[+cc Yinghai] On Wed, Aug 28, 2013 at 7:33 AM, Johannes Thumshirn <johannes.thumshirn@xxxxxx> wrote: > Hi List, > > I have a rather odd problem with a PCIe swicht/bridge which does not get > enumerated correctly. If I issue _two_ manual rescans of the PCI bus via sysfs, > everything get setup correctly. To work around the problem I decided to make a > platform specific PCI quirk (for the embedded system I'm on, to not break > anything else) and issue the pci_rescan_bus() myself as a "final" fixup. However > this does not have any effect at all. > > Does anyone have an idea what I could do wrong? A rescan doesn't really do anything differently from the initial boot-time scan. Maybe there's an issue with the switch taking a long time to respond after reset? But that doesn't seem likely, because if you do manual rescans via sysfs, that should give plenty of time and you wouldn't have to do it *twice*. Maybe there's some resource or bus number allocation issue such that we don't even get down to the problem switch the first couple of times? > Example: > root@generic-powerpc:~# lspci -tv > -[0000:00]---00.0-[01]-- > root@generic-powerpc:~# echo 1 > /sys/bus/pci/rescan > [...] > root@generic-powerpc:~# lspci -tv > -[0000:00]---00.0-[01-05]----00.0-[02-05]--+-01.0-[03]-- > +-02.0-[04]-- > \-03.0-[05]-- > root@generic-powerpc:~# echo 1 > /sys/bus/pci/rescan > [...] > root@generic-powerpc:~# lspci -tv > -[0000:00]---00.0-[01-05]----00.0-[02-05]--+-01.0-[03]----00.0 Silicon Image, Inc. SiI 3132 Serial ATA Raid II Controller > +-02.0-[04]-- > \-03.0-[05]--+-00.0 Pericom Semiconductor Device 400e > +-00.1 Pericom Semiconductor Device 400e > \-00.2 Pericom Semiconductor Device 400f I bet that's what's happening: the first lspci shows the 00:00.0 bridge leading only to bus 01. The second lspci shows 00:00.0 leading to [bus 01-05], so its bus number aperture has been reconfigured. On x86 the BIOS typically configures all the bridges so we can see all the devices. But it looks like your platform doesn't, and the Linux paths that do similar configuration are not as well exercised. Can you collect a complete dmesg log including initial boot and your manual sysfs rescansand attach it to a new bugzilla report at https://bugzilla.kernel.org/enter_bug.cgi?component=PCI&product=Drivers ? There might be some generic way we can fix this. Bjorn > "My" rescan quirk: > #if CONFIG_PCI > static DEFINE_MUTEX(rescan_mutex); > static void xm51_fixup_bridge(struct pci_dev *dev) > { > struct pci_bus *b = NULL; > > mutex_lock(&rescan_mutex); > while((b = pci_find_next_bus(b)) != NULL) > pci_rescan_bus(b); > mutex_unlock(&rescan_mutex); > } > DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_FREESCALE, 0x0401, xm51_fixup_bridge); > #endif > > > Thanks in advance, > Johannes > -- > 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 -- 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
