drm/pci: Use PCI Express Capability accessors

Use PCI Express Capability access functions to simplify this code a bit.
For non-PCIe devices or pre-PCIe 3.0 devices that don't implement the Link
Capabilities 2 register, pcie_capability_read_dword() reads a zero.

Since we're only testing whether the bits we care about are set, there's no
need to mask out the other bits we *don't* care about.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 5 insertions, 16 deletions

diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c
index 50e26f2d198e..86102a08f65c 100644
--- a/drivers/gpu/drm/drm_pci.c
+++ b/drivers/gpu/drm/drm_pci.c
@@ -469,41 +469,30 @@ EXPORT_SYMBOL(drm_pci_exit);
 int drm_pcie_get_speed_cap_mask(struct drm_device *dev, u32 *mask)
 {
         struct pci_dev *root;
-        int pos;
-        u32 lnkcap = 0, lnkcap2 = 0;
+        u32 lnkcap, lnkcap2;
 
         *mask = 0;
         if (!dev->pdev)
                 return -EINVAL;
 
-        if (!pci_is_pcie(dev->pdev))
-                return -EINVAL;
-
         root = dev->pdev->bus->self;
 
-        pos = pci_pcie_cap(root);
-        if (!pos)
-                return -EINVAL;
-
         /* we've been informed via and serverworks don't make the cut */
         if (root->vendor == PCI_VENDOR_ID_VIA ||
             root->vendor == PCI_VENDOR_ID_SERVERWORKS)
                 return -EINVAL;
 
-        pci_read_config_dword(root, pos + PCI_EXP_LNKCAP, &lnkcap);
-        pci_read_config_dword(root, pos + PCI_EXP_LNKCAP2, &lnkcap2);
-
-        lnkcap &= PCI_EXP_LNKCAP_SLS;
-        lnkcap2 &= 0xfe;
+        pcie_capability_read_dword(root, PCI_EXP_LNKCAP, &lnkcap);
+        pcie_capability_read_dword(root, PCI_EXP_LNKCAP2, &lnkcap2);
 
-        if (lnkcap2) { /* PCIE GEN 3.0 */
+        if (lnkcap2) {  /* PCIe r3.0-compliant */
                 if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_2_5GB)
                         *mask |= DRM_PCIE_SPEED_25;
                 if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_5_0GB)
                         *mask |= DRM_PCIE_SPEED_50;
                 if (lnkcap2 & PCI_EXP_LNKCAP2_SLS_8_0GB)
                         *mask |= DRM_PCIE_SPEED_80;
-        } else {
+        } else {        /* pre-r3.0 */
                 if (lnkcap & PCI_EXP_LNKCAP_SLS_2_5GB)
                         *mask |= DRM_PCIE_SPEED_25;
                 if (lnkcap & PCI_EXP_LNKCAP_SLS_5_0GB)