Re: [PATCH 3/3] hwmon: (acpi_power_meter) Check for 32-bit and 64-bit unknown ACPI values

[sashiko-bot@kernel.org]

> According to the ACPI specification (Section 10.4), ACPI Power Meter
> objects (_PMC capability fields, _PMM, _GHL, _PAI) report unknown or
> unavailable integer values using an integer with all bits set, which can
> be either U32_MAX (0xffffffff) or U64_MAX (0xffffffffffffffff) depending
> on the DSDT revision.
> 
> Currently, only hwmon_power_average checks both 32-bit and 64-bit
> unknown sentinels:
> - power1_cap_hyst_show() only compares res->caps.hysteresis against the
>   32-bit UNKNOWN_HYSTERESIS (0xffffffff), so a 64-bit U64_MAX sentinel
>   bypasses the check, overflows when multiplied by 1000, and emits a
>   bogus number instead of "unknown".
> - power1_accuracy_show() does not check for unknown sentinels at all,
>   formatting 0xffffffff as "4294967.295%".
> - power_meter_read() does not check min_avg_interval, max_avg_interval,
> [ ... ]
>   sampling_time is unknown.
> 
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Fixes: de584afa5e18 ("hwmon driver for ACPI 4.0 power meters")
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261031165447.1771473-1-linux@roeck-us.net?part=3