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This is a LED driver using the PWM on newer SOCs from Atmel; brightness is controlled by changing the PWM duty cycle. So for example if you've set up two leds labeled "pwm0" and "pwm1": echo 0 > /sys/class/leds/pwm2/brightness # off (0%) echo 80 > /sys/class/leds/pwm2/brightness echo 255 > /sys/class/leds/pwm2/brightness # on (100%) Note that "brightness" here isn't linear; maybe that should change. Going from 4 to 8 probably doubles perceived brightness, while 244 to 248 is imperceptible. This is mostly intended to be a simple example of PWM, although it's realistic since LCD backlights are often driven with PWM to conserve battery power (and offer brightness options). Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Richard Purdie <rpurdie@rpsys.net> Cc: Andrew Victor <linux@maxim.org.za> Cc: Nicolas Ferre <nicolas.ferre@atmel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| .. | ||
| Kconfig | ||
| led-class.c | ||
| led-core.c | ||
| led-triggers.c | ||
| leds-ams-delta.c | ||
| leds-atmel-pwm.c | ||
| leds-clevo-mail.c | ||
| leds-cm-x270.c | ||
| leds-cobalt-qube.c | ||
| leds-cobalt-raq.c | ||
| leds-corgi.c | ||
| leds-gpio.c | ||
| leds-h1940.c | ||
| leds-hp6xx.c | ||
| leds-locomo.c | ||
| leds-net48xx.c | ||
| leds-s3c24xx.c | ||
| leds-spitz.c | ||
| leds-tosa.c | ||
| leds-wrap.c | ||
| leds.h | ||
| ledtrig-heartbeat.c | ||
| ledtrig-ide-disk.c | ||
| ledtrig-timer.c | ||
| Makefile | ||