Messages in this thread | | | Date | Wed, 6 Jul 2016 11:30:48 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [RFC PATCH v1] irqchip: add support for SMP irq router |
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On Wed, 6 Jul 2016, Marc Zyngier wrote: > On 05/07/16 20:24, Thomas Gleixner wrote: > > On Tue, 5 Jul 2016, Marc Zyngier wrote: > >> Hardcoded? No way. You simply implement a route allocator in your > >> driver, assigning them as needed. And yes, if you have more than 24 > >> interrupts, they get muxed. > > > > There is one caveat though. Under some circumstances (think RT) you want to > > configure which interrupts get muxed and which not. We really should have that > > option, but yes for anything which has less than 24 autorouting is the way to > > go. > > Good point. I can see two possibilities for that: > > - either we describe this DT with some form of hint, indicating what are > the inputs that can be muxed to a single output. Easy, but the DT guys > are going to throw rocks at me for being Linux-specific.
That's not necessarily Linux specific. The problem arises with any other OS as well.
> - or we have a way to express QoS in the irq subsystem, and a driver can > request an interrupt with a "make it fast" flag. Of course, everybody > and his dog are going to ask for it, and we're back to square one.
That and the driver does not know about the particular application scenario/system configuration.
> Do we have a way to detect which interrupt is more likely to be > sensitive to muxing? My hunch is that if it is requested with > IRQF_SHARED, then it is effectively muxable. Thoughts?
That's too late. request_irq happens _after_ the interrupt is set up and the routing established.
Thanks,
tglx
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