diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
index 65483f0a44c1..620fddde4c4d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
@@ -324,16 +324,13 @@ int amdgpu_gtt_mgr_init(struct amdgpu_device *adev, uint64_t gtt_size)
 {
 	struct amdgpu_gtt_mgr *mgr = &adev->mman.gtt_mgr;
 	struct ttm_resource_manager *man = &mgr->manager;
-	uint64_t start, size;
 
 	man->use_tt = true;
 	man->func = &amdgpu_gtt_mgr_func;
 
 	ttm_resource_manager_init(man, &adev->mman.bdev, gtt_size);
 
-	start = AMDGPU_GTT_MAX_TRANSFER_SIZE * AMDGPU_GTT_NUM_TRANSFER_WINDOWS;
-	size = (adev->gmc.gart_size >> PAGE_SHIFT) - start;
-	drm_mm_init(&mgr->mm, start, size);
+	drm_mm_init(&mgr->mm, 0, adev->gmc.gart_size >> PAGE_SHIFT);
 	spin_lock_init(&mgr->lock);
 
 	ttm_set_driver_manager(&adev->mman.bdev, TTM_PL_TT, &mgr->manager);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
index 8af0aab7608c..f927b793c395 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
@@ -40,7 +40,6 @@
 #define __AMDGPU_PL_NUM	(TTM_PL_PRIV + 6)
 
 #define AMDGPU_GTT_MAX_TRANSFER_SIZE	512
-#define AMDGPU_GTT_NUM_TRANSFER_WINDOWS	3
 
 extern const struct attribute_group amdgpu_vram_mgr_attr_group;
 extern const struct attribute_group amdgpu_gtt_mgr_attr_group;