drm/radeon: update wait_for_vblank for evergreen+

commit 10257a6d8359c41407eb26b7ad7bf710a7e00155 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 36 insertions, 8 deletions

diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
index 1b0a4eca922a..4157c33516af 100644
--- a/drivers/gpu/drm/radeon/evergreen.c
+++ b/drivers/gpu/drm/radeon/evergreen.c
@@ -105,6 +105,27 @@ 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.
  *
@@ -115,21 +136,28 @@ 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);
                 }
         }
 }