On Fri, Jan 11, 2013 at 03:36:14PM +0000, Arnd Bergmann wrote: > On Friday 11 January 2013, Thierry Reding wrote: > > Right, it'll need #ifdefs around the arch_{setup,teardown}_msi_irq(). Or > > select PCI_MSI unconditionally. Once this is merged I was going to post > > a patch that enables PCI_MSI in tegra_defconfig anyway. But it might be > > better to keep it optional anyway since the remainder of the code copes > > with it properly. > > > Actually, we need something better than that. You cannot define > arch_setup_msi_irq in a tegra specific pci host driver, because that > will seriously mess up other platforms in multiplatform configurations > by giving a link error when they also define this function, or with a > run-time error when they don't support it. > > I think what we should do here is fix it the right way by adding > a pci host specific callback rather than an architecture specific > callback in drivers/pci/msi.c. There is already a default version > of arch_setup_msi_irqs (with s), and we can probably do the > same for arch_setup_msi_irq (without s) to fall back to the > arch version for most architectures. > Most architectures (at least powerpc, sparc, ia64 and x86) already > multiplex the msi handlers internally, but ARM does not because > there is only one implementation (iop33x) at the moment. > > We can add a generix multiplex and then move architectures over to > use it. I already hinted at that in one of the other subthreads. Having such a multiplex would also allow the driver to be built as a module. I had already thought about this when I was working on an earlier version of these patches. Basically these would be two ops attached to the host bridge, and the generic arch_setup_msi_irq() could then look that up given the struct pci_dev that is passed to it and call this new per- host bridge .setup_msi_irq(). Thierry
Attachment:
pgpWz69gdA22J.pgp
Description: PGP signature