On Wed, Jun 03, 2015 at 04:12:24PM +0100, Guenter Roeck wrote: [...] > >> After looking into this some more, I think the wrinkle may be that > >> pci_read_bridge_bases() and thus pci_read_bridge_io() isn't called > >> on probe-only systems (if PCI_PROBE_ONLY is set). A secondary > > > > That's what we would like to change :) > > > > https://lkml.org/lkml/2015/5/21/359 > > Yes, that should help. I had a brief look last night and concluded > that this would require changes all over the place, which your patch > pretty much confirms. Glad that you are tackling it - changes all over > the place spell trouble and would probably require more time than I have > available to spend on the problem. Eh, trouble did not even start because we have just tested it on ARM/ARM64 systems (that's all I can do no sign of testing on any other arch), so I do not expect it will be merged quickly, it will take me time to get all the required acks. I should be able to send a v2 beginning of next week. > >> problem is that pci_read_bridge_io() does not enable a resource > >> if it is explicitly disabled (base > limit), but the subsequent call > >> to pci_bridge_check_ranges() unconditionally enables it. > >> > >> Not really sure how to address this; my current code checks IO support > >> in both pci_read_bridge_io() and pci_bridge_check_ranges(). And since > >> pci_read_bridge_io() is not always called, I don't see how it might > >> be possible to get rid of pci_bridge_check_ranges(), or even the check > >> for IO support in pci_bridge_check_ranges(). > >> > >>> While at it, do you think it is reasonable to also claim the bridge > >>> windows (resources) in the respective pci_read_bridge_* calls ? > >>> > >>> Is there a reason why we don't/can't do it ? I noticed that on > >>> PROBE_ONLY systems on ARM/ARM64 at the moment we do not claim > >>> the bridge apertures and this is not correct, see below: > >>> > >>> [5.980127] pcieport 0000:00:02.1: can't enable device: BAR 8 > >>> [mem 0xbff00000 - 0xbfffffff] not claimed > >>> [5.988056] pcieport: probe of 0000:00:02.1 failed with error -22 > >>> > >> Is this when trying my patches or with the current upstream code ? > > > > It is upstream code with a couple of ARM64 related patches not yet > > merged. Still, it shows an issue that must be tackled. > > > > It is not caused by your patches but it can be solved by them. > > On PROBE_ONLY systems, all resources must be claimed (since they > > are not reassigned, hence not claimed by the code that reassigns them), > > otherwise we can't enable a device resources (ie pcibios_enable_device > > calls pci_enable_resources that fails, since resources are not claimed). > > > > That's why we are suggesting claiming the bridge apertures as soon > > as they are read from the base registers, even on PROBE_ONLY systems. > > > > I think that's the only approach Bjorn would accept, otherwise > > we will have to fiddle with PROBE_ONLY on ARM64, and either avoid calling > > pci_enable_resources or avoid checking if a resource is claimed in > > pci_enable_resources, neither solution seems sane to me. > > > > Looks like I'll need one of those arm64 systems at some point ;-). > > Where is your patch in respect to acceptance ? Would it make sense to > merge it into my code and base my patch(es) on it, or do you expect > major changes which would make that difficult ? I have a tweak to v1, I will post v2 next week and copy you in. Acceptance, I think it received review only from ARM guys/platforms so we are still far from merging it. Thanks, Lorenzo -- 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
