CP_RB_RPTR_WR     486 drivers/gpu/drm/radeon/evergreend.h #define	CP_RB_RPTR_WR					0xC108
CP_RB_RPTR_WR     205 drivers/gpu/drm/radeon/r600d.h #define	CP_RB_RPTR_WR					0xC108
CP_RB_RPTR_WR     358 drivers/gpu/drm/radeon/rv770d.h #define	CP_RB_RPTR_WR					0xC108