drm/radeon: fix DP mode validation

[firefly-linux-kernel-4.4.55.git] / drivers / gpu / drm / radeon / radeon_kms.c

diff --git a/drivers/gpu/drm/radeon/radeon_kms.c b/drivers/gpu/drm/radeon/radeon_kms.c
index 0ec6fcca16d3b12b898d8c9c036ab330cdc47226..d290a8a09036e9d28aa78332f7f2d22ee46ec0e2 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_kms.c
@@ -755,6 +755,8 @@ void radeon_driver_preclose_kms(struct drm_device *dev,
  */
 u32 radeon_get_vblank_counter_kms(struct drm_device *dev, int crtc)
 {
+       int vpos, hpos, stat;
+       u32 count;
        struct radeon_device *rdev = dev->dev_private;
 
        if (crtc < 0 || crtc >= rdev->num_crtc) {
@@ -762,7 +764,53 @@ u32 radeon_get_vblank_counter_kms(struct drm_device *dev, int crtc)
                return -EINVAL;
        }
 
-       return radeon_get_vblank_counter(rdev, crtc);
+       /* The hw increments its frame counter at start of vsync, not at start
+        * of vblank, as is required by DRM core vblank counter handling.
+        * Cook the hw count here to make it appear to the caller as if it
+        * incremented at start of vblank. We measure distance to start of
+        * vblank in vpos. vpos therefore will be >= 0 between start of vblank
+        * and start of vsync, so vpos >= 0 means to bump the hw frame counter
+        * result by 1 to give the proper appearance to caller.
+        */
+       if (rdev->mode_info.crtcs[crtc]) {
+               /* Repeat readout if needed to provide stable result if
+                * we cross start of vsync during the queries.
+                */
+               do {
+                       count = radeon_get_vblank_counter(rdev, crtc);
+                       /* Ask radeon_get_crtc_scanoutpos to return vpos as
+                        * distance to start of vblank, instead of regular
+                        * vertical scanout pos.
+                        */
+                       stat = radeon_get_crtc_scanoutpos(
+                               dev, crtc, GET_DISTANCE_TO_VBLANKSTART,
+                               &vpos, &hpos, NULL, NULL,
+                               &rdev->mode_info.crtcs[crtc]->base.hwmode);
+               } while (count != radeon_get_vblank_counter(rdev, crtc));
+
+               if (((stat & (DRM_SCANOUTPOS_VALID | DRM_SCANOUTPOS_ACCURATE)) !=
+                   (DRM_SCANOUTPOS_VALID | DRM_SCANOUTPOS_ACCURATE))) {
+                       DRM_DEBUG_VBL("Query failed! stat %d\n", stat);
+               }
+               else {
+                       DRM_DEBUG_VBL("crtc %d: dist from vblank start %d\n",
+                                     crtc, vpos);
+
+                       /* Bump counter if we are at >= leading edge of vblank,
+                        * but before vsync where vpos would turn negative and
+                        * the hw counter really increments.
+                        */
+                       if (vpos >= 0)
+                               count++;
+               }
+       }
+       else {
+           /* Fallback to use value as is. */
+           count = radeon_get_vblank_counter(rdev, crtc);
+           DRM_DEBUG_VBL("NULL mode info! Returned count may be wrong.\n");
+       }
+
+       return count;
 }
 
 /**