[Intel-gfx] [PATCH 2/2] drm/i915: FB backing gem obj should reside in LMEM

[Ramalingam C]

If Local memory is supported by hardware, we want framebuffer backing
gem objects from local memory.

pin_to_display is failed, if the backing obj is not from LMEM.

This is developed on top of LMEM Basics
https://patchwork.freedesktop.org/series/67350/

v2:
  memory regions are correctly assigned to obj->memory_regions [tvrtko]
  migration failure is reported as debug log [Tvrtko]
v3:
  Migration is dropped. only error is reported [Daniel]
  mem region check is move to pin_to_display [Chris]
v4:
  s/dev_priv/i915 [chris]

cc: Matthew Auld <matthew.auld at intel.com>
Signed-off-by: Ramalingam C <ramalingam.c at intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_domain.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_domain.c b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
index 55c3ab59e3aa..6bf211784f73 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_domain.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
@@ -419,11 +419,19 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
 				     const struct i915_ggtt_view *view,
 				     unsigned int flags)
 {
+	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 	struct i915_vma *vma;
 	int ret;
 
 	assert_object_held(obj);
 
+	/* GEM Obj for frame buffer is expected to be in LMEM. */
+	if (HAS_LMEM(i915))
+		if (obj->mm.region->type != INTEL_LMEM) {
+			DRM_DEBUG_KMS("OBJ is not from LMEM\n");
+			return ERR_PTR(-EINVAL);
+		}
+
 	/*
 	 * The display engine is not coherent with the LLC cache on gen6.  As
 	 * a result, we make sure that the pinning that is about to occur is
-- 
2.20.1