drm/amdgpu: add common support for dimgrey_cavefish

Add external id and set clock gating for dimgrey_cavefish.
Signed-off-by: Tao Zhou <tao.zhou1@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Jiansong Chen <Jiansong.Chen@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -891,6 +891,11 @@ static int nv_common_early_init(void *handle)
 		adev->pg_flags = AMD_PG_SUPPORT_GFX_PG;
 		adev->external_rev_id = adev->rev_id + 0x01;
 		break;
+	case CHIP_DIMGREY_CAVEFISH:
+		adev->cg_flags = 0;
+		adev->pg_flags = 0;
+		adev->external_rev_id = adev->rev_id + 0x3c;
+		break;
 	default:
 		/* FIXME: not supported yet */
 		return -EINVAL;
@@ -1118,6 +1123,7 @@ static int nv_common_set_clockgating_state(void *handle,
 	case CHIP_NAVI12:
 	case CHIP_SIENNA_CICHLID:
 	case CHIP_NAVY_FLOUNDER:
+	case CHIP_DIMGREY_CAVEFISH:
 		adev->nbio.funcs->update_medium_grain_clock_gating(adev,
 				state == AMD_CG_STATE_GATE);
 		adev->nbio.funcs->update_medium_grain_light_sleep(adev,