the hardware platform is NXP IMX6UL. the serial port driver is imx-uart. serial rs485conf is: SER_RS485_RTS_ON_SEND=high SER_RS485_RTS_AFTER_SEND=low delay_rts_before_send=0 delay_rts_after_send=0 the oscilloscope shows that after tx completes 2.5ms-5ms, the RTS pin is pulled down, but the opposite end returns data after tx completes 2ms
Hi
Hi, I also confirm RTS signal delay when transmitting. (same imx serial IP, on i.MX6ULL) In rs485, using an external chip (UM3483EESA) it corrupts received frame. (see oscilloscope capture) This is not consistent and only happens every 10-20 frames in my case. Thanks, Sebastien
Created attachment 304210 [details] RTS delay oscilloscope
Tested on 6.1.14 and 5.10.162
(In reply to slaveze from comment #4) > Tested on 6.1.14 and 5.10.162 According to my test, this problem only occurs when power management is turned on.
(In reply to YuDong Zhang from comment #5) > (In reply to slaveze from comment #4) > > Tested on 6.1.14 and 5.10.162 > According to my test, this problem only occurs when power management is > turned on. Tried disabling runtime pm: $ echo on > /sys/class/tty/ttymxc2/power/control But the behavior is still the same
(In reply to slaveze from comment #6) > (In reply to YuDong Zhang from comment #5) > > (In reply to slaveze from comment #4) > > > Tested on 6.1.14 and 5.10.162 > > According to my test, this problem only occurs when power management is > > turned on. > > Tried disabling runtime pm: > $ echo on > /sys/class/tty/ttymxc2/power/control > > But the behavior is still the same I recompile the kernel after turning off CONFIG_PM.
(In reply to slaveze from comment #6) > (In reply to YuDong Zhang from comment #5) > > (In reply to slaveze from comment #4) > > > Tested on 6.1.14 and 5.10.162 > > According to my test, this problem only occurs when power management is > > turned on. > > Tried disabling runtime pm: > $ echo on > /sys/class/tty/ttymxc2/power/control > > But the behavior is still the same It may be caused by other reasons, but I didn't investigate deeply.