mcp251x_spi_write
mcp251x_spi_write(spi, 3);
mcp251x_spi_write(spi, 4);
return mcp251x_spi_write(spi, 4);
mcp251x_spi_write(spi, TXBDAT_OFF + len);
mcp251x_spi_write(priv->spi, 1);
ret = mcp251x_spi_write(spi, 1);