I got the answer. union { uint64_t reg; struct { uint64_t i_row_wid:10; uint64_t i_col_high:9; uint64_t reserved0:13; uint64_t o_row_wid:10; uint64_t o_col_high:9; uint64_t reserved1:13; } data; } image_size; so the input image width could not exceed 1024,when i try 120 x 640 image is OK. so the input size could not bigger than 256x1024?