+ struct drm_i915_private *dev_priv = dev->dev_private;
+ int pipestat_reg = (pipe == 0 ? PIPEASTAT : PIPEBSTAT);
+
+ /* Wait for vblank interrupt bit to set */
+ if (wait_for((I915_READ(pipestat_reg) &
+ PIPE_VBLANK_INTERRUPT_STATUS) == 0,
+ 50, 0))
+ DRM_DEBUG_KMS("vblank wait timed out\n");
+}
+
+/**
+ * intel_wait_for_vblank_off - wait for vblank after disabling a pipe
+ * @dev: drm device
+ * @pipe: pipe to wait for
+ *
+ * After disabling a pipe, we can't wait for vblank in the usual way,
+ * spinning on the vblank interrupt status bit, since we won't actually
+ * see an interrupt when the pipe is disabled.
+ *
+ * So this function waits for the display line value to settle (it
+ * usually ends up stopping at the start of the next frame).
+ */
+void intel_wait_for_vblank_off(struct drm_device *dev, int pipe)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ int pipedsl_reg = (pipe == 0 ? PIPEADSL : PIPEBDSL);
+ unsigned long timeout = jiffies + msecs_to_jiffies(100);
+ u32 last_line;
+
+ /* Wait for the display line to settle */
+ do {
+ last_line = I915_READ(pipedsl_reg) & DSL_LINEMASK;
+ mdelay(5);
+ } while (((I915_READ(pipedsl_reg) & DSL_LINEMASK) != last_line) &&
+ time_after(timeout, jiffies));
+
+ if (time_after(jiffies, timeout))
+ DRM_DEBUG_KMS("vblank wait timed out\n");