drm/i915: Combine pinning with setting to the display plane

We need to perform a few operations in order to move the object into the
display plane (where it can be accessed coherently by the display
engine) that are important for future safety to forbid whilst pinned. As a
result, we want to need to perform some of the operations before pinning,
but some are required once we have been bound into the GTT. So combine
the pinning performed by all the callers with set_to_display_plane(), so
this complication is contained within the single function.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 26 insertions, 11 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e6915072ba72..8a439f0c21f5 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3095,40 +3095,55 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
 }
 
 /*
- * Prepare buffer for display plane. Use uninterruptible for possible flush
- * wait, as in modesetting process we're not supposed to be interrupted.
+ * Prepare buffer for display plane (scanout, cursors, etc).
+ * Can be called from an uninterruptible phase (modesetting) and allows
+ * any flushes to be pipelined (for pageflips).
+ *
+ * For the display plane, we want to be in the GTT but out of any write
+ * domains. So in many ways this looks like set_to_gtt_domain() apart from the
+ * ability to pipeline the waits, pinning and any additional subtleties
+ * that may differentiate the display plane from ordinary buffers.
  */
 int
-i915_gem_object_set_to_display_plane(struct drm_i915_gem_object *obj,
+i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
+				     u32 alignment,
 				     struct intel_ring_buffer *pipelined)
 {
-	uint32_t old_read_domains;
+	u32 old_read_domains, old_write_domain;
 	int ret;
 
-	/* Not valid to be called on unbound objects. */
-	if (obj->gtt_space == NULL)
-		return -EINVAL;
-
 	ret = i915_gem_object_flush_gpu_write_domain(obj);
 	if (ret)
 		return ret;
 
-
-	/* Currently, we are always called from an non-interruptible context. */
 	if (pipelined != obj->ring) {
 		ret = i915_gem_object_wait_rendering(obj);
 		if (ret)
 			return ret;
 	}
 
+	/* As the user may map the buffer once pinned in the display plane
+	 * (e.g. libkms for the bootup splash), we have to ensure that we
+	 * always use map_and_fenceable for all scanout buffers.
+	 */
+	ret = i915_gem_object_pin(obj, alignment, true);
+	if (ret)
+		return ret;
+
 	i915_gem_object_flush_cpu_write_domain(obj);
 
+	old_write_domain = obj->base.write_domain;
 	old_read_domains = obj->base.read_domains;
+
+	/* It should now be out of any other write domains, and we can update
+	 * the domain values for our changes.
+	 */
+	BUG_ON((obj->base.write_domain & ~I915_GEM_DOMAIN_GTT) != 0);
 	obj->base.read_domains |= I915_GEM_DOMAIN_GTT;
 
 	trace_i915_gem_object_change_domain(obj,
 					    old_read_domains,
-					    obj->base.write_domain);
+					    old_write_domain);
 
 	return 0;
 }