Hello,
I have been working with kernel 4.19.94, enter standby and resume with UART (console) and it was working fine:
root@BeagleBone:~# uname -a
Linux BeagleBone 4.19.94-ti-r74 #1bullseye SMP PREEMPT Tue Jun 27 20:55:24 UTC 2023 armv7l GNU/Linux
root@BeagleBone:~# echo enabled > /sys/devices/platform/ocp/44e09000.serial/power/wakeup
root@BeagleBone:~# echo enabled > /sys/devices/platform/ocp/44e09000.serial/tty/ttyS0/power/wakeup
root@BeagleBone:~# cat /sys/devices/platform/ocp/44e09000.serial/power/wakeup
enabled
root@BeagleBone:~# cat /sys/devices/platform/ocp/44e09000.serial/tty/ttyS0/power/wakeup
enabled
root@BeagleBone:~#
root@BeagleBone:~# dmesg -w &
[1] 1099
root@BeagleBone:~#
root@BeagleBone:~#
root@BeagleBone:~# echo standby > /sys/power/state
[ 393.065310] PM: suspend entry (shallow)
[ 393.065328] PM: Syncing filesystems … done.
[ 393.066755] Freezing user space processes … (elapsed 0.002 seconds) done.
[ 393.068946] OOM killer disabled.
[ 393.068952] Freezing remaining freezable tasks … (elapsed 0.001 seconds) done.
[ 393.070433] Suspending console(s) (use no_console_suspend to debug)
[ 393.219718] Disabling non-boot CPUs …
[ 393.219762] pm33xx pm33xx: PM: Successfully put all powerdomains to target state
[ 393.219762] PM: Wakeup source UART
[ 393.246511] net eth0: initializing cpsw version 1.12 (0)
[ 393.322096] SMSC LAN8710/LAN8720 4a101000.mdio:00: attached PHY driver [SMSC LAN8710/LAN8720] (mii_bus:phy_addr=4a101000.mdio:00, irq=POLL)
[ 393.446455] OOM killer enabled.
[ 393.446490] Restarting tasks … done.
[ 393.471057] PM: suspend exit
Now I upgraded to kernel 6.1.80 and I can not resume from standby mode:
Linux BeagleBone 6.1.80-ti-r34 #1bullseye SMP PREEMPT Fri Mar 22 11:06:21 UTC 2024 armv7l GNU/Linux
root@BeagleBone:~# echo enabled > /sys/devices/platform/ocp/44c00000.interconnect/44c00000.interconnect:segment@200000/44e09050.target-module/44e09000.serial/power/wakeup
root@BeagleBone:~# echo enabled > /sys/devices/platform/ocp/44c00000.interconnect/44c00000.interconnect:segment@200000/44e09050.target-module/44e09000.serial/tty/ttyS0/power/wakeup
root@BeagleBone:~# cat /sys/devices/platform/ocp/44c00000.interconnect/44c00000.interconnect:segment@200000/44e09050.target-module/44e09000.serial/power/wakeup
enabled
root@BeagleBone:~# cat /sys/devices/platform/ocp/44c00000.interconnect/44c00000.interconnect:segment@200000/44e09050.target-module/44e09000.serial/tty/ttyS0/power/wakeup
enabled
root@BeagleBone:~#
root@BeagleBone:~# dmesg -w &
[1] 568
root@BeagleBone:~#
root@BeagleBone:~# echo standby > /sys/power/state
[ 129.598380] PM: suspend entry (shallow)
[ 129.598629] Filesystems sync: 0.000 seconds
At this point I press keys on the console but system nevers wakes up.
Do we need to do something else with the new kernel in order to enable the standby/resume feature?
Best regards and thank you
Angel