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authorMatthew Wilcox <matthew@wil.cx>2009-12-13 08:10:02 -0500
committerJesse Barnes <jbarnes@virtuousgeek.org>2010-02-22 16:15:16 -0800
commitf07852d6442c46c50b59c7e2acc8a1b291f9ab6d (patch)
treed855a7bc7df8f3e84f1d267e060537ec011477c6 /drivers/pci
parentbee415ce427d1eab6cfb30221461c7d20cbf1903 (diff)
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 <willy@linux.intel.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'drivers/pci')
-rw-r--r--drivers/pci/probe.c56
1 files changed, 47 insertions, 9 deletions
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 446e4a94d7d..dd64310a735 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;
}
}