ARM: orion: Fix for certain sequence of request_irq can cause irq storm
ARM: orion: Fix for certain sequence of request_irq can cause irq storm

The problem is that hardware handled by arm/plat-orion/gpio.c,
require ack for edge irq, and no ack for level irq.

The code handle this issue, by two "struct irq_chip_type" per
one "struct irq_chip_generic". For one "struct irq_chip_generic"
irq_ack pointer is setted, for another it is NULL.

But we have only one mask_cache per two "struct irq_chip_type".
So if we
1)unmask interrupt A for "edge type" trigger,
2)unmask interrupt B for "level type" trigger,
3)unmask interrupt C for "edge type",

we, because of usage of generic irq_gc_mask_clr_bit/irq_gc_mask_set_bit,
have hardware configured to trigger interrupt B on "edge type",
because of shared mask_cache. But kernel think that B is "level type",
so when interrupt B occur via "edge" reason, we don't ack it,
and B triggered again and again.

Signed-off-by: Evgeniy A. Dushistov <33ef474d644ae25e5bbba24fb01189cc6a985106@mail.ru>
Link: 47584e8978b3381e5532355cefb26b600ce429d1@fifteen
Signed-off-by: Jason Cooper <68c46a606457643eab92053c1c05574abb26f861@lakedaemon.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs