ACPI Namespace

This is an example of the display-related namespace on an ACPI system:

GPE          // ACPI General-purpose HW event
    _L0x     // Notify(VGA, 0x80) to tell OSPM of the event, when user presses
             // the hot key to switch the output status of the monitor.
             // Notify(VGA, 0x81) to tell the event to OSPM, when there are any
             // changes on the sub-devices for the VGA controller

SB
|- PCI
    |- VGA              // Define the VGA controller in the namespace
        |- \_PS0 / PR0
        |- \_PS1 / PR1
        |- \_PS3
        |- \_DOS        // Method to control display output switching
        |- \_DOD        // Method to retrieve information about child output devices
        |- \_ROM        // Method to retrieve the ROM image for this device
        |- \_GPD        // Method for determining which VGA device will post
        |- \_SPD        // Method for controlling which VGA device will post
        |- \_VPO        // Method for determining the post options
        |- CRT          // Child device CRT
            |- \_ADR    // Hardware ID for this device
            |- \_DDC    // Get EDID information from the monitor device
            |- \_DCS    // Get current hardware status
            |- \_DGS    // Query desired hardware active \ inactive state
            |- \_DSS    // Set hardware active \ inactive state
            |- \_PS0  \
            |- \_PS1    - Power methods
            |- \_PS2    - for the output device
            |- \_PS3  /
        |- LCD          // Child device LCD
            |- \_ADR    // Hardware ID for this device
            |- \_DDC    // Get EDID information from the monitor device
            |- \_DCS    // Get current hardware status
            |- \_DGS    // Query desired hardware active \ inactive state
            |- \_DSS    // Set hardware active \ inactive state
            |- \_BCL    // Brightness control levels
            |- \_BCM    // Brightness control method
            |- \_BQC    // Brightness Query Current Level
            |- \_PS0  \
            |- \_PS1    - Power methods
            |- \_PS2    - for the output device
            |- \_PS3  /
        |- TV           // Child Device TV
            |- \_ADR    // Hardware ID for this device
            |- \_DDC    // Get EDID information from the monitor device
            |- \_DCS    // Get current hardware status
            |- \_DGS    // Query desired hardware active \ inactive state
            |- \_DSS    // Set hardware active \ inactive state

The LCD device represents the built-in output device. Mobile PCs will always have a built-in LCD display, but desktop systems that have a built-in graphics adapter generally don’t have a built-in output device.