[+cc Rob, cover https://lore.kernel.org/r/20200826111628.794979401@xxxxxxxxxxxxx/ this https://lore.kernel.org/r/20200826112333.992429909@xxxxxxxxxxxxx/] On Wed, Aug 26, 2020 at 01:17:02PM +0200, Thomas Gleixner wrote: > From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > > The arch_.*_msi_irq[s] fallbacks are compiled in whether an architecture > requires them or not. Architectures which are fully utilizing hierarchical > irq domains should never call into that code. > > It's not only architectures which depend on that by implementing one or > more of the weak functions, there is also a bunch of drivers which relies > on the weak functions which invoke msi_controller::setup_irq[s] and > msi_controller::teardown_irq. > > Make the architectures and drivers which rely on them select them in Kconfig > and if not selected replace them by stub functions which emit a warning and > fail the PCI/MSI interrupt allocation. Sorry, I really don't understand this, so these are probably stupid questions. If CONFIG_PCI_MSI_ARCH_FALLBACKS is defined, we will supply implementations of: arch_setup_msi_irq arch_teardown_msi_irq arch_setup_msi_irqs arch_teardown_msi_irqs default_teardown_msi_irqs # non-weak You select CONFIG_PCI_MSI_ARCH_FALLBACKS for ia64, mips, powerpc, s390, sparc, and x86. I see that all of those arches implement at least one of the functions above. But x86 doesn't and I can't figure out why it needs to select CONFIG_PCI_MSI_ARCH_FALLBACKS. I assume there's a way to convert these arches to hierarchical irq domains so they wouldn't need this at all? Is there a sample conversion to look at? And I can't figure out what's special about tegra, rcar, and xilinx that makes them need it as well. Is there something I could grep for to identify them? Is there a way to convert them so they don't need it? > --- a/include/linux/msi.h > +++ b/include/linux/msi.h > @@ -193,17 +193,38 @@ void pci_msi_mask_irq(struct irq_data *d > void pci_msi_unmask_irq(struct irq_data *data); > > /* > - * The arch hooks to setup up msi irqs. Those functions are > - * implemented as weak symbols so that they /can/ be overriden by > - * architecture specific code if needed. > + * The arch hooks to setup up msi irqs. Default functions are implemented s/msi/MSI/ to match the one below. > + * as weak symbols so that they /can/ be overriden by architecture specific > + * code if needed. These hooks must be enabled by the architecture or by > + * drivers which depend on them via msi_controller based MSI handling.
