I'm useing imx6ul runing the kernel linux3.14.38, when I read data from the /dev/ttymxc3 the other side connect with a MCU. When imx6ul send a data to the MCU it will return data within 5ms . But I have a test , If send data less than 171ms, the ttymxc3 can't read data. So I can't read return data from MCU. In imx6ul, I use select to read data. Where i can modify that let me read data whin 5ms?