Troubleshooting Reboot Issue After Shutdown on LS1046ARDB Board
Investigation on a rare reboot issue after shutdown occurring on LS1046ARDB board revealed that the SOC was reset, triggering a restart 4 times out of 46 shutdown instances. Despite disabling the watchdog driver, the problem persists, indicating a potential underlying issue. Further analysis is required to pinpoint the exact cause and resolve the unexpected reboots.
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Problem: In rare cases, shutdown h now causes a reboot after shutdown. The average frequency is about 4 times in 46 times. However, there is no regularity in the frequency of occurrence. Investigation method: Repeat login and shutdown using smart plug (set AC ON / OFF with timer) + teraterm macro. Also, observe the PORESET_B and RESET_REQ_B waveforms of the LS1046A with an oscilloscope. HW : LS1046ARDB SW : LSDK20.04 (kernel 19.04) uname -a Linux localhost 4.19.90-dirty #2 SMP PREEMPT Thu Dec 3 16:38:49 JST 2020 aarch64 aarch64 aarch64 GNU/Linux Confirmation result: We confirmed that the restart is occurring in shutdown. Reproduced 4 times out of 46 times. In that case restart is done after 7 seconds after shutdown. At that time, it was confirmed that RESET_REQ_B was issued by LS1046A. This revealed that the SOC was reset. I checked it with the kernel without the WDT driver of the Linux kernel, but the phenomenon does not change. It doesn't seem to be a problem with the WDT driver.
On the LS1046ARDB board, I confirmed the restart 4 times out of 46 shutdown times. Whenever a problem occurs, it will restart after 7 seconds. Waveform when restarting after shutdown [20:51:30] [ OK ] Reached target Final Step. [20:51:30] Starting Power-Off... [20:51:30] [ 18.673954] reboot: Power down [20:51:30] INFO: PSCI Power Domain Map: [20:51:30] INFO: Domain Node : Level 2, parent_node -1, State ON (0x0) [20:51:30] INFO: Domain Node : Level 1, parent_node 0, State ON (0x0) [20:51:30] INFO: CPU Node : MPID 0x0, parent_node 1, State ON (0x0) [20:51:30] INFO: CPU Node : MPID 0x1, parent_node 1, State ON (0x0) [20:51:30] INFO: CPU Node : MPID 0x2, parent_node 1, State ON (0x0) [20:51:30] INFO: CPU Node : MPID 0x3, parent_node 1, State ON (0x0) [20:51:37] INFO: RCW BOOT SRC is SD/EMMC [20:51:37] INFO: RCW BOOT SRC is SD/EMMC [20:51:37] INFO: esdhc_emmc_init [20:51:37] INFO: Card detected successfully [20:51:37] INFO: init done: [20:51:37] INFO: time base 45 ms [20:51:38] NOTICE: UDIMM 18ADF2G72AZ-2G6E1 [20:51:38] INFO: Time after parsing SPD 410 ms [20:51:38] INFO: Time before programming controller 413 ms [20:51:40] [20:51:40] NOTICE: 16 GB DDR4, 64-bit, CL=15, ECC on, CS0+CS1 [20:51:40] INFO: Time used by DDR driver 2054 ms [20:51:40] NOTICE: BL2: v1.5(debug):LSDK-20.04-update-290520-dirty [20:51:40] NOTICE: BL2: Built : 14:02:54, Dec 22 2020 [20:51:40] INFO: Configuring TrustZone Controller [20:51:40] INFO: Value of region base = ffe00000 [20:51:40] INFO: Value of region base = 1ffe00000 [20:51:40] INFO: Value of region base = fbe00000 [20:51:40] INFO: Value of region base = c80000000 [20:51:40] INFO: BL2: Doing platform setup RESET_REQ_B (ls1046 out) 7sec PORRESET_B (ls1046 in) It was confirmed that RESET_REQ_B as shown in the figure was output from LS1046A when it was restarted. In other words, it seems that this triggered a reset and restarted.
Disable LS1046ARDB Watchdog driver Default is ON, so turn it OFF Disable Watch Dog Timer Support in Kernel configure. After booting, make sure the / sys / class / watchdog folder does not exist. Make sure there is no watchdog process in ps aux. -Even if WDT is disabled, it rarely restarts. Isn't that a WDT issue? Kernel configure Device Drivers ---> [*] Watchdog Timer Support ---> <*> IMX2+ Watchdog Device tree IMX2 Watchdog Timer: arch/arm64/boot/dts/freescale/fsl-ls1046a.dtsi Only WDOG1 is used in LSDK20.04 of LS1046ARDB, and WDOG0,2,3,4 are unused. wdog0: watchdog@2ad0000 { compatible = "fsl,imx21-wdt"; reg = <0x0 0x2ad0000 0x0 0x10000>; interrupts = <GIC_SPI 83 IRQ_TYPE_LEVEL_HIGH>; clocks = <&clockgen 4 1>; big-endian; }; Source files drivers/watchdog/imx2_wdt.c
Appendix shutdown.ttl ; set username UsernamePrompt = 'login:' Username = 'root' PasswordPrompt = 'Password:' Password = 'root' CommandPrompt = 'root@localhost:~#' Command = 'shutdown -h now' WiFi Smart Plug AC LS1046A RDB PC V 100V console Adapter (teraterm) do ; login wait UsernamePrompt sendln Username Smart Life (iphone) wait PasswordPrompt sendln Password wait CommandPrompt sendln Command TECKIN SP11 loop 2minON->1minOFF->2minON .... repeat
