Well I figured out that this issue is present in any laptop I was able to test, I tried with several laptops with new and not so new hardware and it is always the same. Asus, MSI, Lenovo, HP and Compaq, Dell, Toshiba, Intel Classmate Netbooks have the same problem after kernel 3.17. Is there anything else that I could try?
Thnx -- 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 any kernel above 3.17 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 : firstname.lastname@example.org Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp