I'm trying to build a patch for this issue, but I encountered some problems.
1. The permission of the file in sysfs is 0644, so gsd(gnome-settings-daemon) should have root privilege to access the file.
-rw-r--r-- 1 root root 4096 Jan 13 17:04 /sys/class/leds/dell-laptop::touchpad/brightness
But the gsd run as a normal user privilege, so it don't have the permission to control the touchpad LED.
I'm wondering how user space application deals with this kind of issue.
2. After system recovered from S3, the touchpad LED won't turn on again. Is there any way that gsd can know the system recovered from S3 and reset the LED status? I can discuss with the driver maintainer if there is no way to know that.