At the kernel >= 3.4 (samsung-laptop module) there has been appeared a Samsung RV520 laptop support (Product Name: RV420/RV520/RV720/E3530/S3530/E3420/E3520). But the trouble with brightness adjustment exists: When I try to change the brightness level, the maximum brightness limit becomes very low (~20...30%). Then, when I press <Fn + Up> (brightness up) further, a backlight is blinking for a short time, but the brightness level doesn't change. <Fn + Down> (brightness down) works well. If I unplug the supply cable and then plug it back, the brightness level becomes maximum (100%). But after decreasing the brightness level the problem with <Fn + Up> repeats again. > # cat /sys/devices/platform/samsung/backlight/samsung/max_brightness > 8 > > # echo 8 > /sys/devices/platform/samsung/backlight/samsung/actual_brightness > -bash: /sys/devices/platform/samsung/backlight/samsung/actual_brightness: > Permission denied But the backlight is blinking for a short time, if I execute this: > # echo 8 > /sys/devices/platform/samsung/backlight/samsung/brightness I've updated kernel up to 3.5.0 ― the situation is the same: after the brightness level decreasing it's not possible to increase it back higher some limited level. That's some console output (after <Fn + Down> to min and <Fn + Up> to "max"): > $ cat /sys/devices/platform/samsung/backlight/samsung/actual_brightness > 2 > > $ cat /sys/devices/platform/samsung/backlight/samsung/brightness > 8 > > $ cat /sys/devices/platform/samsung/backlight/samsung/max_brightness > 8
The workaround is a using the rebuilt <samsung-laptop.ko> module (with the attached <samsung-laptop.ko> and <Makefile>).
Created attachment 76471 [details] The <samsing-laptop> source (from a too old kernel version) with added RV520 support
Created attachment 76491 [details] <Makefile> for building the module with attached <samsung-laptop.c>