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4 Posts

08-19-2010

GB

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X1 Extreme: Backlight brightness not working with Linux in Hybrid mode (Intel)

2019-11-06, 18:02 PM

I'm trying to lower the brighness when 'Intel (power saving)' mode is enabled.

 

Not worried about key bindings for the moment - I'll cross that bridge when I come to it.

 

The biggest problem is that direct changes to the driver interface doens't seem to be having an effect:

 

  /sys/class/backlight/intel_backlight/brightness

 

I have tried variations of the following kernel command line parameters, to no avail:

 

  thinkpad-acpi.brightness_enable=1

  cpi_osi=linux

  acpi_brightness=vendor

 

If this situation is not resolved, I will have to return the laptop, which I'm at pains to do.

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3 Posts

11-05-2019

CH

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Re: X1 Extreme: Backlight brightness not working with Linux in Hybrid mode (Intel)

2019-11-06, 19:06 PM

Same Problem here. Not Brightness on Linux Hybrid Driver.

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87 Posts

12-17-2018

US

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Re: X1 Extreme: Backlight brightness not working with Linux in Hybrid mode (Intel)

2019-11-07, 12:20 PM

Do you have an OLED on non-OLED panel also what is you BIOS level this informwation would assist in solving your issue.

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4 Posts

08-19-2010

GB

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Re: X1 Extreme: Backlight brightness not working with Linux in Hybrid mode (Intel)

2019-11-07, 12:26 PM

I used the firmware updater tool to upgrade to the latest BIOS.

 

The screen is 15.6" UHD LED Backlight, OLED. 

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87 Posts

12-17-2018

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Re: X1 Extreme: Backlight brightness not working with Linux in Hybrid mode (Intel)

2019-11-07, 12:35 PM

The update for OLED brightness controls from Intel went into the 5.3 kernel, I know that Fedora 31 and Debian 10 testing stream are already using this kernel or higher other Distros may not have moved that far and you would need to manually update the kernel to get it properly working on those 

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4 Posts

08-19-2010

GB

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Re: X1 Extreme: Backlight brightness not working with Linux in Hybrid mode (Intel)

2019-11-07, 13:02 PM

I'm on 5.3.0-19.

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87 Posts

12-17-2018

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Re: X1 Extreme: Backlight brightness not working with Linux in Hybrid mode (Intel)

2019-11-07, 13:35 PM

I rechecked my notes and it is not the 5.3 but it was put in in 5.4 rc4  here is the patch  

https://patchwork.freedesktop.org/patch/334989/?series=67595&rev=2 

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3 Posts

12-07-2019

US

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Re: X1 Extreme: Backlight brightness not working with Linux in Hybrid mode (Intel)

2019-12-07, 2:12 AM

I tried a few kernels (Fedora 31) but no luck here (P1 Gen2 - 4K AMOLED UHD touchscreen).

~~~
$ rpm -qa | grep kernel-5 | tail -n2
kernel-5.4.2-350.vanilla.knurd.1.fc31.x86_64
kernel-5.5.0-0.rc0.git6.1.vanilla.knurd.1.fc31.x86_64
~~~

I'm not sure which panel the P1 Gen2 has- is there any difference in the panel? The patch seems to be for the X1 Yoga.

For anyone else that stumbles upon this, I ended up using this - it works, but not ideal as redshift and night light mess it up.

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3 Posts

12-07-2019

US

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Re: X1 Extreme: Backlight brightness not working with Linux in Hybrid mode (Intel)

2019-12-07, 4:15 AM
A quick follow-up, setting kernel parameter 'i915.enable_dpcd_backlight=1' seems to do *something* but it's really weird, almost like it cycles brighter -> lower -> brighter

But now, I can do this and it seems to change the brigtness:

~~~
[root@localhost intel_backlight]# pwd
/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight

[root@localhost intel_backlight]# echo 20000 > brightness

[root@localhost intel_backlight]# echo 40000 > brightness

[root@localhost intel_backlight]# echo 50000 > brightness

[root@localhost intel_backlight]# echo 60000 > brightness

[root@localhost intel_backlight]# echo 10000 > brightness

[root@localhost intel_backlight]# echo 5000 > brightness
~~~

But these values do not work properly, I can change them randomly and the brightness will go up and down, without a proper pattern to the values.

e.g. I could echo 2000 and then 16000 and then 3000 and it would go brighter -> less bright -> less bright

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3 Posts

12-05-2019

FR

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  • Message 10 of 13

Re: X1 Extreme: Backlight brightness not working with Linux in Hybrid mode (Intel)

2019-12-07, 17:08 PM

It seems a patch exist https://gitlab.freedesktop.org/drm/intel/issues/510 but I have no time yet to patch and compile kernel. regarding to comments, you don't have to manually set enable_dpcd_backlight, it should work out the box

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