From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Mon, 13 Jun 2011 23:14:47 +0100 Subject: [PATCH 2/3] ARM: gic: add OF based initialization In-Reply-To: <20110613165316.GF18161@ponder.secretlab.ca> References: <1307456541-11026-1-git-send-email-robherring2@gmail.com> <1307456541-11026-3-git-send-email-robherring2@gmail.com> <20110613165316.GF18161@ponder.secretlab.ca> Message-ID: <20110613221447.GI13643@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Jun 13, 2011 at 10:53:16AM -0600, Grant Likely wrote: > On Tue, Jun 07, 2011 at 09:22:20AM -0500, Rob Herring wrote: > > +- interrupt-controller : Identifies the node as an interrupt controller > > +- #interrupt-cells : Specifies the number of cells needed to encode an > > + interrupt source. The type shall be a and the value shall be 1. > > +- reg : Specifies base physical address(s) and size of the GIC registers. The > > + first 2 values are the GIC distributor register base and size. The 2nd 2 > > + values are the GIC cpu interface register base and size. > > +- irq-start : The first actual interrupt that is connected to h/w. > > Drop irq-start. That's a Linux internal implementation detail, and > Linux can easily handle dynamic assignment of irq ranges. Something has to be done with the IRQs on GIC, because Linux probably won't have a 1:1 mapping between the hardware IRQ numbers and the Linux IRQ numbers Have you seen the patches from Marc which deal with the per-CPU interrupts by creating individual Linux IRQ numbers for each CPU for each per-CPU interrupt? So you can end up with 16 per-CPU x 4 CPUs = 64 Linux interrupts for 16 "hardware" interrupts. How would DT deal with that - and how would you specify a connection between a per-CPU PMU and one of the per-CPU interrupts? The sensible thing from a DT point of view I think would be to ignore that abstraction, and have some kind of mapping layer between DT and drivers which knew about that. But that sounds like a world of pain.