PCI: Add pci_bus_crs_vendor_id() to detect CRS response data

Add pci_bus_crs_vendor_id() to determine whether data returned for a config
read of the Vendor ID indicates a Configuration Request Retry Status (CRS)
response.

Per PCIe r3.1, sec 2.3.2, this data is only returned if:

  - CRS Software Visibility is enabled,
  - a config read includes both bytes of the Vendor ID, and
  - the read receives a CRS completion

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
[bhelgaas: changelog, change name to pci_bus_crs_vendor_id(), make static
in probe.c, use it in pci_bus_read_dev_vendor_id()]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 150093817c5973109221b81d0c22d13b91f2fe63..5e001bbc2392a6460d647d2808701e104530dbac 100644 (file)
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1853,6 +1853,11 @@ struct pci_dev *pci_alloc_dev(struct pci_bus *bus)
 }
 EXPORT_SYMBOL(pci_alloc_dev);
 
+static bool pci_bus_crs_vendor_id(u32 l)
+{
+       return (l & 0xffff) == 0x0001;
+}
+
 bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
                                int crs_timeout)
 {
@@ -1872,7 +1877,7 @@ bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *l,
         * by the PCIe spec.  Ignore the device ID and only check for
         * (vendor id == 1).
         */
-       while ((*l & 0xffff) == 0x0001) {
+       while (pci_bus_crs_vendor_id(*l)) {
                if (!crs_timeout)
                        return false;