linux-kernel - Re: [PATCH v4 7/7] thermal: core: Record PSCR before hw_protection

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Message-ID: <726c6ffc-a8d4-4328-a849-2d59f3a0a1c9@linaro.org>
Date: Wed, 12 Mar 2025 16:35:51 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Oleksij Rempel <o.rempel@...gutronix.de>,
 Sebastian Reichel <sre@...nel.org>,
 Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc: kernel@...gutronix.de, linux-kernel@...r.kernel.org,
 Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
 "Rafael J. Wysocki" <rafael@...nel.org>, Zhang Rui <rui.zhang@...el.com>,
 Lukasz Luba <lukasz.luba@....com>, linux-pm@...r.kernel.org,
 Søren Andersen <san@...v.dk>
Subject: Re: [PATCH v4 7/7] thermal: core: Record PSCR before
 hw_protection_shutdown()

Hi Oleksij,

On 06/03/2025 10:38, Oleksij Rempel wrote:
> Enhance the thermal core to record the Power State Change Reason (PSCR)
> prior to invoking hw_protection_shutdown(). This change integrates the
> PSCR framework with the thermal subsystem, ensuring that reasons for
> power state changes, such as overtemperature events, are stored in a
> dedicated non-volatile memory (NVMEM) cell.
> 
> This 'black box' recording is crucial for post-mortem analysis, enabling
> a deeper understanding of system failures and abrupt shutdowns,
> especially in scenarios where PMICs or watchdog timers are incapable of
> logging such events.  The recorded data can be utilized during system
> recovery routines in the bootloader or early kernel stages of subsequent
> boots, significantly enhancing system diagnostics, reliability, and
> debugging capabilities.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> ---
>   drivers/thermal/thermal_core.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 2328ac0d8561..af4e9cf22bf6 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -16,6 +16,7 @@
>   #include <linux/kdev_t.h>
>   #include <linux/idr.h>
>   #include <linux/thermal.h>
> +#include <linux/pscrr.h>
>   #include <linux/reboot.h>
>   #include <linux/string.h>
>   #include <linux/of.h>
> @@ -380,6 +381,8 @@ static void thermal_zone_device_halt(struct thermal_zone_device *tz, bool shutdo
>   
>   	dev_emerg(&tz->device, "%s: critical temperature reached\n", tz->type);
>   
> +	set_power_state_change_reason(PSCR_OVERTEMPERATURE);
> +
>   	if (shutdown)
>   		hw_protection_shutdown(msg, poweroff_delay_ms);
>   	else

In the future could you add me as recipient to the series instead of 
this one ? so I can get more context.

Given there are no so much hw_protection_shutdown() users in the kernel, 
it could be more interesting to change the function to receive a enum 
pscr_reason and then in the hw_protection_shutdown() call 
pscrr_reason_to_str().

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