Commit d19a8a70 authored Apr 06, 2014 by Russell King Committed by Bryan Wu May 08, 2014

leds: leds-pwm: implement PWM inversion



Some PWM outputs are wired such that the LED they're controlling is
connected to supply rather than ground.  These PWMs may not support
output inversion, or when they do, disabling the PWM may set the
PWM output low, causing a "brightness" value of zero to turn the LED
fully on.

The platform data for this driver already indicates that this was
thought about, and we have the "active_low" property there already.
However, the implementation for this is missing.

Add the trivial implementation for this feature.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

parent b795e6d9

drivers/leds/leds-pwm.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -69,6 +69,10 @@ static void led_pwm_set(struct led_classdev *led_cdev,

		duty *= brightness;
		do_div(duty, max);

		if (led_dat->active_low)
		duty = led_dat->period - duty;

		led_dat->duty = duty;

		if (led_dat->can_sleep)

Admin message