[PATCH 3/3] drm/pci: Use PCI Express Capability accessors

[Bjorn Helgaas]

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 at google.com>
---
 drivers/gpu/drm/drm_pci.c |   21 +++++----------------
 1 files changed, 5 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/drm_pci.c b/drivers/gpu/drm/drm_pci.c
index 50e26f2..86102a0 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)