Messages in this thread | | | Subject | Re: Affinity for GIC irq line | From | valmiki <> | Date | Thu, 26 Apr 2018 09:19:40 +0530 |
| |
> On 25/04/18 04:23, valmiki wrote: >> Hi all, >> >> When an IRQ line is set affinity using irq_set_affinity, which calls >> irq_do_set_affinity, this API copies affinity mask to affinity variable >> in irq_common_data of this irq descriptor. > > It does a wee bit more. Crucially, it contains the line: > > ret = chip->irq_set_affinity(data, mask, force); Yes, i overlooked this part. > >> But as per ARM GICv2 document in order to drive a interrupt to a >> specific CPU we need to program GICD_ITARGETSRn register. >> >> But irq_set_affinity isn't writing to this register.Please correct me if >> I'm wrong i did not find code for this register being updated in >> irq_set_affinity flow. >> So how affinity is being set for an IRQ line ? > > I would have though that a function name such as "gic_set_affinity" was > clear enough? > >> If affinity was set successfully on what CPU does asm_do_IRQ run ? > > It runs on the CPU that the interrupt targets, I'd say. Thanks Marc. How does affinity for virtual irq work ? For example pci-xgene-msi.c has xgene_msi_set_affinity function which sets affinity for each virq. As per arm64/boot/dts/apm/apm-storm.dtsi they use GICv2. They are trying to map each virq to specific cpu but already GIC lines affinity is set, when this affinity would be used ?
What does /* Update MSI number to target the new CPU */ irqdata->hwirq = hwirq_to_canonical_hwirq(irqdata->hwirq) + target_cpu;
the above code do ? Already mapping for hwirq to virq is done by this time for this domain. Now if hwirq is updated its mapping doesn't it lead to wrong virq ?
Regards, Valmiki
--- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
| |