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.
Can you find which kernel this first occurred in? Ubuntu mainline kernel PPA's are available at http://