apport information ** Attachment added: "ProcEnviron.txt" https://bugs.launchpad.net/bugs/1682331/+attachment/4861615/+files/ProcEnviron.txt
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1682331 Title: Cannot get lowest brightness with kernel 4.4.0-53-generic Status in Linux Mint: New Status in linux package in Ubuntu: Confirmed Status in Fedora: New Bug description: I have been using kernel 3.16 in my Dell Laptop for a long time with Linux Mint 17 and previous versions and the problem here had never happened until LM18. Very often I set the lowest possible brightness, for example at night, or while I am flying for many hours. Using values from 0 to 4882 I used to run this command: # ie: Set lowest possible backlight brightness echo 0 > /sys/class/backlight/intel_backlight/brightnes I have always used intel_backlight instead of dell_backlight because it gives much more steps. Well now with kernel 4.4.0-53-generic it actually decreases the brightness but at night it is still very high even at 0 compared to the brightness levels I used to get with the same command. In fact, using a value of 0 with older kernels, the backlight is turned off. Just for testing, I have booted my laptop with Debian Live kernel 3.16.0-4-amd64 and it works perfectly. Nevertheless I was able to reproduce the issue on newer ubuntu releases and Fedora 25.3.1. That is how I realized that the problem was the kernel. Does anyone know if with newer kernels > 3.19 this is a well-known and tolerated behavior? Maybe the kernel code for intel_backlight was modified and ended up with this problem... Some system information: System: Kernel: 4.4.0-53-generic x86_64 (64 bit gcc: 5.4.0) Desktop: Cinnamon 3.2.7 (Gtk 3.18.9-1ubuntu3.2) Distro: Linux Mint 18.1 Serena Machine: System: Dell product: Inspiron 5520 v: A14 Bios: Dell v: A14 date: 05/13/2013 CPU: Dual core Intel Core i5-3210M (-HT-MCP-) cache: 3072 KB Graphics: Card: Intel 3rd Gen Core processor Graphics Controller Display Server: X.org 1.18.4 driver: intel $ ls /sys/class/backlight/ dell_backlight intel_backlight Also I always use the acpi_backlight=vendor kernel parameter and I can confirm that by changing its value, the problem persists. Thanks for your time, Frk. P.S. I have also asked about this issue without luck here => https://goo.gl/TVzH7z --- ApportVersion: 2.20.1-0ubuntu2.5 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: betops 6791 F.... pulseaudio CurrentDesktop: X-Cinnamon DistroRelease: Linux 18.1 HibernationDevice: RESUME=UUID=923be72b-35a8-4997-b31a-e6072b9d4a29 InstallationDate: Installed on 2017-02-05 (66 days ago) InstallationMedia: Linux Mint 18.1 "Serena" - Release amd64 20161213 MachineType: Dell Inc. Inspiron 5520 Package: linux (not installed) ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-53-generic root=UUID=ef4672c3-b0ed-47f3-a6b6-28e4e1e22d44 ro acpi_backlight=vendor intel_pstate=enable acpi_osi= acpi_irq_balance ProcVersionSignature: Ubuntu 4.4.0-53.74-generic 4.4.30 RelatedPackageVersions: linux-restricted-modules-4.4.0-53-generic N/A linux-backports-modules-4.4.0-53-generic N/A linux-firmware 1.157.8 Tags: serena serena Uname: Linux 4.4.0-53-generic x86_64 UnreportableReason: The report belongs to a package that is not installed. UpgradeStatus: No upgrade log present (probably fresh install) UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo vboxusers wireshark _MarkForUpload: False dmi.bios.date: 05/13/2013 dmi.bios.vendor: Dell Inc. dmi.bios.version: A14 dmi.board.name: 04G65K dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 8 dmi.chassis.vendor: Dell Inc. dmi.chassis.version: A14 dmi.modalias: dmi:bvnDellInc.:bvrA14:bd05/13/2013:svnDellInc.:pnInspiron5520:pvrA14:rvnDellInc.:rn04G65K:rvrA00:cvnDellInc.:ct8:cvrA14: dmi.product.name: Inspiron 5520 dmi.product.version: A14 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/linuxmint/+bug/1682331/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
