On Wed, 2019-06-12 at 15:16 +1000, Benjamin Herrenschmidt wrote: > pci_msi_create_irq_domain -> pci_msi_domain_update_chip_ops will > set those two already since the driver sets MSI_FLAG_USE_DEF_CHIP_OPS > > Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org> > --- > > [UNTESTED] > > Just something I noticed while browsing through those drivers in > search of ways to factor some of the code. > > That leads to a question here: > > Some MSI drivers such as this one (or any using the defaults > mask/unmask > provided by drivers/pci/msi.c) only call the PCI MSI mask/unmask > functions. > > Some other drivers call those PCI function but *also* call the parent > mask/unmask (giv-v2m for example) which generally is the inner domain > which just itself forwards to its own parent.
.../... So I looked at x86 and it also only uses pci_msi_unmask_irq, it doesn't mask at the parent level. And it also specifies those explicitly which isn't necessary so the same trivial cleanup patch could be done (happy to do it unless I missed something here). Question: If that's indeed the rule we want to establish, should we consider making all MSI controllers just use the PCI masking and remove the forwarding to the parent ? The ones that do the parent, at least in drivers/irqchip/* and drivers/pci/controller/* (ther are more in arch code) are all the GIC ones (v2m, v3-its, v3-mbi), alpine which was copied on GIC I think, tango and dwc. The other approach would be to make the generic ops setup by pci_msi_domain_update_chip_ops call the parent as well .. if there is one and it has corresponding mask/unmask callbacks. That means things like armada_370 would be unaffected since their "middle" irqdomain chip doesn't have them, at least until somebody decides that masking at the parent level as well is a good thing. I *think* it would also work for x86 since the parent in that case is x86_vector_domain which also doesn't have mask and unmask callbacks, so it would be a nop change. Let me know what you think. Cheers, Ben.