BACK_PORCH_SHIFT  102 drivers/gpu/drm/zte/zx_vou_regs.h #define BACK_PORCH_MASK			(0x7ff << BACK_PORCH_SHIFT)
BACK_PORCH_SHIFT  147 drivers/gpu/drm/zte/zx_vou_regs.h #define BACK_PORCH(x)	(((x) << BACK_PORCH_SHIFT) & BACK_PORCH_MASK)