From f07852d6442c46c50b59c7e2acc8a1b291f9ab6d Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Sun, 13 Dec 2009 08:10:02 -0500 Subject: [PATCH] PCI: Rewrite pci_scan_slot The Alternate Routing-ID Interpretation capability allows a single device to have up to 256 functions. They can be populated sparsely, so the current technique of scanning every eighth function is not guaranteed to find them all. By introducing a 'next_fn' function pointer, we can use the linked list of functions in the ARI capability to scan all the functions which exist. We can then speed up the pci_scan_slot by skipping the scan of subsequent devfns for PCIe devices which are the direct children of Root Ports or Downstream Ports. These devices are only permitted to implement device 0, unless they are ARI devices, in which case they'll be scanned by the ARI code above. Signed-off-by: Matthew Wilcox Signed-off-by: Jesse Barnes --- drivers/pci/probe.c | 56 +++++++++++++++++++++++++++++++++++++-------- 1 file changed, 47 insertions(+), 9 deletions(-) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 446e4a94d7d3..dd64310a735e 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1081,6 +1081,37 @@ struct pci_dev *__ref pci_scan_single_device(struct pci_bus *bus, int devfn) } EXPORT_SYMBOL(pci_scan_single_device); +static unsigned next_ari_fn(struct pci_dev *dev, unsigned fn) +{ + u16 cap; + unsigned pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ARI); + if (!pos) + return 0; + pci_read_config_word(dev, pos + 4, &cap); + return cap >> 8; +} + +static unsigned next_trad_fn(struct pci_dev *dev, unsigned fn) +{ + return (fn + 1) % 8; +} + +static unsigned no_next_fn(struct pci_dev *dev, unsigned fn) +{ + return 0; +} + +static int only_one_child(struct pci_bus *bus) +{ + struct pci_dev *parent = bus->self; + if (!parent || !pci_is_pcie(parent)) + return 0; + if (parent->pcie_type == PCI_EXP_TYPE_ROOT_PORT || + parent->pcie_type == PCI_EXP_TYPE_DOWNSTREAM) + return 1; + return 0; +} + /** * pci_scan_slot - scan a PCI slot on a bus for devices. * @bus: PCI bus to scan @@ -1094,21 +1125,28 @@ EXPORT_SYMBOL(pci_scan_single_device); */ int pci_scan_slot(struct pci_bus *bus, int devfn) { - int fn, nr = 0; + unsigned fn, nr = 0; struct pci_dev *dev; + unsigned (*next_fn)(struct pci_dev *, unsigned) = no_next_fn; + + if (only_one_child(bus) && (devfn > 0)) + return 0; /* Already scanned the entire slot */ dev = pci_scan_single_device(bus, devfn); if (dev && !dev->is_added) /* new device? */ nr++; - if (dev && dev->multifunction) { - for (fn = 1; fn < 8; fn++) { - dev = pci_scan_single_device(bus, devfn + fn); - if (dev) { - if (!dev->is_added) - nr++; - dev->multifunction = 1; - } + if (pci_ari_enabled(bus)) + next_fn = next_ari_fn; + else if (dev && dev->multifunction) + next_fn = next_trad_fn; + + for (fn = next_fn(dev, 0); fn > 0; fn = next_fn(dev, fn)) { + dev = pci_scan_single_device(bus, devfn + fn); + if (dev) { + if (!dev->is_added) + nr++; + dev->multifunction = 1; } } -- 2.39.5