drm/radeon: update wait_for_vblank for evergreen+

Properly wait for the next vblank region.  The previous
code didn't always wait long enough depending on the timing.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
index 124c193..f8a5b60 100644 (file)
--- a/drivers/gpu/drm/radeon/evergreen.c
+++ b/drivers/gpu/drm/radeon/evergreen.c
@@ -316,6 +316,27 @@ void evergreen_fix_pci_max_read_req_size(struct radeon_device *rdev)
        }
 }
 
+static bool dce4_is_in_vblank(struct radeon_device *rdev, int crtc)
+{
+       if (RREG32(EVERGREEN_CRTC_STATUS + crtc_offsets[crtc]) & EVERGREEN_CRTC_V_BLANK)
+               return true;
+       else
+               return false;
+}
+
+static bool dce4_is_counter_moving(struct radeon_device *rdev, int crtc)
+{
+       u32 pos1, pos2;
+
+       pos1 = RREG32(EVERGREEN_CRTC_STATUS_POSITION + crtc_offsets[crtc]);
+       pos2 = RREG32(EVERGREEN_CRTC_STATUS_POSITION + crtc_offsets[crtc]);
+
+       if (pos1 != pos2)
+               return true;
+       else
+               return false;
+}
+
 /**
  * dce4_wait_for_vblank - vblank wait asic callback.
  *
@@ -326,21 +347,28 @@ void evergreen_fix_pci_max_read_req_size(struct radeon_device *rdev)
  */
 void dce4_wait_for_vblank(struct radeon_device *rdev, int crtc)
 {
-       int i;
+       unsigned i = 0;
 
        if (crtc >= rdev->num_crtc)
                return;
 
-       if (RREG32(EVERGREEN_CRTC_CONTROL + crtc_offsets[crtc]) & EVERGREEN_CRTC_MASTER_EN) {
-               for (i = 0; i < rdev->usec_timeout; i++) {
-                       if (!(RREG32(EVERGREEN_CRTC_STATUS + crtc_offsets[crtc]) & EVERGREEN_CRTC_V_BLANK))
+       if (!(RREG32(EVERGREEN_CRTC_CONTROL + crtc_offsets[crtc]) & EVERGREEN_CRTC_MASTER_EN))
+               return;
+
+       /* depending on when we hit vblank, we may be close to active; if so,
+        * wait for another frame.
+        */
+       while (dce4_is_in_vblank(rdev, crtc)) {
+               if (i++ % 100 == 0) {
+                       if (!dce4_is_counter_moving(rdev, crtc))
                                break;
-                       udelay(1);
                }
-               for (i = 0; i < rdev->usec_timeout; i++) {
-                       if (RREG32(EVERGREEN_CRTC_STATUS + crtc_offsets[crtc]) & EVERGREEN_CRTC_V_BLANK)
+       }
+
+       while (!dce4_is_in_vblank(rdev, crtc)) {
+               if (i++ % 100 == 0) {
+                       if (!dce4_is_counter_moving(rdev, crtc))
                                break;
-                       udelay(1);
                }
        }
 }