ディスプレイ制御のソースを表示

[[Category:ディスプレイ制御]]
[[Category:ノートパソコン]]
ディスプレイ制御プロトコルは、ビデオリンクを介した補助信号または追加のバスによるディスプレイの制御を可能にします。最も基本的な機能は電源と[[バックライト]]管理であり、後者は主にノートパソコンや一部のテレビ画面でサポートされていますが、スタンドアロンのコンピュータモニターではまだ普及していません。

制御可能な機能は一般に実装に大きく依存します。また、重複する機能を持つ多数のディスプレイ制御プロトコルとその実装が使用されています。

{{Accuracy|{{ic|video}} is a [[Users and groups#Pre-systemd groups|pre-systemd group]], access to hardware is generally managed by [[udev]].}}

以下およびリンクされた記事に記載されているほとんどのツールについては、ユーザーを {{ic|video}} [[ユーザーグループ]]に追加することでユーザーアクセスを許可できます。

== Hardware-only ==

These limited implementations can mostly be found in older laptops. Hardware-only meaning there is no software interface for backlight control so the user can only use preset keyboard keys/combinations or a dedicated rotating-type/sliding-type switch or a knob. Old CRT computer monitors also had hardware brightness control.

== Vendor-specific ==

Vendor-specific implementations and also some related tools are well presented in [[Backlight]]. Vendor-specific [[ACPI modules|ACPI]] implementations and [[Backlight#setpci|GPU hacks]] without a standard [[kernel]] interface also fall in this limited category, as do external displays with a custom protocol over UART/USB and similar. These are typically not supported in [[desktop environments]].

== ACPI ==

[[ACPI modules|ACPI-module implementations]] are only found in laptops and PCs with integrated displays (such as AIOs), but partially standardized and accessible from software. ACPI implementations with {{ic|/sys/class/backlight}} interface are usually well-supported in [[desktop environment]]s, but no other display control features are available.

== DPMS ==

While omnipresent in computer hardware and well-supported in software for a long time, the [[Display Power Management Signaling]] only allows for display power management into 2-4 states, but no finer [[backlight]] or other control. In TV setups it can switch the panel state at best, but it cannot wake or suspend a TV.

== (E-)DDC/CI ==

The [[Backlight#External monitors|(Enhanced) Display Data Channel / Command Interface]] interface carries ''M''onitor ''C''ontrol ''C''ommand ''S''et (MCCS) over [[I2C]] and can complement or even replace DPMS in computer hardware. Even though DDC 1.0 was published in 1994 and E-DDC 1.0 in 1999, the feature has only started to appear in standalone computer monitors in 2010s. Besides power and [[Backlight#External monitors|backlight]] management it has an extensive command set for controlling all display settings supported in its controller. {{Pkg|ddcutil}} (GUI: {{AUR|ddcui}}) and {{AUR|ddccontrol}} (GUI: {{AUR|gddccontrol}}) are the tools to look at. For backlight control it is possible to create {{ic|/sys/class/backlight}} interface with {{AUR|ddcci-driver-linux-dkms}}, which enables desktop integration, but still needs mainlining.

== eDP v1.2 ==

Embedded Display Port (eDP) introduced a display control protocol in version 1.2 working through the auxiliary DisplayPort channel, superseding DDC/CI in embedded/laptop displays.[https://www.vesa.org/wp-content/uploads/2010/12/DisplayPort-DevCon-Presentation-eDP-Dec-2010-v3.pdf]

== HDMI-CEC ==

[[HDMI-CEC|HDMI - Consumer Electronics Control]] is an additional I2C-like, but very slow bus for waking and controlling standalone enduser devices such as TVs. Available from HDMI 1.0, it uses pin 13 in a HDMI connector and it needs a tiny bit of additional hardware to drive the bus. Somehow it is typically not supported in PC GPUs so additional hardware is needed. Specialised [[HDMI-CEC#CEC adapter|USB-CEC adapters]] are not cheap and abundant, a better alternative is to use [[kernel]] driver which uses auxiliary channel of [[HDMI-CEC#Tunneling over DisplayPort|DisplayPort for HDMI-CEC]] signalling, but it works only with [https://docs.kernel.org/admin-guide/media/cec.html#displayport-to-hdmi-adapters-with-working-cec a select few] DP-to-HDMI adapters. On the other hand [[HDMI-CEC#Native CEC|native HDMI-CEC]] support is [https://docs.kernel.org/admin-guide/media/cec.html#supported-hardware-in-mainline normal] in ARM single-board computers and certain Android devices. Desktop HDMI-CEC integration in Arch Linux is currently [[HDMI-CEC#Software setup|manual]], but manageable for simple setups such as waking TV from standby. Supported in userspace primarily through {{ic|cec-ctl}} from {{Pkg|v4l-utils}} or alternatively with {{ic|cec-client}} from {{Pkg|libcec}}.