Handling multiple GPIO controllers in 8xxx GPIO driver

[Tabi Timur-B04825]

Grant Likely wrote:
> A chained handler has an expedited path through the interrupt code for
> handling it (basically, it skips handling it at the parent controller
> and passes through to the child, but it cannot handle multiple chained
> children on a single irq input.

So you can't do a shared chained handler?  If the chained handler returns 
IRQ_NONE, the interrupt code just gives up?

Why is it called a "chained" handler?  Where's the chain?

I'm trying to understand the core interrupt code, and I can't seem to find 
any descriptions of it.

-- 
Timur Tabi
Linux kernel developer at Freescale