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Tasklist

FS#42618 - [linux] Doesn't turn off display when backlight level is set to zero on 3.17-1 kernel.

Attached to Project: Arch Linux
Opened by Yarosh Yuriy (void.nugget) - Thursday, 30 October 2014, 11:16 GMT
Last edited by Doug Newgard (Scimmia) - Sunday, 15 October 2017, 14:22 GMT
Task Type Bug Report
Category Kernel
Status Closed
Assigned To Tobias Powalowski (tpowa)
Architecture x86_64
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No

Details

Description:

I've got Dell Inspiron 7720 SE laptop with Core i7-3610QM and Intel HD Graphics 4000.
So after updating kernel to 3.17.1-1 my backlight doesn't turn off when I do `xbacklight -dec 100`, but it's works in any other available ranges.
I've managed to turn it off via setting PWM frequency manually with `intel_reg_write 0xC8254 0x00` from `intel-gpu-tools` package.
`xset dpms force off` is turning it off, but after some mouse movement or keypressing it turns back on.
Register value is taken blindly from backlight Archwiki article. I'm glad that HD4000 uses the same register as i915 and my panel haven't smoked up.

I don't think that it's some kind of vendor bug, 'cuz it's started after recent kernel update.

Kernel params: quiet splash acpi_backlight=vendor video.use_native_backlight=1 rcutree.rcu_idle_gp_delay=1

Steps to reproduce:
Update to 3.17.1-1 kernel on HD4000 graphics
Watch as backlight doesn't turns off with `xbacklight`
This task depends upon

Closed by  Doug Newgard (Scimmia)
Sunday, 15 October 2017, 14:22 GMT
Reason for closing:  No response
Comment by Samantha McVey (samcv) - Friday, 10 June 2016, 01:17 GMT
You are saying that the functionality changed from being able to have the backlight turn off completely based on xbacklight -dec 100 to suddenly it not working? This may be an issue with which method of setting the brightness you are using. Are you able to turn off backlight of the display by using:
$ sudo su
$ echo 0 > /sys/class/backlight/intel_backlight/brightness
Please reply whether this works.
Comment by mattia (nTia89) - Sunday, 01 October 2017, 15:41 GMT
is this issue still valid?

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