drm/amdgpu: clean framebuffer with GPU

CPU is not efficient to clean framebuffer especially under
virtualization, then loading driver takes long time which causes
timeout of mailbox handshake.
Signed-off-by: NPixel Ding <Pixel.Ding@amd.com>
Reviewed-by: NEdward O'Callaghan <funfunctor@folklore1984.net>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

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

@@ -147,7 +147,8 @@ static int amdgpufb_create_pinned_object(struct amdgpu_fbdev *rfbdev,
 	ret = amdgpu_gem_object_create(adev, aligned_size, 0,
 				       AMDGPU_GEM_DOMAIN_VRAM,
 				       AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED |
-				       AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS,
+				       AMDGPU_GEM_CREATE_VRAM_CONTIGUOUS |
+				       AMDGPU_GEM_CREATE_VRAM_CLEARED,
 				       true, &gobj);
 	if (ret) {
 		printk(KERN_ERR "failed to allocate framebuffer (%d)\n",
@@ -241,8 +242,6 @@ static int amdgpufb_create(struct drm_fb_helper *helper,
 	/* setup helper */
 	rfbdev->helper.fb = fb;
 
-	memset_io(abo->kptr, 0x0, amdgpu_bo_size(abo));
-
 	strcpy(info->fix.id, "amdgpudrmfb");
 
 	drm_fb_helper_fill_fix(info, fb->pitches[0], fb->format->depth);