garbage collect i915_vblank_swap.

3 files changed, 5 insertions, 26 deletions

diff --git a/sys/dev/pci/drm/i915_drv.c b/sys/dev/pci/drm/i915_drv.c
index 0e6d416519a..fba0392c0b3 100644
--- a/sys/dev/pci/drm/i915_drv.c
+++ b/sys/dev/pci/drm/i915_drv.c
@@ -123,7 +123,11 @@ inteldrm_ioctl(struct drm_device *dev, u_long cmd, caddr_t data,
 		case DRM_IOCTL_I915_GET_VBLANK_PIPE:
 			return (i915_vblank_pipe_get(dev, data, file_priv));
 		case DRM_IOCTL_I915_VBLANK_SWAP:
-			return (i915_vblank_swap(dev, data, file_priv));
+			/*
+			 * removed due to being racy. Userland falls back
+			 * correctly when it errors out
+			 */
+			return (EINVAL);
 		}
 	}
 
diff --git a/sys/dev/pci/drm/i915_drv.h b/sys/dev/pci/drm/i915_drv.h
index 99616d9d682..f3d97659c33 100644
--- a/sys/dev/pci/drm/i915_drv.h
+++ b/sys/dev/pci/drm/i915_drv.h
@@ -242,8 +242,6 @@ extern int i915_emit_irq(struct drm_device * dev);
 extern int i915_enable_vblank(struct drm_device *dev, int crtc);
 extern void i915_disable_vblank(struct drm_device *dev, int crtc);
 extern u32 i915_get_vblank_counter(struct drm_device *dev, int crtc);
-extern int i915_vblank_swap(struct drm_device *dev, void *data,
-			    struct drm_file *file_priv);
 extern void i915_user_irq_get(struct drm_device *dev);
 extern void i915_user_irq_put(struct drm_device *dev);
 
diff --git a/sys/dev/pci/drm/i915_irq.c b/sys/dev/pci/drm/i915_irq.c
index 379f8e1e9b3..e1f4d5119c9 100644
--- a/sys/dev/pci/drm/i915_irq.c
+++ b/sys/dev/pci/drm/i915_irq.c
@@ -398,29 +398,6 @@ int i915_vblank_pipe_get(struct drm_device *dev, void *data,
 	return 0;
 }
 
-/*
- * Schedule buffer swap at given vertical blank.
- */
-int i915_vblank_swap(struct drm_device *dev, void *data,
-		     struct drm_file *file_priv)
-{
-	/* The delayed swap mechanism was fundamentally racy, and has been
-	 * removed.  The model was that the client requested a delayed flip/swap
-	 * from the kernel, then waited for vblank before continuing to perform
-	 * rendering.  The problem was that the kernel might wake the client
-	 * up before it dispatched the vblank swap (since the lock has to be
-	 * held while touching the ringbuffer), in which case the client would
-	 * clear and start the next frame before the swap occurred, and   
-	 * flicker would occur in addition to likely missing the vblank.
-	 *
-	 * In the absence of this ioctl, userland falls back to a correct path
-	 * of waiting for a vblank, then dispatching the swap on its own.
-	 * Context switching to userland and back is plenty fast enough for
-	 * meeting the requirements of vblank swapping.
-	 */
-	return (EINVAL);
-}
-
 /* drm_dma.h hooks
 */
 void i915_driver_irq_preinstall(struct drm_device * dev)