CP_RB_RPTR_WR    3097 drivers/gpu/drm/radeon/evergreen.c 	WREG32(CP_RB_RPTR_WR, 0);
CP_RB_RPTR_WR    2742 drivers/gpu/drm/radeon/r600.c 	WREG32(CP_RB_RPTR_WR, 0);