On 12/10/2017 17:04, Linus Walleij wrote:
On Fri, Oct 6, 2017 at 7:08 AM, Phil Reid <preid@xxxxxxxxxxxxxxxxx> wrote:
The polarity of the irq could be altered
by additional logic (eg inverters) between the device and irq input device.
Marc Zyngier has pointed out that inverters should be modeled
using hierarchichal irq domains. You would need to add a new
irqchip to invert the line.
See this PDF:
https://elinux.org/images/8/8c/Zyngier.pdf
drivers/irqchips/irq-uniphier-aidet.c supports inversion of IRQs
for example. For this it uses irq_domain_create_hierarchy()
I guess it would be helpful with a reusable generic "inverter
irq chip", that you can just enable and slam into your device
tree to tell the system that a line is statically inverted, i.e.
non-programmable logic on the board.
G'day Linus.
Thanks for the pointers, I'll see what I can come up with.
--
Regards
Phil Reid
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