kernel version: 4.14.98
soc: imx8mm
We want to test the rs-485 and rs-232 functions on imx8mm, so we wrote a test program to send data and receive data with the PC
Because the official bsp does not support rs-485 function
We have added ioctl to enable rs-485 function
There are occasional errors in sending data before.
Refer to this link https://patchwork.kernel.org/patch/9799829/ It is normal to turn off the DMA function.
But this link is dead(The person who wrote this patch is from NXP )
We have now found that there is a problem of packet loss when testing data between each other through the test program
If the DMA is turned on, rs-232 is normal, but the rs-485 test will be stuck
Can you give us advice or there is a correct patch to enable rs-485 in kernel 4.14.98 for us to refer to
Attached is our rewritten driver and test program
