Re: [REGRESSION] Kernel reboots unexpectdely on i.MX8X when Cortex-M4 is running and it was started by U-Boot bootaux

[Hiago De Franco]

On Fri, Apr 04, 2025 at 11:17:13AM -0300, Hiago De Franco wrote:
> #regzbot introduced: 4f6c983261
> 
> Hi Peng and all,
> 
> Commit 4f6c9832613b ("genpd: imx: scu-pd: initialize is_off according to
> HW state") introduced a regression where the Kernel reboots unexpectedly
> (without any warnings, crashes or errors) when the Cortex-M4 was loaded
> and running by U-Boot, using the bootaux command:
> 
> # load mmc 0:2 ${loadaddr} /home/root/hello_world.bin
> # bootaux ${loadaddr} 0
> # boot
> 
> This is a simple hello world binary that prints a message into the
> M40.UART0 pin (demo from NXP MCUXpresso).
> 
> Before this commit, everything worked as expected, Linux boots fine and
> the HMP core keeps running and printing messages to the UART. After the
> commit, the kernel reboots at the beggining of the boot process. The
> only relevant message is printed by U-Boot after reset:
> 
> "Reset cause: SCFW fault reset"
> 
> This commit was bisectabled, the same device tree, u-boot version, and
> SCFW versions were used. Reverting this commit fixes the issues.
> 
> For testing purposes, I created the following patch which also fixes the
> issue:
> 
> diff --git a/drivers/pmdomain/imx/scu-pd.c b/drivers/pmdomain/imx/scu-pd.c
> index 38f3cdd21042..0477b3fb4991 100644
> --- a/drivers/pmdomain/imx/scu-pd.c
> +++ b/drivers/pmdomain/imx/scu-pd.c
> @@ -539,6 +539,9 @@ imx_scu_add_pm_domain(struct device *dev, int idx,
>                 return NULL;
>         }
> 
> +       if (strstr("cm40", sc_pd->name) != NULL)
> +               is_off = true;
> +
>         ret = pm_genpd_init(&sc_pd->pd, NULL, is_off);
>         if (ret) {
>                 dev_warn(dev, "failed to init pd %s rsrc id %d",
> 
> 
> Test Environment:
> - Hardware: Colibri iMX8DX 1GB with Colbiri Evaluation Board.
> - U-Boot Version: 2024.04
> - U-Boot Build info:
> 	SCFW 83624b99, SECO-FW c9de51c0, IMX-MKIMAGE 4622115c, ATF 7c64d4e
> 
> The issue is not present on: v6.5
> 
> The real root cause is still unclear to me. Anybody has any ideas? I am
> happy to share more details if needed.

Hello everyone, as this introduced a regression, should I send a revert
for 4f6c983261? Or any ideas that might help fix this issue?

> 
> Cheers,
> Hiago.

Cheers,
Hiago.