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#1 2020-08-17 13:57:52

glitchdot
Member
Registered: 2019-11-07
Posts: 6

Lenovo Legion 5i backlight control problem

I have dual boot Win10 and Archlinux on Lenovo Legion 5i. Everything seems to work fine except screen brightness control. The brightness control and brightness hotkeys work fine on Windows 10, while Archlinux boots with the last brightness level set in Windows and without possibility to change.

The laptop has Nvidia RTX 2060, and I use optimus-manager hybrid mode with PCI-Express Runtime D3 (RTD3) Power Management.

The screen brightness doesn't change with xfce4-power-manager or xorg-xbacklight. I tried everything listed in https://wiki.archlinux.org/index.php/Backlight and in https://wiki.ubuntu.com/Kernel/Debugging/Backlight, and nothing seems to work. Only slight difference is noticeable if I add acpi_backlight=vendor, but again the screen brightness cant change.

With default kernel parameters:

$ ls /sys/class/backlight/
intel_backlight  

with acpi_backlight=vendor

$ ls /sys/class/backlight/
ideapad
intel_backlight  

Following the advice from the wiki I tried echo 5 > /sys/class/backlight/intel_backlight/brightness and echo 5 > /sys/class/backlight/ideapad/brightness, but neither change the brightness.

Only way to change the brightness right now is "xrandr --output eDP-1 --brightness 0.3", however in this way the brightness goes down for few second and then goes back to previous state automatically.

Additional system information

System:    Host: glitchdot Kernel: 5.8.1-arch1-1 x86_64 bits: 64 Desktop: i3 4.18.2 Distro: Arch Linux 
Machine:   Type: Laptop System: LENOVO product: 81Y6 v: Lenovo Legion 5 15IMH05H 
           serial: <superuser/root required> 
           Mobo: LENOVO model: LNVNB161216 v: SDK0R32862 WIN serial: <superuser/root required> 
           UEFI: LENOVO v: EFCN32WW date: 05/11/2020 
Battery:   ID-1: BAT0 charge: 52.8 Wh condition: 62.9/60.0 Wh (105%) 
CPU:       Topology: 6-Core model: Intel Core i7-10750H bits: 64 type: MT MCP L2 cache: 12.0 MiB 
           Speed: 800 MHz min/max: 800/5000 MHz Core speeds (MHz): 1: 800 2: 800 3: 800 4: 800 5: 800 
           6: 800 7: 800 8: 800 9: 800 10: 800 11: 801 12: 800 
Graphics:  Device-1: Intel driver: i915 v: kernel 
           Device-2: NVIDIA driver: nvidia v: 450.57 
           Device-3: IMC Networks Integrated Camera type: USB driver: uvcvideo 
           Display: x11 server: X.Org 1.20.8 driver: modesetting,nvidia resolution: 1920x1080~144Hz 
           OpenGL: renderer: Mesa Intel UHD Graphics (CML GT2) v: 4.6 Mesa 20.1.5 
Audio:     Device-1: Intel driver: snd_hda_intel 
           Sound Server: ALSA v: k5.8.1-arch1-1 
Network:   Device-1: Intel driver: iwlwifi 
           IF: wlp0s20f3 state: up mac: 8c:c6:81:f5:a5:7d 
           Device-2: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet driver: r8169 
           IF: enp7s0 state: down mac: 00:2b:67:9b:36:07 
Drives:    Local Storage: total: 1.38 TiB used: 56.00 GiB (4.0%) 
           ID-1: /dev/nvme0n1 vendor: SK Hynix model: HFM512GDHTNI-87A0B size: 476.94 GiB 
           ID-2: /dev/sda vendor: Seagate model: ST1000LM035-1RK172 size: 931.51 GiB 
           ID-3: /dev/sdb type: USB model: General size: 7.50 GiB 
Partition: ID-1: / size: 22.79 GiB used: 7.61 GiB (33.4%) fs: ext4 dev: /dev/nvme0n1p5 
           ID-2: /home size: 203.89 GiB used: 48.39 GiB (23.7%) fs: ext4 dev: /dev/nvme0n1p6 
Swap:      ID-1: swap-1 type: partition size: 3.91 GiB used: 0 KiB (0.0%) dev: /dev/sda3 
Sensors:   System Temperatures: cpu: 46.0 C mobo: N/A 
           Fan Speeds (RPM): N/A 
Info:      Processes: 260 Uptime: 28m Memory: 15.50 GiB used: 1.24 GiB (8.0%) Shell: Zsh inxi: 3.1.0

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#2 2020-09-28 21:21:43

bnounu
Member
Registered: 2020-09-28
Posts: 3

Re: Lenovo Legion 5i backlight control problem

I'm having a similar issue on on a Lenovo Legion 7 15IMHg0 (same generation as the Legion 5i).

echo 1 > /sys/class/backlight/intel_backlight/bl_power
echo 0 > /sys/class/backlight/intel_backlight/brightness

These two commands turn off the display, but setting the brightness to any positive value lights up the display to full brightness.

