On Wed, Aug 5, 2015 at 7:22 PM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > On 08/05/2015 06:38 PM, Yinghai Lu wrote: >> >> On Wed, Aug 5, 2015 at 6:14 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: >>> >>> >>> It only can avoid warning with bridge, and still have warning on >>> devices under the bridge. >>> >>> also would have problem on transparent bridges, like >>> >>> BRIDGE_A ---- BRIDGE_AA----DEVICE_AA >>> | >>> \-- BRIDGE_AB ---DEVICE_AB >>> >>> if only BRIDGE_A and BRIDGE_AA are transparent, and BRIDGE_AB is not. >>> >>> and if pci_bridge_supports_io() return false for BRIDGE_A. >>> >>> We will have all three bridges have PCI_BUS_FLAGS_SUPPORTS_IO cleared. >>> so all will not been sized and will not get assigned io port resource. >>> >>> later DEVICE_AA could root bus io port as parent, and get io resource >>> assigned. >>> but DEVICE_AB will not get assigned. >>> >>> so we should get rid of pci_bridge_supports_io(), and just check root >>> resource IO port. >> >> >> I would suggest this version instead: >> >> Subject: [PATCH] PCI: Only try to assign io port only if root bus support >> that >> > > Bjorn had asked me to move the IO support check out of > pci_bridge_check_ranges(). > It looks like you want to keep it there. > > Can you explain your reasons ? Sorry, I just don't understand. in pci_alloc_child_bus(), child bus's bus_flags will be assigned with parent's bus_flags. so if one parent bus has bridge's io bar can not changed, then all children bus will also have same bus_flags, and their bridge io bar will not used. then if BRIDGE_AB is not transparent, we do need to use it's bridge io bar. -- 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
