On Thursday 03 March 2016 13:01:13 Marc Zyngier wrote:

quoted

+/* Routines to acknowledge, disable and enable interrupts */
+static void rps_mask_irq(struct irq_data *d)
+{
+     u32 mask = BIT(d->hwirq);
+
+     iowrite32(mask, rps_data.base + RPS_MASK);

I do question the use of iowrite32 here (and its ioread32 pendent
anywhere else), as it actually translates in a writel, which contains a
memory barrier. Do you have any case that requires the use of such a
barrier? if not, consider switching to relaxed accessors (which are the

I really ask everyone to do the opposite: we have seen several drivers
blindlessly using the relaxed accessors and actually introducing bugs
that way, so I'd rather see the readl/writel ones used by default.

In any performance critical code, it's reasonable to take a closer
look and use the relaxed version with an added comment explaining
why it's safe there.

	Arnd