X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=Documentation%2Fleds-class.txt;h=8fd5ca2ae32dde4d9eb27722942a5d099f4afbc3;hb=8365388827663bd6fb773e3623ed9023c0f82b1d;hp=18860ad9935a7876746c00660f36b9fd90529499;hpb=0013b23d66a2768f5babbb0ea9f03ab067a990d8;p=safe%2Fjmp%2Flinux-2.6 diff --git a/Documentation/leds-class.txt b/Documentation/leds-class.txt index 18860ad..8fd5ca2 100644 --- a/Documentation/leds-class.txt +++ b/Documentation/leds-class.txt @@ -1,3 +1,4 @@ + LED handling under Linux ======================== @@ -5,10 +6,10 @@ If you're reading this and thinking about keyboard leds, these are handled by the input subsystem and the led class is *not* needed. In its simplest form, the LED class just allows control of LEDs from -userspace. LEDs appear in /sys/class/leds/. The brightness file will -set the brightness of the LED (taking a value 0-255). Most LEDs don't -have hardware brightness support so will just be turned on for non-zero -brightness settings. +userspace. LEDs appear in /sys/class/leds/. The maximum brightness of the +LED is defined in max_brightness file. The brightness file will set the brightness +of the LED (taking a value 0-max_brightness). Most LEDs don't have hardware +brightness support so will just be turned on for non-zero brightness settings. The class also introduces the optional concept of an LED trigger. A trigger is a kernel based source of led events. Triggers can either be simple or @@ -59,7 +60,7 @@ Hardware accelerated blink of LEDs Some LEDs can be programmed to blink without any CPU interaction. To support this feature, a LED driver can optionally implement the -blink_set() function (see ). If implemeted, triggers can +blink_set() function (see ). If implemented, triggers can attempt to use it before falling back to software timers. The blink_set() function should return 0 if the blink setting is supported, or -EINVAL otherwise, which means that LED blinking will be handled by software.