drm/i915: FB backing gem obj should reside in LMEM

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

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

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]
v5:
  i915_gem_object_is_lmem is used for detecting the obj mem type. [Matt]

cc: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: NRamalingam C <ramalingam.c@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191105144414.30470-1-ramalingam.c@intel.com

drivers/gpu/drm/i915/gem/i915_gem_domain.c

@@ -12,6 +12,7 @@
 #include "i915_gem_ioctls.h"
 #include "i915_gem_object.h"
 #include "i915_vma.h"
+#include "i915_gem_lmem.h"
 
 static void __i915_gem_object_flush_for_display(struct drm_i915_gem_object *obj)
 {
@@ -419,11 +420,16 @@ 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);
 
+	/* Frame buffer must be in LMEM (no migration yet) */
+	if (HAS_LMEM(i915) && !i915_gem_object_is_lmem(obj))
+		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
@@ -435,7 +441,7 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
 	 * with that bit in the PTE to main memory with just one PIPE_CONTROL.
 	 */
 	ret = i915_gem_object_set_cache_level(obj,
-					      HAS_WT(to_i915(obj->base.dev)) ?
+					      HAS_WT(i915) ?
 					      I915_CACHE_WT : I915_CACHE_NONE);
 	if (ret)
 		return ERR_PTR(ret);