STM32H7_SPI_CFG1_DSIZE
cfg1_clrb |= STM32H7_SPI_CFG1_DSIZE;
cfg1_setb |= FIELD_PREP(STM32H7_SPI_CFG1_DSIZE, bpw);
stm32_spi_set_bits(spi, STM32H7_SPI_CFG1, STM32H7_SPI_CFG1_DSIZE);
max_bpw = FIELD_GET(STM32H7_SPI_CFG1_DSIZE, cfg1) + 1;