[PATCH 07/11] drm/i915: Rebind bo if currently bound with incorrect alignment.

[Chris Wilson <chris@chris-wilson.co.uk>]

Whilst pinning the buffer, check that that its current alignment
matches the requested alignment. If it does not, rebind.

This should clear up any final render errors whilst resuming,
for reference:

  Bug 27070 - [i915] Page table errors with empty ringbuffer
  https://bugs.freedesktop.org/show_bug.cgi?id=27070

  Bug 15502 -  render error detected, EIR: 0x00000010
  https://bugzilla.kernel.org/show_bug.cgi?id=15502

  Bug 13844 -  i915 error: "render error detected"
  https://bugzilla.kernel.org/show_bug.cgi?id=13844

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
---
 drivers/gpu/drm/i915/i915_gem.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 6425c2a..a5ca959 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4164,6 +4164,17 @@ i915_gem_object_pin(struct drm_gem_object *obj, uint32_t alignment)
 	BUG_ON(obj_priv->pin_count == DRM_I915_GEM_OBJECT_MAX_PIN_COUNT);
 
 	i915_verify_inactive(dev, __FILE__, __LINE__);
+
+	if (obj_priv->gtt_space != NULL) {
+		if (alignment == 0)
+			alignment = i915_gem_get_gtt_alignment(obj);
+		if (obj_priv->gtt_offset & (alignment - 1)) {
+			ret = i915_gem_object_unbind(obj);
+			if (ret)
+				return ret;
+		}
+	}
+
 	if (obj_priv->gtt_space == NULL) {
 		ret = i915_gem_object_bind_to_gtt(obj, alignment);
 		if (ret)
-- 
1.7.1