[Bug 212939] New: thinkpad_acpi reports balanced in /sys/firmware/acpi/platform_profile when thermal throttling

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=212939

            Bug ID: 212939
           Summary: thinkpad_acpi reports balanced in
                    /sys/firmware/acpi/platform_profile when thermal
                    throttling
           Product: Drivers
           Version: 2.5
    Kernel Version: 5.12
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Platform_x86
          Assignee: drivers_platform_x86@kernel-bugs.osdl.org
          Reporter: jwrdegoede@fedoraproject.org
        Regression: No

The platform-profile interface implemented by thinkpad_acpi and available
through the /sys/firmware/acpi/platform_profile, should reflect the last user
selected value.

Where the user-selected value is either the last value written to the sysfs
file, or selected through Fn + L / M / H. Key combinations.

When in performance mode and the CPU temperature goes over 97 degrees Celcius
the embedded-controller will temporarily drop back to balanced mode to give the
CPU a chance to cool-down a bit. This is fine as an internal implementation
detail, but this should not be visible inside the
/sys/firmware/acpi/platform_profile interface (1).

Having it visible here causes problems for userspace. E.g. the selected profile
visible in the power-panel of gnome-control-center can be seen jumping between
Performance and Balanced all the time, as if the user is pressing Fn + H, Fn +
M, Fn + H, ... all the time.

Note this is not so much a kernel bug as that it seems to be a problem with the
firmware interface which thinkpad_acpi is using. As such this
bugzilla.kernel.org entry is purely meant for tracking this issue, IOW a kernel
fix for this will not be forthcoming, but hopefully we can get Lenovo to fix
this on the firmware side.


1) The information about the thermal limits leading to temporary dropping back
to balanced mode could be exported elsewhere, like how lapmode is exported
through: /sys/bus/platform/devices/thinkpad_acpi/dytc_lapmode

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