On Mon, Apr 18, 2016 at 11:01:54AM +0100, Lorenzo Pieralisi wrote: > On Fri, Apr 15, 2016 at 08:08:03AM -0500, Bjorn Helgaas wrote: > > On Tue, Apr 12, 2016 at 04:48:10PM +0100, Lorenzo Pieralisi wrote: > > [...] > > > > > The next patch removes the arm and arm64 pcibios_enable_device() > > > > implementations, which implies that arm and arm64 only need the generic > > > > version, which simply calls pci_enable_resources(). That assumes r->parent > > > > is set. > > > > > > > > After this patch, we'll call pci_bus_claim_resources() for the > > > > PCI_PROBE_ONLY case, and that sets r->parent for all the resources. > > > > > > > > Where does r->parent get set in the non-PCI_PROBE_ONLY case? Obviously > > > > that path *works*, because you're not changing anything there. I'd just > > > > like to have a hint that makes this change more obvious. > > > > > > On all ARM/ARM64 PCI controllers drivers I am aware of (apart from the > > > kvmtool PCI host controller which does require PCI_PROBE_ONLY, so we need > > > this patch), resources are always reassigned and the core code reassigning > > > them takes care of assigning their parent pointers too, to answer your > > > question. > > > > Here's what I find confusing. Consider these three cases: > > > > 1) Firmware programs no BARs and we reassign everything. We call > > pci_bus_assign_resources(), and the pci_assign_resource() ... > > allocate_resource() path makes sure everything is claimed. This is > > apparently the normal arm/arm64 path, and it already works. > > > > 2) Firmware programs all BARs and we set PCI_PROBE_ONLY. After this > > series, we'll claim the resources and remove the PCI_PROBE_ONLY > > special case in pcibios_enable_device(). This is great! > > > > 3) Firmware programs all BARs but we don't set PCI_PROBE_ONLY. We > > call pci_bus_assign_resources(), but I think it does nothing because > > everything is already assigned. The resources are not claimed and > > pci_enable_resources() will fail. > > I do not expect (1) and (3) to be different from a kernel resource > allocation perspective. > > If the core resource layer is asked to assign resources it will, > regardless of what FW programmed in the BARs (the BAR regions size > matters, that's it), I went through pci_bus_assign_resources() a couple > of times and I have to add a bit of debugging so give me the benefit of > the doubt please, but there is nothing that let me think it won't assign > resources (and therefore assign a parent pointer) if the resources are > already programmed correctly (actually I even think the kernel may > change what FW programmed according to its resource alloc policy). OK. If you're saying that even if FW programmed the BARs, the core will assign resources and set r->parent, that's all I'm looking for. I *would* like a comment where we test PCI_PROBE_ONLY to the effect that for PCI_PROBE_ONLY we call pci_bus_claim_resources(), and for !PCI_PROBE_ONLY, we claim the resources in pci_bus_assign_resources(). Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
