On Thu, Jan 09, 2014 at 07:17:29PM +0000, Stephen Boyd wrote:

On 01/09/14 02:49, Will Deacon wrote:

quoted

quoted

+static irq_handler_t cpu_handler;
+
+static irqreturn_t cpu_pmu_dispatch_irq(int irq, void *dev)
+{
+	struct arm_pmu *arm_pmu = *(struct arm_pmu **)dev;
+	return cpu_handler(irq, arm_pmu);
+}

I don't like this bit -- having a global cpu_handler field is going to
interfere with the big.LITTLE work and casting the per-cpu dev token is also
pretty hacky.

However, you're forced down this route by the need to invoke the armpmu IRQ
dispatcher. Now, that only exists as a workaround for the braindead
interrupt routing on the u8500 (they OR'd all the PMU SPIs together) -- it's
not a problem that will affect a system using PPIs. If you look, there is
only one use of the thing in: arch/arm/mach-ux500/cpu-db8500.c.

So, we could rename that callback to make it clear that it's not so much an
IRQ handler wrapper as a specific hack to deal with broken SPIs. Then the
cpu_pmu code can neglect to make the callback if it's using PPI.

What do you think?

Yeah I hate this bouncing layer too but it was the best I could come up
with. I'll rename it to 'armpmu_dispatch_spi_irq' (bikeshedding welcome).

That sounds fine.

We can avoid the hacky cast of the per-cpu dev token by using the
cpu_pmu pointer directly, but we'll still need to pass something to the
percpu interrupt handler otherwise the genirq layer doesn't allow us to
request the PPI. I can pass hw_events I guess. Is that what you're
thinking? Or were you thinking that we could just use
cpu_pmu->handle_irq as the handler argument in request_percpu_irq()? I
can't figure out how that is supposed to work.

Actually, I was thinking you could remove cpu_pmu_dispatch_irq completely
and just pass the actual handler straight through to request_percpu_irq. On
arm64 we pass the hw_events as the pcpu token, so I'd be inclined to do the
same here unless there's a good reason not to.

Cheers,

Will