On Mon, 4 Feb 2008, Bjorn Helgaas wrote: > > I'm sure you're right, but I don't understand why yet. Here's what > I think is happening; please correct me where I'm going wrong: > > 1) enumerate PNP & ACPI devices > 2) initialize PNP & ACPI drivers > 2a) register ACPI PCI root bridge driver, which enumerates PCI > devices behind the bridge > 2b) register PNP system driver and reserve resources (this is > where the current quirk skips some reservations) > 3) initialize PCI drivers > 3a) register intel8x0 sound driver and reserve conflicting > resources So where in this would you put the pcibios_init() -> pcibios_resource_survey() call (it's a subsys_initcall)? THAT is the thing that actually registers the PCI resurces we've found into the resource tree! It's very inconveniently placed as-is, since it literally depends on the whole initcall ordering (and the link order within that subsys_initcall thing), and all of this is architecture-driven rather than driven from some central place. So this is the thing that I think should happen before any PnP or ACPI drivers actually start registerign themselves (but obviously needs to happen after the PCI buses have been enumerated). The ACPI/PnP tables shouldn't be able to break the enumeration of the actual hardware devices, now should it? > I think you're suggesting that we should do 2a first, to enumerate all > PCI devices, and only later do 2b. But I don't know how to accomplish > that cleanly. We should enumerate the PCI devices, then register their resources (and no, I'm not at *all* convinced it should happen as a separate subsys_initcall), and then register the PnP resources. So I think we should have roughly something like: - arch_initcall: this could enumerate the ACPI/PnP devices (but not register anything). Alternatively, do it as subsys_initcall, and just make sure it happens early with link-order. - subsys_initcall: this should do that pcibios_init() thing that surveys the resources (and the PCI enumeration needs to have happened before, probably in the same initcall thanks to link order) - PnP/ACPI resource allocation *after* it, but before driver loading (which wll cause new resources to be allocated). This could be fs_initcall, or whatever (that's what things like "acpi_event_init" already do). - regular drivers will come along much later, as part of driver_initcall, and by the time this happens, we've now reserved all resources we know about. Basically, we just want to register the most trust-worthy resources before we register anything less trust-worthy. And actual device probing simply tends to be more trust-worthy than any randomly broken ACPI/PnP tables. Linus _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
