@validate(addr=int, cmd=int)<EOL><INDENT>def read_block_data(self, addr, cmd):<DEDENT>
<EOL>self._set_addr(addr)<EOL>data = ffi.new("<STR_LIT>")<EOL>if SMBUS.i2c_smbus_access(self._fd,<EOL>int2byte(SMBUS.I2C_SMBUS_READ),<EOL>ffi.cast("<STR_LIT>", cmd),<EOL>SMBUS.I2C_SMBUS_BLOCK_DATA,<EOL>data):<EOL><INDENT>raise IOError(ffi.errno)<EOL><DEDENT>return smbus_data_to_list(data)<EOL>
read_block_data(addr, cmd) -> results

        Perform SMBus Read Block Data transaction.