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PCI: Read capability list as dwords, not bytes 

Reading both the capability ID and "next" pointer at the same time lets us
parse the list with half the number of config reads.

Signed-off-by: Sean O. Stalley <sean.stalley@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Sean O. Stalley 2015-04-02 14:10:19 -07:00 committed by Bjorn Helgaas
parent 387d37577f
commit 55db3208f2
1 changed files with 7 additions and 4 deletions
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11
drivers/pci/pci.c
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@ -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;
}