drm/amdgpu: Limit the maximum size of contiguous VRAM that can be encapsulated...

drm/amdgpu: Limit the maximum size of contiguous VRAM that can be encapsulated by an instance of DRM memory node

[Why]
Enable 1:1 mapping between VRAM of a DRM node and a scatterlist node

[How]
Ensure construction of DRM node to not exceed specified limit
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Ramesh Errabolu <Ramesh.Errabolu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c

@@ -473,6 +473,9 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
 	for (i = 0; pages_left >= pages_per_node; ++i) {
 		unsigned long pages = rounddown_pow_of_two(pages_left);
 
+		/* Limit maximum size to 2GB due to SG table limitations */
+		pages = min(pages, (2UL << (30 - PAGE_SHIFT)));
+
 		r = drm_mm_insert_node_in_range(mm, &nodes[i], pages,
 						pages_per_node, 0,
 						place->fpfn, lpfn,