Hi,

Some more info on chained irq vs mux below that might
help.

* Tony Lindgren [off-list ref] [190219 15:36]:

* Lokesh Vutla [off-list ref] [190219 08:51]:

quoted

With this can you tell me how can we not have a device-tree and still support
irq allocation?

Using standard dts reg property to differentiate the interrupt
router instances. And if the interrupt router is a mux, you should
treat it as a mux rather than a chained interrupt controller.

We do have drivers/mux nowadays, not sure if it helps in this case
as at least timer interrupts need to be configured very early.

Adding Linus Walleij to Cc since he posted a good test to
consider if something should use chained (or nested) irq:

"individual masking and ACKing bits and can all be used at the
 same time" [0]

Not sure if we have that documented somewhere?

But seems like the interrupt router should be set up as
a separate mux driver talking with firmware that the
interrupt controller driver calls on request_irq()?

Cheers,

Tony


[0] https://marc.info/?l=linux-omap&m=155065629529311&w=2


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