Le Potato and Sweet Potato feature many wakeup sources.
One of the sources is the serial UART used for debugging. If the board is placed in suspend or shutdown mode, the UART RX GPIO can be pulled down to wake up the system. This can be done by sending space keys.
dxue@debian-12-aml-s905x-cc:~$ sudo systemctl suspend
dxue@debian-12-aml-s905x-cc:~$ [ 638.008872] stmmac_set_mac: writing to MAC_CTRL_REG 61cc00
[ 638.010849] meson8b-dwmac c9410000.ethernet end0: Link is Down
[ 638.100318] PM: suspend entry (deep)
[ 638.190377] Filesystems sync: 0.087 seconds
[ 638.194967] Freezing user space processes
[ 638.200530] Freezing user space processes completed (elapsed 0.003 seconds)
[ 638.205527] OOM killer disabled.
[ 638.209078] Freezing remaining freezable tasks
[ 638.214459] Freezing remaining freezable tasks completed (elapsed 0.001 seconds)
[ 638.219215] printk: Suspending console(s) (use no_console_suspend to debug)
bl30 get wakeup sources!
process command 00000006
bl30 enter suspend!
cpu clk suspend rate 1000000000
suspend_counter: 5
Enter ddr suspend
dmc sec unlock
not first time suspend
ddr suspend time: 3704us
gp0 pll
process command 00000001
CEC cfg:0x0000
set vddee to 0x035c mv
08915d0000000000cec reset
irq aoir
irq ao gpio0
irq gpio0
**PRESS SPACE KEY**
irq ao gpio0
exit_reason:0x06
set vddee to 0x03e8 mv
set vcck to 0x0460 mv
gp0 pll
Enter ddr resume
ddr resume time: 344us
dmc sec lock
cfg15 63b00200
cfg15 63b00200
cpu clk resume rate 1000000000
[ 638.261286] Disabling non-boot CPUs ...
[ 638.263431] psci: CPU3 killed (polled 0 ms)
[ 638.266840] psci: CPU2 killed (polled 0 ms)
[ 638.270915] psci: CPU1 killed (polled 4 ms)
[ 638.272538] Enabling non-boot CPUs ...
[ 638.273774] Detected VIPT I-cache on CPU1
[ 638.273870] CPU1: Booted secondary processor 0x0000000001 [0x410fd034]
[ 638.274732] CPU1 is up
[ 638.275915] Detected VIPT I-cache on CPU2
[ 638.276013] CPU2: Booted secondary processor 0x0000000002 [0x410fd034]
[ 638.276890] CPU2 is up
[ 638.278221] Detected VIPT I-cache on CPU3
[ 638.278324] CPU3: Booted secondary processor 0x0000000003 [0x410fd034]
[ 638.279633] CPU3 is up
[ 638.281730] rc rc0: sw decoder init
[ 638.841228] xhci-hcd xhci-hcd.1.auto: xHC error in resume, USBSTS 0x411, Reinit
[ 638.841255] usb usb1: root hub lost power or was reset
[ 638.841865] xhci-hcd xhci-hcd.1.auto: USB3 root hub has no ports
[ 639.107662] usb 1-1: reset high-speed USB device number 2 using xhci-hcd
[ 639.507838] OOM killer enabled.
[ 639.509624] Restarting tasks ... done.
[ 639.513240] random: crng reseeded on system resumption
[ 639.518390] PM: suspend exit
[ 639.552790] meson8b-dwmac c9410000.ethernet end0: Register MEM_TYPE_PAGE_POOL RxQ-0
[ 639.619589] meson8b-dwmac c9410000.ethernet end0: PHY [mdio_mux-0.1:08] driver [Meson GXL Internal PHY] (irq=27)
[ 639.637842] meson8b-dwmac c9410000.ethernet end0: No Safety Features support found
[ 639.641401] stmmac_set_mac: writing to MAC_CTRL_REG 61840c
[ 639.646839] meson8b-dwmac c9410000.ethernet end0: PTP not supported by HW
[ 639.653597] meson8b-dwmac c9410000.ethernet end0: configuring for phy/rmii link mode
[ 641.459908] meson8b-dwmac c9410000.ethernet end0: Link is Up - 100Mbps/Full - flow control rx/tx