On Wed, Jun 24, 2015 at 12:14:43AM +0100, Benjamin Herrenschmidt wrote: > On Tue, 2015-06-23 at 18:02 -0500, Bjorn Helgaas wrote: > > On Tue, Jun 23, 2015 at 5:46 PM, Benjamin Herrenschmidt > > <benh@xxxxxxxxxxxxxxxxxxx> wrote: > > > On Tue, 2015-06-02 at 15:55 +0100, Lorenzo Pieralisi wrote: > > >> While at it, do you think it is reasonable to also claim the bridge > > >> windows (resources) in the respective pci_read_bridge_* calls ? > > > > > > No, don't claim in read. There's a clear distinction between gathering > > > resources and claiming them, and we need to keep that. > > > > > > Some fixups might happen in between the two for example. > > > > Are there any existing fixups like that? Concrete examples would help > > figure out the best way forward. > > Not off the top of my mind, it's been a long time since I wrote the > resource claiming stuff in arch/powerpc but it does make me nervous. We > collect resources when probing and we claim in the survey, those have > been historically very distinct steps. Yes, that makes me nervous too, that's why I posted my patch as an RFC/RFT, I think there is little debate in moving pci_read_bridge_bases() to core PCI, claiming the resources is a different question though, and I can't have the overall picture since it _seems_ arch specific (I know Bjorn does not agree with this though - it might be due to platform specific quirks) even if it should not. > > Most arches call pci_read_bridge_bases() from pcibios_fixup_bus(). I > > think that's a poor place to do it because it's code that normally > > doesn't have to be arch-specific. Resource claiming is also usually > > done from arch code, and it shouldn't be arch-specific either. > > Claiming as in putting in the resource tree etc... is different from > actually reading the values from the HW and is traditionally done much > later, no ? > > > If we move both the read and claim into generic code, then we might > > need to make sure there's a fixup phase in between or something. > > Well, then there's a more general argument to be made as to whether we > want the claiming to be "merged" as part of the probing/reading I > suppose... On PROBE_ONLY systems (that are the systems I really wanted to cover by claiming as soon as pci_read_bridge_bases() is executed) I think we all agree that merging the claiming/reading is sane (but I also think that Bjorn is not happy with that :), I mean it should not be PROBE_ONLY dependent). > Then there's also the case where everything gets fully reassigned, like > powernv, where the "read" phase is really only about sizing device > BARs... Exactly, there claiming right after reading should not be a problem either. How do you want me to proceed ? Should I make bridge resources claiming in PCI core PROBE_ONLY ? Or move it to ARM specific hooks ? I will certainly move pci_read_bridge_bases() to core code since this changes nothing to current behaviour and must be consolidated regardless. Thoughts appreciated. 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
