Watchdog OPTEE Panic when stopping in u-boot

[Ivan_Radmilo_Bytelab]

Hi,

I have enabled iwdg2 in tf-a, uboot (PV="v2023.10-stm32mp-r1") , optee (version 4.0.0-stm32mp) and linux kernel(ver. v6.6-stm32mp) device trees for STM32MP133F. iwdg is enabled in non-secure world only.

&iwdg2 {
status = "okay";

/* USER CODE BEGIN iwdg2 */
timeout-sec = <60>;
/* USER CODE END iwdg2 */
};

When stopping in u-boot there are 2 scenarios that manifest as watchdog caused reset.

1. First scenario is when the system is just stopped and inactive in u-boot.
2. Second scenario is when running mtest in u-boot. (mtest writes and reads to addresses from 0xc0000000 to 0xc4000000; excluding the end address) 

With op-tee watchdog reset there is Panic stack unwind:

E/TC:0   Panic 'Watchdog' at /usr/src/debug/optee-os-stm32mp/4.0.0-stm32mp-r1/core/drivers/stm32_iwdg.c:228 <stm32_iwdg_it_handler> 

E/TC:0   TEE load address @ 0xce000000 

E/TC:0   Call stack: 

E/TC:0    0xce00a1d4 print_kernel_stack at /usr/src/debug/optee-os-stm32mp/4.0.0-stm32mp-r1/core/arch/arm/kernel/unwind_arm32.c:109 

E/TC:0    0xce086f08 __do_panic at /usr/src/debug/optee-os-stm32mp/4.0.0-stm32mp-r1/core/kernel/panic.c:88 

E/TC:0    0xce03902c stm32_iwdg_it_handler at /usr/src/debug/optee-os-stm32mp/4.0.0-stm32mp-r1/core/drivers/stm32_iwdg.c:228 

E/TC:0    0xce0821ac interrupt_call_handlers at /usr/src/debug/optee-os-stm32mp/4.0.0-stm32mp-r1/core/kernel/interrupt.c:91 

E/TC:0    0xce02e8d0 gic_native_itr_handler at /usr/src/debug/optee-os-stm32mp/4.0.0-stm32mp-r1/core/drivers/gic.c:659 

E/TC:0    0xce02e900 interrupt_main_handler at /usr/src/debug/optee-os-stm32mp/4.0.0-stm32mp-r1/core/drivers/gic.c:670 

E/TC:0    0xce000388 vector_fiq_entry at tmp-glibc/work/mcm_ng-oe-linux-gnueabi/optee-os-stm32mp/4.0.0-stm32mp-r1/git/core/arch/arm/kernel/thread_optee_smc_a32.S:93  

And this is another example of watchdog reboot where the system is stopped in u-boot (debug traces are enabled with additional watchdog reset debug trace added).

16:54:45:688 -> stm32mp-wdt watchdog@5a002000: IWDG reset
16:54:46:688 -> stm32mp-wdt watchdog@5a002000: IWDG reset
16:54:47:688 -> stm32mp-wdt watchdog@5a002000: IWDG reset
16:54:48:688 -> stm32mp-wdt watchdog@5a002000: IWDG reset
...
...
17:19:47:718 -> stm32mp-wdt watchdog@5a002000: IWDG reset
17:19:48:718 -> stm32mp-wdt watchdog@5a002000: IWDG reset
17:21:16:953 -> NOTICE:  CPU: STM32MP133F Rev.Y
17:21:16:956 -> NOTICE:  Model: STMicroelectronics custom STM32CubeMX board - openstlinux-6.6-yocto-scarthgap-mpu-v24.11.06
17:21:16:978 -> NOTICE:  Reset reason (0x204):
17:21:16:981 -> INFO:      IWDG2 Reset (rst_iwdg2)

After some time the u-boot stops refreshing watchdog and there is subsequent reset.

Can you please suggest how to debug this issue and if there is something wrong with described iwdg2 configuration?