[PATCH 2/2] reuse-ro-scratch

[Chris Wilson]

---
 drivers/gpu/drm/i915/i915_gem_gtt.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index ed008b06aff5..5f8d63ff4449 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -1209,14 +1209,21 @@ static int gen8_init_scratch(struct i915_address_space *vm)
 {
 	int ret;
 
-	ret = setup_scratch_page(vm, __GFP_HIGHMEM);
-	if (ret)
-		return ret;
+	if (!vm->has_read_only) {
+		ret = setup_scratch_page(vm, __GFP_HIGHMEM);
+		if (ret)
+			return ret;
 
-	vm->scratch_pte = 
-		gen8_pte_encode(vm->scratch_page.daddr,
-				I915_CACHE_LLC,
-				PTE_READ_ONLY);
+		vm->scratch_pte =
+			gen8_pte_encode(vm->scratch_page.daddr,
+					I915_CACHE_LLC,
+					0);
+	} else {
+		vm->scratch_pte =
+			gen8_pte_encode(vm->i915->ggtt.vm.scratch_page.daddr,
+					I915_CACHE_LLC,
+					PTE_READ_ONLY);
+	}
 
 	vm->scratch_pt = alloc_pt(vm);
 	if (IS_ERR(vm->scratch_pt)) {
@@ -1293,7 +1300,8 @@ static void gen8_free_scratch(struct i915_address_space *vm)
 		free_pdp(vm, vm->scratch_pdp);
 	free_pd(vm, vm->scratch_pd);
 	free_pt(vm, vm->scratch_pt);
-	cleanup_scratch_page(vm);
+	if (vm->scratch_page.daddr)
+		cleanup_scratch_page(vm);
 }
 
 static void gen8_ppgtt_cleanup_3lvl(struct i915_address_space *vm,
-- 
2.19.1