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-rw-r--r--shared-core/i915_irq.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/shared-core/i915_irq.c b/shared-core/i915_irq.c
index fd08b6e8..126f0379 100644
--- a/shared-core/i915_irq.c
+++ b/shared-core/i915_irq.c
@@ -406,6 +406,13 @@ u32 i915_get_vblank_counter(struct drm_device *dev, int plane)
if (i915_in_vblank(dev, pipe))
count++;
#endif
+ /* count may be reset by other driver(e.g. 2D driver),
+ we have no way to know if it is wrapped or resetted
+ when count is zero. do a rough guess.
+ */
+ if (count == 0 && dev->last_vblank[pipe] < dev->max_vblank_count/2)
+ dev->last_vblank[pipe] = 0;
+
return count;
}