRQ is requested (so long as if they are not
overridden via the call to request the IRQ).

Add a stub function for irq_domain_free_irqs() to avoid any compilation
errors when CONFIG_IRQ_DOMAIN_HIERARCHY is not selected.

Signed-off-by: Jon Hunter <redacted>

Reviewed-by: Marc Zyngier <redacted>

As discussed just before the 4.7 merge window, this patch is going to
uncover quite a few broken configurations (the main one being the PPI
triggers for the ARM architected timer, which seems to be wrong on a lot
of different platforms).

I'm proposing to put this patch[1] in the same queue in order to
uncover the guilty ones, but we have to be prepared for more breakage
(I've also identified kvmtool as a sinner).

Thanks,

	M.
[1] https://lkml.org/lkml/2016/5/9/546
-- 
Jazz is not dead. It just smells funny.