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| author | David Brownell | 2008-02-08 13:21:22 +0100 |
|---|---|---|
| committer | Linus Torvalds | 2008-02-08 18:22:38 +0100 |
| commit | de5c9edee7a3cfdc6dd1a31c4794dc41ef3c70f9 (patch) | |
| tree | 2cc474aa124cd9efb8aa5b96072dd3fd2325148b /fs/pipe.c | |
| parent | Basic PWM driver for AVR32 and AT91 (diff) | |
| download | kernel-qcow2-linux-de5c9edee7a3cfdc6dd1a31c4794dc41ef3c70f9.tar.gz kernel-qcow2-linux-de5c9edee7a3cfdc6dd1a31c4794dc41ef3c70f9.tar.xz kernel-qcow2-linux-de5c9edee7a3cfdc6dd1a31c4794dc41ef3c70f9.zip | |
PWM LED driver
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>
Diffstat (limited to 'fs/pipe.c')
0 files changed, 0 insertions, 0 deletions