09-16-2019 05:18 PM
I got my Legion Y740 working on Arch Linux, the only issue is the brightness control. The function keys changes the values of /sys/class/backlight/intel_backlight and /sys/class/backlight/ideapad.
I'm currently using the kernel boot parameters acpi_backlight=vendor. I tried several combinations from https://wiki.ubuntu.com/Kernel/Debugging/Backlight but none worked.
The only workarround is using "xrandr --output eDP-1 --brightness 0.5" but that does not work under wayland (Gnome), only on X.
The GPU is Nvidia RTX 2070, but it's off using bumblebee.
Anyone got the brightness control working on this or a similar model?
Thanks in advance
09-29-2019 04:26 AM
Just want to share this with other people who like me search for this issue with no luck.
I had same issue with Y740 RTX 2060 BIOS v1.06.
After hundreds of searches and dozens trials the only way I found to fix this, is to set BIOS setting to use descrete graphics only.
With this option brightness works out of the box.
You probably will have other issues thou like:
video crash on clean linux install (so need to install with intel card and switch BIOS after propritary nvidia drivers install),
xorg crash on login with Gnome (switch to KDE or make X11 run as root),
wrong DPI in KDE (simple fix in xorg config).
So I think currently with Y740 we have only two options:
1. use switchable graphics intel/nvidia with full backlight and xrandr brightness hack
2. use nvidia only.
And wait kernel/drivers update to make it work in any case.
10-09-2019 01:03 AM - edited 10-09-2019 01:08 AM
Thanks for the feedback! I am currently using Y740 and I encountered the similar issue. I have been finding similar solution for a few days. Regarding your comment, may I ask for a bit clarity? (It may help with my own case)
1. you mention setting "discrete graphics" in BIOS can enable brightness adjustment, but introduces other issues, such as video crash on clean linux install. Can you elaborate more on the video crash issue and how to settle that? I think I encountered similar issue by the time I tried to install nvidia driver in my Ubuntu 16.04
2. you also mention other issue about xorg, such as xorg crash on login with Gnome. Can you also elaborate more on that?
And about waiting for the kernel / driver update, do you mean we have to wait for a Ubuntu kernel update / nvidia driver update to make it compatable with my Y740?
I would like to further elaborate my intention: ultimately I want to make a dual boot on my Y740 (Ubuntu 16.04 + Windows 10). I managed to install Ubuntu 16.04 on fresh but failed to install proprietary nvidia driver in many attempts (attempt including blacklist nouveau, changing BIOS configuration, installing nvidia driver in different way, changing the conf of grub ... etc). So I am looking for a solution to installing a proprietary nvidia driver in my Y740. If any Y740 user encountered similar issue and have settled it. I really look forward to your work-around!
10-09-2019 03:41 AM - edited 10-09-2019 04:31 AM
1. On install linux uses nouveau driver and it crashes. So need to use swichable graphics on ubuntu install and after installation of proprietary drivers you can set discrete only in BIOS.
2. When you login gnome crashes and goes back to login again. I fixed that with needs_root_rights = yes in /etc/X11/Xwrapper.config
But then later I moved to kubuntu which has no such issue with KDE.
I'm currently on kubuntu 19.04 with latest nvidia 435 drivers and all works well.
I had one more issue with crash on wakeup after suspend.
I fixed it downgrading kernel from 5.0.0-29 to 5.0.0-13. That also fixed wrong DPI issue. And now it seems everything works.
In coming days ubintu 19.10 should be relesed so I'm looking forward to test if kernel 5.3 will fix switchable graphics issue.
10-09-2019 11:32 AM - edited 10-09-2019 11:33 AM
All of the problems u encountered exactly matches with mine!
Kniwing that u installed latest version of ubuntu, do u think i can fix the above issues with ubuntu 16.04 installation?
10-09-2019 12:01 PM
Honestly I dont know. I'm new to this.
I think these problems related to recent hardware like latest Intel CPU, Nvidia 2060 and maybe display.
At least I found posts with same brightness problems with Dell XPS with 2060 card.
10-09-2019 10:50 PM
It's alright. I believe your experience will definitely help with my situation. Just want to dive deep a little bit:
1. Do you set "Switchable Graphics" by the time you freshly install Ubunutu? My Ubuntu installation is fine with "Discrete Graphics", but when it is set to "Switchable Graphics", annoying screen flickering happens, even in reinstallation
2. How you install your proprietary NVIDIA driver? Do you execute .run file or install by PPA? I did this by PPA but everytime I installed the proprietary NVIDIA driver, I either get trapped in infinite login loop or stuck into black screen after reboot. I have to uninstall all the NVIDIA thing to recover the crash
(3. I also had a problem on wakeup crash after suspend, just realized it is related to the kernel I used)
4. Could your kubuntu connect to external screen via HDMI? I can't do any HDMI connection in my current Ubuntu 16.04
10-14-2019 02:29 AM - edited 10-14-2019 02:39 AM
A few updates:
I tried Ubuntu 18.04 + Plasma KDE desktop + Kernel version 5.0.13. This build settled a number of issues I encountered in my first Ubuntu installation. However, screen flickering issue persists though with less seriousness and frequency (It occurs in some boots).
I would say the build works like a charm if the screen flickering issue have been (completely) settled! Anyway, I will keep trying until it works.
Btw, I gota say KDE desktop does settle the crash after nvidia installation, and kernel 5.0.13 does help with smooth wake up after suspend!
10-15-2019 08:12 AM - edited 10-15-2019 08:12 AM
Screen flickering is gone by the time I booted the machine today! I shall (also) verify that the above build is a stable one for Y740!