Messages in this thread | | | Date | Sat, 15 Aug 2009 11:55:03 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC patch 2/3] genirq: Add buslock support for irq chips on slow busses |
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* Mark Brown <broonie@opensource.wolfsonmicro.com> wrote:
> On Fri, Aug 14, 2009 at 12:20:49PM +0200, Thomas Gleixner wrote: > > On Fri, 14 Aug 2009, Pavel Machek wrote: > > > > AFAICT this means that driver would need to know what kind of IRQ it > > > is hooked to, right? That will lead to some ugly code in drivers that > > > can handle both normal and slowbus irqs, right? > > > Are there such drivers in reality ? > > Yes. The GPIO based stuff is the prime example but there's other > examples - one is the WM831x touchscreen (no driver in mainline > yet) which can use interrupts via the main interrupt controller on > the CPU but also has the option of bringing the interrupt signals > out to dedicated pins on the chip for direct connection to the CPU > precisely to avoid the overheads of these slow interrupt > controllers.
This would call for Thomas's first version of the patch, that is transparent to drivers - the IRQ subsystem will know how to lock access to the line.
How about implementing that first patch in a cleaner way - can we somehow express the slow-bus property purely via the irqchip? Or is that too lowlevel?
Ingo
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