On Tue, Dec 20, 2016 at 11:52:58AM +0000, Marc Zyngier wrote:
> On 20/12/16 11:06, Geetha sowjanya wrote:
> > From: Tirumalesh Chalamarla <tchalama...@caviumnetworks.com>
> > +#ifdef CONFIG_CAVIUM_ERRATUM_28168
> > +/*
> > + * Cavium ThunderX erratum 28168
> > + *
> > + * Due to erratum #28168 PCI-inbound MSI-X store to the interrupt
> > + * controller are delivered to the interrupt controller before older
> > + * PCI-inbound memory stores are committed. Doing a sync on SMMU
> > + * will make sure all prior data transfers are completed before
> > + * invoking ISR.
> > + *
> > + */
> > +void dev_smmu_tlb_sync(struct device *dev)
> > +{
> > + struct iommu_fwspec *fwspec = dev->iommu_fwspec;
> > + struct arm_smmu_device *smmu = fwspec_smmu(fwspec);
> > +
> > + if (smmu)
> > + __arm_smmu_tlb_sync(smmu);
> > +}
> > +#endif
>
> I'll let Robin and Will comment on this, but it strikes be as rather odd
> that nothing will happen if the SMMU is in bypass or simply compiled
> out. So this workaround is at best incomplete.
Agreed. Unless the SMMU is the cause of the issue, relying on it to
implement the workaround is fragile and unnecessarily introduces a linkage
between SMMU driver internals and the interrupt handling code.
Not a fan.
Will
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