73 lines
2.3 KiB
Org Mode
73 lines
2.3 KiB
Org Mode
-*- org -*-
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It is somehow important to provide consistent interface to the
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userland. LED devices have one problem there, and that is naming of
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directories in /sys/class/leds. It would be nice if userland would
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just know right "name" for given LED function, but situation got more
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complex.
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Anyway, if backwards compatibility is not an issue, new code should
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use one of the "good" names from this list, and you should extend the
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list where applicable.
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Legacy names are listed, too; in case you are writing application that
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wants to use particular feature, you should probe for good name, first,
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but then try the legacy ones, too.
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Notice there's a list of functions in include/dt-bindings/leds/common.h .
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* Gamepads and joysticks
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Game controllers may feature LEDs to indicate a player number. This is commonly
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used on game consoles in which multiple controllers can be connected to a system.
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The "player LEDs" are then programmed with a pattern to indicate a particular
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player. For example, a game controller with 4 LEDs, may be programmed with "x---"
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to indicate player 1, "-x--" to indicate player 2 etcetera where "x" means on.
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Input drivers can utilize the LED class to expose the individual player LEDs
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of a game controller using the function "player".
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Note: tracking and management of Player IDs is the responsibility of user space,
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though drivers may pick a default value.
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Good: "input*:*:player-{1,2,3,4,5}
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* Keyboards
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Good: "input*:*:capslock"
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Good: "input*:*:scrolllock"
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Good: "input*:*:numlock"
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Legacy: "shift-key-light" (Motorola Droid 4, capslock)
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Set of common keyboard LEDs, going back to PC AT or so.
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Legacy: "tpacpi::thinklight" (IBM/Lenovo Thinkpads)
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Legacy: "lp5523:kb{1,2,3,4,5,6}" (Nokia N900)
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Frontlight/backlight of main keyboard.
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Legacy: "button-backlight" (Motorola Droid 4)
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Some phones have touch buttons below screen; it is different from main
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keyboard. And this is their backlight.
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* Sound subsystem
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Good: "platform:*:mute"
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Good: "platform:*:micmute"
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LEDs on notebook body, indicating that sound input / output is muted.
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* System notification
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Legacy: "status-led:{red,green,blue}" (Motorola Droid 4)
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Legacy: "lp5523:{r,g,b}" (Nokia N900)
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Phones usually have multi-color status LED.
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* Power management
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Good: "platform:*:charging" (allwinner sun50i)
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* Screen
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Good: ":backlight" (Motorola Droid 4)
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