drm/i915: Clear fence register on tiling stride change.

The fence register value also depends upon the stride of the object, so we
need to clear the fence if that is changed as well.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
[anholt: Added 8xx and 965 paths, and renamed the confusing
i915_gem_object_tiling_ok function to i915_gem_object_fence_offset_ok]
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 36 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 4f345414fe7c..174aef2d6481 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2162,7 +2162,6 @@ static void i830_write_fence_reg(struct drm_i915_fence_reg *reg)
 	val |= I830_FENCE_REG_VALID;
 
 	I915_WRITE(FENCE_REG_830_0 + (regnum * 4), val);
-
 }
 
 /**
@@ -2329,6 +2328,42 @@ i915_gem_clear_fence_reg(struct drm_gem_object *obj)
 }
 
 /**
+ * i915_gem_object_put_fence_reg - waits on outstanding fenced access
+ * to the buffer to finish, and then resets the fence register.
+ * @obj: tiled object holding a fence register.
+ *
+ * Zeroes out the fence register itself and clears out the associated
+ * data structures in dev_priv and obj_priv.
+ */
+int
+i915_gem_object_put_fence_reg(struct drm_gem_object *obj)
+{
+	struct drm_device *dev = obj->dev;
+	struct drm_i915_gem_object *obj_priv = obj->driver_private;
+
+	if (obj_priv->fence_reg == I915_FENCE_REG_NONE)
+		return 0;
+
+	/* On the i915, GPU access to tiled buffers is via a fence,
+	 * therefore we must wait for any outstanding access to complete
+	 * before clearing the fence.
+	 */
+	if (!IS_I965G(dev)) {
+		int ret;
+
+		i915_gem_object_flush_gpu_write_domain(obj);
+		i915_gem_object_flush_gtt_write_domain(obj);
+		ret = i915_gem_object_wait_rendering(obj);
+		if (ret != 0)
+			return ret;
+	}
+
+	i915_gem_clear_fence_reg (obj);
+
+	return 0;
+}
+
+/**
  * Finds free space in the GTT aperture and binds the object there.
  */
 static int