acpi_fan_speed_valid(9)

🎀 NAME 🎀

okay bestie, welcome to acpi_fan_speed_valid(9) from the Kernel API Manual — this is literally the page for “Check if fan speed value is valid” ✨💅

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✨ SYNOPSIS ✨

bool acpi_fan_speed_valid (u64 speed );

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🫶 ARGUMENTS 🫶

• speed — Speed value returned by the ACPI firmware. That’s the value getting the vibe check 💅

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💖 DESCRIPTION 💖

Check if the fan speed value returned by the ACPI firmware is valid. That’s the whole assignment, bestie ✨.

This function is necessary as ACPI firmware implementations can return 0xFFFFFFFF to signal that the ACPI fan does not support speed reporting. iykyk, that’s the “no speed reporting for you” placeholder 🫠.

Additionally, some buggy ACPI firmware implementations return a value larger than the 32-bit integer value defined by the ACPI specification when using placeholder values 😭. Such invalid values are also detected by this function. Not me trusting firmware, never 💀.

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🔥 RETURN 🔥

True if the fan speed value is valid, false otherwise. That’s it — valid speed? iconic 👑. Invalid? caught in 4K 📸.

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🌈 SEE ALSO 🌈

• Kernel file ./drivers/acpi/fan.h — go read it, bestie 🫶
• acpi_fan_power_valid(9) — the other ACPI fan validity check, slay ✨

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This cutie came from ./drivers/acpi, dated October 2026, and it’s the acpi_fan_speed_valid(9) manual page. Mwah, bye bestie 💋🎀