Messages in this thread Patch in this message | | | From | "Sean O. Stalley" <> | Subject | [PATCH] Read ID & Pointer from PCI Capabilities List in 1 call | Date | Thu, 2 Apr 2015 14:10:19 -0700 |
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Reading both fields at the same time lets us parse the list with half the number of configspace reads.
Signed-off-by: Sean O. Stalley <sean.stalley@intel.com> --- drivers/pci/pci.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 5e3c8e9..db7f3d6 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -145,19 +145,22 @@ static int __pci_find_next_cap_ttl(struct pci_bus *bus, unsigned int devfn, u8 pos, int cap, int *ttl) { u8 id; + u16 ent; + + pci_bus_read_config_byte(bus, devfn, pos, &pos); while ((*ttl)--) { - pci_bus_read_config_byte(bus, devfn, pos, &pos); if (pos < 0x40) break; pos &= ~3; - pci_bus_read_config_byte(bus, devfn, pos + PCI_CAP_LIST_ID, - &id); + pci_bus_read_config_word(bus, devfn, pos, &ent); + + id = ent & 0xff; if (id == 0xff) break; if (id == cap) return pos; - pos += PCI_CAP_LIST_NEXT; + pos = (ent >> 8); } return 0; } -- 1.9.1
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