drm/radeon/kms: auto detect pcie link speed from root port

This check the root ports supported link speeds and enables
GEN2 mode if the 5.0 GT link speed is available.

The first 3.0 cards are SI so they will probably need more investigation.

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/rv770.c b/drivers/gpu/drm/radeon/rv770.c
index eb4704e72bdb..ca8ffec10ff6 100644
--- a/drivers/gpu/drm/radeon/rv770.c
+++ b/drivers/gpu/drm/radeon/rv770.c
@@ -1112,6 +1112,8 @@ static void rv770_pcie_gen2_enable(struct radeon_device *rdev)
 {
         u32 link_width_cntl, lanes, speed_cntl, tmp;
         u16 link_cntl2;
+        u32 mask;
+        int ret;
 
         if (radeon_pcie_gen2 == 0)
                 return;
@@ -1126,6 +1128,15 @@ static void rv770_pcie_gen2_enable(struct radeon_device *rdev)
         if (ASIC_IS_X2(rdev))
                 return;
 
+        ret = drm_pcie_get_speed_cap_mask(rdev->ddev, &mask);
+        if (ret != 0)
+                return;
+
+        if (!(mask & DRM_PCIE_SPEED_50))
+                return;
+
+        DRM_INFO("enabling PCIE gen 2 link speeds, disable with radeon.pcie_gen2=0\n");
+
         /* advertise upconfig capability */
         link_width_cntl = RREG32_PCIE_P(PCIE_LC_LINK_WIDTH_CNTL);
         link_width_cntl &= ~LC_UPCONFIGURE_DIS;