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SubjectRe: [PATCH] Read ID & Pointer from PCI Capabilities List in 1 call
On Thu, Apr 02, 2015 at 02:10:19PM -0700, Sean O. Stalley wrote:
> 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>

Applied to pci/misc for v4.1, thanks Sean!

> ---
> 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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