Re: [PATCH] arm: mach-k3: am625: Unlock MMR registers again

Sverdlin, Alexander
2026-01-12T07:31:45Z

On Fri, 2025-08-15 at 09:02 -0700, Daniel Schultz wrote:
> The watchdog requires to have the MCU ESM error source enabled to
> trigger a system reboot. When booting HS-SE (security enforced)
> devices, the MMR registers are locked again and all write commands
> are simply ignored.
>
> Unlock the MMR registers again to successfully enable the MCU ESM
> source.
>
> Signed-off-by: Daniel Schultz <d.schultz@phytec.de>

Reviewed-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>

> ---
>  arch/arm/mach-k3/am62x/am625_init.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/arch/arm/mach-k3/am62x/am625_init.c b/arch/arm/mach-k3/am62x/am625_init.c
> index a422919fab1..498bbe45b38 100644
> --- a/arch/arm/mach-k3/am62x/am625_init.c
> +++ b/arch/arm/mach-k3/am62x/am625_init.c
> @@ -84,6 +84,9 @@ static void ctrl_mmr_unlock(void)
>
>  static __maybe_unused void enable_mcu_esm_reset(void)
>  {
> + /* CTRLMMR_MCU_RST registers are locked again on HS-SE devices */
> + mmr_unlock(MCU_CTRL_MMR0_BASE, 6);
> +
>   /* Set CTRLMMR_MCU_RST_CTRL:MCU_ESM_ERROR_RST_EN_Z  to '0' (low active) */
>   u32 stat = readl(CTRLMMR_MCU_RST_CTRL);

--
Alexander Sverdlin
Siemens AG