[Bug 222107] New: hp-wmi: fan1_input and fan2_input always 0 on OmniBook 7 17-dc (8D9C)

[Bug 222107] New: hp-wmi: fan1_input and fan2_input always 0 on OmniBook 7 17-dc (8D9C)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=222107

            Bug ID: 222107
           Summary: hp-wmi: fan1_input and fan2_input always 0 on OmniBook
                    7 17-dc (8D9C)
           Product: Drivers
           Version: 2.5
    Kernel Version: 7.2.7-arch1-1
          Hardware: Intel
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: Platform_x86
          Assignee: drivers_platform_x86@kernel-bugs.osdl.org
          Reporter: jaeho2025@gmail.com
                CC: krishna.chomal108@gmail.com
        Regression: No

Created attachment 311036
  --> https://bugzilla.kernel.org/attachment.cgi?id=311036&action=edit
acpidump of HP OmniBook 7 17-dc0xxx (board 8D9C)

Separate report for board 8D9C as requested on bug 221385.

HP OmniBook 7 Laptop 17-dc0xxx
Board: HP 8D9C, version 45.36
BIOS: F.10

Symptom: hp-wmi fan1_input and fan2_input always return 0 RPM while
the fans are spinning. acpi_fan (PNP0C0B:00) reports the real speed.

I tested the GM fan queries in a small module. 0x11 (fan speed),
0x10 (fan count) and 0x26 (max) return PASS with a zero payload.
0x4c still returns data.

Attached: full acpidump. I will attach the EC dump (ec_sys, ec0/io) as a second
attachment.

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[Bug 222107] hp-wmi: fan1_input and fan2_input always 0 on OmniBook 7 17-dc (8D9C)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=222107

--- Comment #1 from Jae (jaeho2025@gmail.com) ---
Created attachment 311037
  --> https://bugzilla.kernel.org/attachment.cgi?id=311037&action=edit
EC dump

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[Bug 222107] hp-wmi: fan1_input and fan2_input always 0 on OmniBook 7 17-dc (8D9C)

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=222107

--- Comment #2 from Krishna Chomal (krishna.chomal108@gmail.com) ---
Hi Jae,

I took a look at your ACPI tables, and they seem consistent with your findings.
The relevant HP WMI methods appear to be stub implementations, which would
explain why the fan-related queries return PASS with a zero payload.

This suggests that the issue is likely on the firmware side rather than a
Linux-specific problem. If the firmware does not implement these methods,
hp-wmi has no meaningful fan-speed data to retrieve through this interface. If
I am not wrong, HP's official software on Windows would also not support fan
read/control behaviour.

For now, it looks like relying on acpi_fan is the best option. Proper support
through hp-wmi would likely require a firmware update from HP that implements
the relevant WMI methods.

Sorry I don't have a better solution!

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