Hi all, FYI, starting with v5.7-rc1, kernel serial console now must be detached for the UARTs to idle. This has changed starting with commit a3cb39d258ef ("serial: core: Allow detach and attach serial device for console"). So folks may want to run something similar to the following on boot to detach serial console and idle the UARTs for PM. Regards, Tony 8< ------------- #!/bin/sh # Detach kernel serial console consoles=$(find /sys/bus/platform/devices/4*.serial/ -name console) for console in ${consoles}; do echo N > ${console} done # Configure PM runtime autosuspend uarts=$(find /sys/bus/platform/devices/4*.serial/power/ -type d) for uart in ${uarts}; do echo 1500 > ${uart}/autosuspend_delay_ms echo enabled > ${uart}/wakeup echo auto > ${uart}/control done # Configure wake-up from suspend uarts=$(find /sys/class/tty/tty[SO]*/power/ -type d 2>/dev/null) for uart in ${uarts}; do echo enabled > ${uart}/wakeup done # Enable off mode during idle if supported echo 1 > /sys/kernel/debug/pm_debug/enable_off_mode