I tried fiddling with the i915 module options, kernel acpi_osi and acpi_backlight options, different X11 configs, and nothing works. The only way to make backlight adjustable (besides xrandr) is going to the BIOS and enabling discrete graphics and writing to /sys/class/backlight/nvidia_0/brightness. This disables the integrated GPU and wires the display to the NVidia GPU. Of course, I don't want to use the dedicated GPU all the time, but at least this indicates that the GPU driver is capable of controlling the back light and that no other driver is needed.

The display panel is a BOE08EA (BOE NV156FHM-NY5). Other system info:

System:    Host: arch Kernel: 5.8.12-xanmod1-1 x86_64 bits: 64 compiler: N/A Desktop: Xfce 4.14.2 Distro: Arch Linux
Machine:   Type: Laptop System: LENOVO product: 81YU v: Lenovo Legion 7 15IMHg05 serial: <superuser/root required>
           Mobo: LENOVO model: LNVNB161216 v: No DPK serial: <superuser/root required> UEFI: LENOVO v: E9CN58WW(V4.03)
           date: 09/15/2020
Battery:   ID-1: BAT1 charge: 82.6 Wh condition: 82.6/80.0 Wh (103%)
           model: 0x43 0x65 0x6C 0x78 0x70 0x65 0x 0x4C 0x31 0x39 0x43 0x34 0x50 0x8000 status: Full
CPU:       Info: 8-Core model: Intel Core i7-10875H bits: 64 type: MT MCP arch: N/A L2 cache: 16.0 MiB
           flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 73598
           Speed: 4897 MHz min/max: 800/5100 MHz Core speeds (MHz): 1: 4901 2: 4903 3: 4897 4: 4886 5: 4916 6: 4914 7: 4890
           8: 4900 9: 4907 10: 4932 11: 4911 12: 4893 13: 4884 14: 4903 15: 4936 16: 4902
Graphics:  Device-1: Intel UHD Graphics vendor: Lenovo driver: i915 v: kernel bus ID: 00:02.0
           Device-2: NVIDIA TU106BM [GeForce RTX 2060 Mobile] vendor: Lenovo driver: nvidia v: 455.23.04 bus ID: 01:00.0
           Device-3: Syntek Integrated Camera type: USB driver: uvcvideo bus ID: 1-6:4
           Display: x11 server: X.Org 1.20.9 driver: modesetting,nvidia resolution: 1: 2560x1440~60Hz 2: 1920x1080~144Hz
           OpenGL: renderer: GeForce RTX 2060/PCIe/SSE2 v: 4.6.0 NVIDIA 455.23.04 direct render: Yes
Audio:     Device-1: Intel Comet Lake PCH cAVS vendor: Lenovo driver: snd_hda_intel v: kernel bus ID: 00:1f.3
           Device-2: NVIDIA TU106 High Definition Audio vendor: Lenovo driver: snd_hda_intel v: kernel bus ID: 01:00.1
           Sound Server: ALSA v: k5.8.12-xanmod1-1

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#3 2020-09-29 21:25:11

euromatlox
Member
Registered: 2017-02-10
Posts: 110

Re: Lenovo Legion 5i backlight control problem

In my Lenovo T440s backlight brightness works perfectly.

/etc/udev/rules.d/97-backlight.rules

ACTION=="add", SUBSYSTEM=="backlight", KERNEL=="intel_backlight", RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness"
ACTION=="add", SUBSYSTEM=="backlight", KERNEL=="intel_backlight", RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"

Reboot, then use following commands (example). System remembers setting. Confirm that by rebooting again.

To set: echo 180 > /sys/class/backlight/intel_backlight/brightness
To check current value: cat /sys/class/backlight/intel_backlight/brightness

Last edited by euromatlox (2020-09-29 21:29:24)

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#4 2020-09-29 22:52:23

2ManyDogs
Forum Fellow
Registered: 2012-01-15
Posts: 4,645

Re: Lenovo Legion 5i backlight control problem

As the OP has not been back since the original post, I am going to consider this topic abandoned and close it.

glitchdot, if you come back and want this topic reopened, please use the Report link.

bnounu, if you still need help, please open your own topic. That way you will be able to mark it [SOLVED] when you find a solution.

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