drm/amdgpu: Fixup hw vblank counter/ts for new drm_update_vblank_count() (v3)

[people/ms/linux.git] / drivers / gpu / drm / amd / amdgpu / amdgpu_kms.c

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
index 1618e2294a16056171458998ed65e62a83583774..e23843f4d877be7813a1574db0f855847f9aa591 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
@@ -611,13 +611,59 @@ void amdgpu_driver_preclose_kms(struct drm_device *dev,
 u32 amdgpu_get_vblank_counter_kms(struct drm_device *dev, unsigned int pipe)
 {
        struct amdgpu_device *adev = dev->dev_private;
+       int vpos, hpos, stat;
+       u32 count;
 
        if (pipe >= adev->mode_info.num_crtc) {
                DRM_ERROR("Invalid crtc %u\n", pipe);
                return -EINVAL;
        }
 
-       return amdgpu_display_vblank_get_counter(adev, pipe);
+       /* 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 (adev->mode_info.crtcs[pipe]) {
+               /* Repeat readout if needed to provide stable result if
+                * we cross start of vsync during the queries.
+                */
+               do {
+                       count = amdgpu_display_vblank_get_counter(adev, pipe);
+                       /* Ask amdgpu_get_crtc_scanoutpos to return vpos as
+                        * distance to start of vblank, instead of regular
+                        * vertical scanout pos.
+                        */
+                       stat = amdgpu_get_crtc_scanoutpos(
+                               dev, pipe, GET_DISTANCE_TO_VBLANKSTART,
+                               &vpos, &hpos, NULL, NULL,
+                               &adev->mode_info.crtcs[pipe]->base.hwmode);
+               } while (count != amdgpu_display_vblank_get_counter(adev, pipe));
+
+               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",
+                                     pipe, 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 = amdgpu_display_vblank_get_counter(adev, pipe);
+               DRM_DEBUG_VBL("NULL mode info! Returned count may be wrong.\n");
+       }
+
+       return count;
 }
 
 /**