C_028800_BACKFACE_ENABLE 1896 drivers/gpu/drm/radeon/evergreend.h #define   C_028800_BACKFACE_ENABLE                     0xFFFFFF7F
C_028800_BACKFACE_ENABLE 2344 drivers/gpu/drm/radeon/r600d.h #define   C_028800_BACKFACE_ENABLE                     0xFFFFFF7F