On Mon, Aug 31, 2015 at 11:49:20AM -0500, Bjorn Helgaas wrote: > On Mon, Aug 31, 2015 at 11:33 AM, Lorenzo Pieralisi > <lorenzo.pieralisi@xxxxxxx> wrote: > > On Mon, Aug 31, 2015 at 02:28:03PM +0100, Bjorn Helgaas wrote: > >> On Sat, Aug 29, 2015 at 01:44:57PM +0100, Lorenzo Pieralisi wrote: > >> > On Fri, Aug 28, 2015 at 10:14:44PM +0100, Bjorn Helgaas wrote: > >> > > On Thu, Jul 30, 2015 at 02:13:59PM +0100, Lorenzo Pieralisi wrote: > >> > > > On ARM64 PROBE_ONLY PCI systems resources are not currently claimed, > >> > > > therefore they can't be enabled since they do not have a valid > >> > > > parent pointer; this in turn prevents enabling PCI devices on > >> > > > ARM64 PROBE_ONLY systems, causing PCI devices initialization to > >> > > > fail. > >> > > > >> > > Where does arm64 claim PCI BAR resources for the non-PROBE_ONLY case? > >> > > >> > arm64 (and arm) does not claim resources in arch code, they are always > >> > assigned in the respective host controllers (or the pcibios on arm), > >> > except for the PCI generic host when in PROBE_ONLY mode, where resources > >> > are neither claimed nor assigned (the reason for this patch to exist). > >> > ... > >> > > >> > > I know it must be there somewhere, but I don't see it. > >> > > >> > It is not there, it is done in the host controllers by assigning the > >> > resources (which also "claim" them by assigning the parent pointer). > >> > >> The host controller drivers should claim the apertures forwarded to > >> the PCI bus. For pci-host-generic, this happens when > >> gen_pci_parse_request_of_pci_ranges() calls devm_request_resource(). > > > > Yes, the generic host claims the apertures at DT probing time. > > > >> But that doesn't do anything for the BARs of the PCI devices > >> themselves, of course. > >> > >> If this patch fixes a problem that will occur in the future, when we > >> add arm/arm64 code to claim BARs, let's make this patch part of that > >> series. If it fixes a problem in the current tree, I'll merge it now, > >> but so far I haven't been able to make the connection between this > >> patch and a problem in the current code. > > > > It fixes a problem in the current tree (I mean when the PCI pull is > > merged - it contains code that enables PCI host generic on arm64), > > since without it PROBE_ONLY systems (ie PCI host generic on kvmtool) would > > try to enable resources and fail, since the resources were not claimed. > > > > It works the same way as arm, I will rework both arches when I am done > > refactoring the resource claiming implementation. > > > > Will picked it up already I do not know what's the best way to > > merge it I guess it can go via the arm64 tree if you do not have any > > objections. > > OK, if it fixes a problem in my v4.3 pull request, we need to merge > it. I missed the connection, probably because I was browsing the > v4.2-rc1 tree, which wouldn't have those changes. > > It's OK with me to merge it via the arm64 tree. Do you need me to do anything with this? It'd be nice to get it in before -rc1. The PCI changes have already been merged, and it'd be nice to mention the commit that this fixes. 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
