_HID Deep Dive

Firmware-debug focused ACPI identity note.

June 10, 2026 2 min read

A device can be perfectly wired and fully powered, but if the OS cannot identify it, no driver will bind.

_HID is the ACPI object that gives the device its hardware identity. It may be a PNP ID such as PNP0C09 for an embedded controller, or an ACPI/PCI-style vendor identifier used by an OS driver.

Device (EC0)
{
    Name (_HID, EisaId ("PNP0C09"))
}

Item	Value	Note
PNP0C09	Embedded Controller	Common EC identity.
PNP0C0A	Control Method Battery	Battery device handled through ACPI methods.
ACPI0003	Power source device	Often used for AC adapter/power source.
PNP0C50	HID over I2C	Common touchpad/touchscreen class path.

Debug Diary

If a device is present in the namespace and _STA returns 0x0F, but no driver binds, check _HID and _CID. A single wrong character can move the device from a supported OS driver path to an unknown-device path.

_HID debug checklist

Confirm the namespace object exists in the OS dump.
Check _HID against the expected OS driver ID.
Check _CID for compatible fallback IDs.
Compare Windows and Linux binding behavior.
Verify that SKU-specific generation did not swap IDs between board variants.

Nội dung liên quan

Một số bài viết, ghi chú hoặc project có liên quan đến nội dung bạn vừa đọc.

Biến note thành bài viết hoàn chỉnh

Notes là nơi ghi nhanh khái niệm.

Đọc blog Xem notes khác

Debug Diary

_HID debug checklist

Related notes

Found this useful?

Nội dung liên quan

_CID Deep Dive

_UID Deep Dive

ACPI Architecture Overview

Biến note thành bài viết hoàn chỉnh