On Thu, Sep 29, 2011 at 10:30:09AM +0100, Jamie Iles wrote:

+#ifdef CONFIG_MULTI_IRQ_HANDLER
+static void vic_single_handle_irq(struct vic_device *vic, struct pt_regs *regs)
+{
+	u32 stat, irq;
+
+	stat = readl_relaxed(vic->base + VIC_IRQ_STATUS);
+	while (stat) {
+		irq = ffs(stat) - 1;
+		handle_IRQ(irq_domain_to_irq(&vic->domain, irq), regs);
+		stat &= ~(1 << irq);
+	}
+}
+
+asmlinkage void __exception_irq_entry vic_handle_irq(struct pt_regs *regs)
+{
+	int i;
+
+	for (i = 0; i < vic_id; ++i)
+		vic_single_handle_irq(&vic_devices[i], regs);
+}

And if we receive another interrupt after the read of the register, we'll
have to exit all the way back (possibly to userspace) before re-entering
the IRQ handling paths back to this point to process it.

Is there any particular reason folk are destroying the built-in efficiency
of the IRQ handling which is common-place in the existing assembly
approach?