diff options
| -rw-r--r-- | drivers/gpu/drm/i915/intel_display.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 11a3394f5fe..3fc767bcbaa 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -990,6 +990,22 @@ void intel_wait_for_vblank(struct drm_device *dev, int pipe) struct drm_i915_private *dev_priv = dev->dev_private; int pipestat_reg = (pipe == 0 ? PIPEASTAT : PIPEBSTAT); + /* Clear existing vblank status. Note this will clear any other + * sticky status fields as well. + * + * This races with i915_driver_irq_handler() with the result + * that either function could miss a vblank event. Here it is not + * fatal, as we will either wait upon the next vblank interrupt or + * timeout. Generally speaking intel_wait_for_vblank() is only + * called during modeset at which time the GPU should be idle and + * should *not* be performing page flips and thus not waiting on + * vblanks... + * Currently, the result of us stealing a vblank from the irq + * handler is that a single frame will be skipped during swapbuffers. + */ + I915_WRITE(pipestat_reg, + I915_READ(pipestat_reg) | PIPE_VBLANK_INTERRUPT_STATUS); + /* Wait for vblank interrupt bit to set */ if (wait_for((I915_READ(pipestat_reg) & PIPE_VBLANK_INTERRUPT_STATUS), |