drm/amdgpu/gmc10: adjust gart size for parts that support S/G display

For GMC 10 parts which support scatter/gather display (display
from system memory), we should allocate a larger gart size
to better handler larger displays.  This mirrors what we already
do for GMC 9 parts.

v2: fix typo (Alex)
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c

@@ -834,10 +834,21 @@ static int gmc_v10_0_mc_init(struct amdgpu_device *adev)
 		adev->gmc.visible_vram_size = adev->gmc.real_vram_size;
 
 	/* set the gart size */
-	if (amdgpu_gart_size == -1)
-		adev->gmc.gart_size = 512ULL << 20;
-	else
+	if (amdgpu_gart_size == -1) {
+		switch (adev->ip_versions[GC_HWIP][0]) {
+		default:
+			adev->gmc.gart_size = 512ULL << 20;
+			break;
+		case IP_VERSION(10, 3, 1):   /* DCE SG support */
+		case IP_VERSION(10, 3, 3):   /* DCE SG support */
+		case IP_VERSION(10, 3, 6):   /* DCE SG support */
+		case IP_VERSION(10, 3, 7):   /* DCE SG support */
+			adev->gmc.gart_size = 1024ULL << 20;
+			break;
+		}
+	} else {
 		adev->gmc.gart_size = (u64)amdgpu_gart_size << 20;
+	}
 
 	gmc_v10_0_vram_gtt_location(adev, &adev->gmc);