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PCI: Read capability list as dwords, not bytes

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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;
}