On Mon, Nov 29, 2021 at 02:54:18PM +0000, Robin Murphy wrote:

On 2021-11-29 14:42, Thomas Gleixner wrote:

quoted

On Mon, Nov 29 2021 at 13:13, Robin Murphy wrote:

quoted

On 2021-11-29 10:55, Will Deacon wrote:

quoted

quoted

-	}
+	smmu->evtq.q.irq = msi_get_virq(dev, EVTQ_MSI_INDEX);
+	smmu->gerr_irq = msi_get_virq(dev, GERROR_MSI_INDEX);
+	smmu->priq.q.irq = msi_get_virq(dev, PRIQ_MSI_INDEX);

Prviously, if retrieval of the MSI failed then we'd fall back to wired
interrupts. Now, I think we'll clobber the interrupt with 0 instead. Can
we make the assignments to smmu->*irq here conditional on the MSI being
valid, please?

I was just looking at that too, but reached the conclusion that it's
probably OK, since consumption of this value later is gated on
ARM_SMMU_FEAT_PRI, so the fact that it changes from 0 to an error value
in the absence of PRI should make no practical difference.

It's actually 0 when the vector cannot be found.

Oh, -1 for my reading comprehension but +1 for my confidence in the patch
then :)

I'll let Will have the final say over how cautious we really want to be
here, but as far as I'm concerned it's a welcome cleanup as-is. Ditto for
patch #32 based on the same reasoning, although I don't have a suitable test
platform on-hand to sanity-check that one.

If, as it appears, msi_get_virq() isn't going to fail meaningfully after
we've successfully called platform_msi_domain_alloc_irqs() then it sounds
like the patch is fine. Just wanted to check though, as Spring cleaning at
the end of November raised an eyebrow over here :)

Will

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