https://bugs.kde.org/show_bug.cgi?id=381199
Bug ID: 381199 Summary: Broken brightness control with kernel module (ex. nvidia-bl) Product: Powerdevil Version: 5.10.0 Platform: Other OS: Linux Status: UNCONFIRMED Severity: normal Priority: NOR Component: general Assignee: plasma-de...@kde.org Reporter: vsnrain....@gmail.com Target Milestone: --- Overview: Since 5.10, it is no longer possible to adjust brightness on my system, which requires special kernel module for brightness to work. I tried to look at what caused this, and found that in following commit https://cgit.kde.org/powerdevil.git/commit/?id=86c3548d103ff5966366788220796de629be9230 Was attempt to add feature that powerdevil will control only brightness of active device. Part of relevant code is following: /daemon/backends/upower/backlighthelper.cpp bool BacklightHelper::isRawBacklightEnabled(const QString &interface) { QFile file(BACKLIGHT_SYSFS_PATH + interface + "/device/enabled"); if (!file.open(QIODevice::ReadOnly | QIODevice::Text)) { return false; } QByteArray buffer = file.readLine().trimmed(); if (buffer == "enabled") { return true; } return false; } As you can see, it was implemented by skipping all brightness devices which in BACKLIGHT_SYSFS_PATH + interface + "/device/enabled" does not return "enabled". The problem is, there is no property "device/enabled" in my nvidia_backlight device: ls -la /sys/class/backlight/nvidia_backlight/ total 0 drwxr-xr-x 3 root root 0 Jun 2 22:50 . drwxr-xr-x 3 root root 0 Jun 2 22:50 .. -r--r--r-- 1 root root 4096 Jun 2 23:02 actual_brightness -rw-r--r-- 1 root root 4096 Jun 2 23:02 bl_power -rw-r--r-- 1 root root 4096 Jun 2 22:54 brightness -r--r--r-- 1 root root 4096 Jun 2 22:50 max_brightness drwxr-xr-x 2 root root 0 Jun 2 23:02 power lrwxrwxrwx 1 root root 0 Jun 2 22:50 subsystem -> ../../../../class/backlight -r--r--r-- 1 root root 4096 Jun 2 22:50 type -rw-r--r-- 1 root root 4096 Jun 2 22:50 uevent so powerdevil tries to open this file, fails, and always skips this brightness device. I recompiled powerdevil with "return true" in mentioned function, and brightness control works again, so it seems that problem in indeed in this part. Steps to Reproduce: use kernel module for brightness device, tested on Nvidia GF 9400M with nvidia-bl kernel module. Actual Results: powerdevil always skips brightness device, because it cannot open file /sys/class/backlight/nvidia_backlight/device/enabled, which does not exist. Expected Results: register and control brightness device. -- You are receiving this mail because: You are watching all bug changes.