[Linux-Xtensa] Re: [patch 09/12] xtensa: allow platform and variant to initialize own irq chips

Chris Zankel chris at zankel.net
Thu Apr 23 13:03:19 PDT 2009


Hi Daniel,

Daniel Glöckner wrote:
> On 04/23/2009 07:20 PM, Chris Zankel wrote:
>>> Another possibility would be to select VARIANT_IRQ_SWITCH (or a
>>> dedicated new
>>> Kconfig option) in all SoCs that need additional IRQs.
>> Wasn't the original code before your patch just doing that?
> 
> Yes, but I wanted to decouple variant IRQs from the functionality provided
> by CONFIG_VARIANT_IRQ_SWITCH.

Could you elaborate a bit more on this? What's the (intended) difference 
between VARIANT_IRQ_SWITCH and VARIANT_IRQ?

Xtensa processors come with a number of interrupts, defined as 
XTENSA_NR_IRQS. Additional interrupts must be funneled through these 
interrupts through an external (eg. SoC) interrupt controller/switch.

I need to look a bit closers, but can't the variant code simply define 
its own irq_chip? We might need some tweaking in xtensa-irq.c for the 
cascaded interrupts, or the variant-irq.c has to register a handler with it.

Thanks,
-Chris


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