I need your help or some advice in the following problem:
I work with i.MX 6UltraLite EVK – development board for iMX6ul processor.
Prepared Linux image based on Buildroot and configured by defconfig for this board.
Linux kernel version : v4.9.11 (from official freescale git repo).
My goal is realization of UART in RS485 mode with RTS inactivation time no higher than 20us after TX is finished.
At now, driver has deactivation time for about 20 ms after TX is finished.
I test this at simply program:
open file descriptor to tty
use send POSIX [write] gunction to send data
close file descriptor
Current version of driver I am working on : http://elixir.free-electrons.com/linux/v4.9.11/source/drivers/tty/serial/imx.c
I have realized that this driver is for several types of processors of one family with similar register map, but I haven’t found in code any particular comments on specific realization, except some comments in probe function.
How to modify the driver code for fast (as much as could be possible) inactivation RTS gpio after TX is finished.
Thank, you for help.