fdMonitor only works sporadically

[jyijyi]

do you see problem with generic API like open(),read(),write() to control the UART?

Does it relate to this issue where data is received during reboot?

Kernel BUG at /usr/src/kernel/kernel/time/timer.c:806!

I cannot reproduce this in mangoh green board with UART1 in data mode. (already send data continuously with baud rate 921600 on other side since boot up) Can you load this “yocto_wp76xx.4k_msm_serial_hs.cwe” on top of R16.0.01 and see if problem still happens at your side?