Hi Craig,
On 08/04/2015 05:56 AM, Craig McQueen wrote:
I've written a udev rule to catch uevent "change" events, with the goal of
setting LED user/group/permissions whenever trigger settings are changed.
http://unix.stackexchange.com/a/202870/34376
However, I've noticed that a TRIGGER uevent "change" event is generated every
time an LED is turned off.
E.g. in one terminal:
udevadm monitor -p
In another terminal:
echo 0 > /sys/class/leds/beaglebone:green:usr3/brightness
The first terminal shows:
KERNEL[15446.374466] change /devices/leds/leds/beaglebone:green:usr3
(leds)
ACTION=change
DEVPATH=/devices/leds/leds/beaglebone:green:usr3
SEQNUM=39147
SUBSYSTEM=leds
TRIGGER=none
This behaviour is not ideal, because I really only want this uevent if the
trigger really has changed.
I presume this is due to these two lines in brightness_store() in led-class.c:
if (state == LED_OFF)
led_trigger_remove(led_cdev);
What would be the recommended way to improve this, so a TRIGGER uevent "change"
event is only generated if the trigger is actually reset to 'none' in this scenario?
I've noticed this on kernel 3.14.48 running on BeagleBone Black.
You can define your rule so that it would not be matched when
TRIGGER=none.
--
Best Regards,
Jacek Anaszewski
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