[SOLVED] HP 8440p Brightness Control in Petra

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Robynsveil
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[SOLVED] HP 8440p Brightness Control in Petra

Post by Robynsveil »

Does anyone have any experience with the HP 8440p laptop, and/or have issues with Brightness Control in Mint-Petra?

I've purchased a HP 8440p (i5, 4 gig RAM, Intel graphics) laptop which had Windows 7 Professional running on it. The brightness control worked fine in Windows, and the screen defaulted to completely bright. I deleted Windows 7, and replaced with Petra 64-bit Cinnamon. Everything appears to work fine except for the brightness control, which seems stuck at half-brightness.

I have tried a number of suggestions offered on a number of forums.
First, the GRUB solution... tried these each on its own:

Code: Select all

- acpi_osi=
- acpi_backlight=vendor
- acpi_osi=Linux acpi_backlight=vendor 
and finally:

Code: Select all

 acpi_osi=\"!Windows 2012\" 
All to no avail.

Tried this command:

Code: Select all

for i in /sys/class/backlight/*; do echo -e "\n $i"; cat $i/{brightness,max_brightness,actual_brightness}; done
which returned:
*****************************
/sys/class/backlight/acpi_video0
24
24
24

/sys/class/backlight/intel_backlight
464
648
464
************************************************
Not exactly sure how to proceed from here...
Last edited by LockBot on Wed Dec 28, 2022 7:16 am, edited 2 times in total.
Reason: Topic automatically closed 6 months after creation. New replies are no longer allowed.
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roblm
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Re: HP 8440p Brightness Control in Petra

Post by roblm »

The link below has information about other users having problems with brightness control with the
HP 8440p laptop but the posts are older and mostly from Ubuntu users:

http://www.linlap.com/hp_elitebook_8440p

Do you need the ability to adjust the brightness to different levels or can it be set to one level?

Try typing this command in the Terminal to see if your system can control the brightness level:
sudo echo 648 > /sys/class/backlight/intel_backlight/brightness

If that doesn't work then type:
echo 648 | sudo tee /sys/class/backlight/intel_backlight/brightness
Robynsveil
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Re: HP 8440p Brightness Control in Petra

Post by Robynsveil »

Thank you for your reply, Roblm. I had googled before and found that page (sorry I failed to mention that).

I've just re-installed Petra on this system (too much experimentation with different settings and I have no idea where I am now, so starting fresh) and will try your suggestion before I do anything else.

Just a note on the default behaviour of the [fn][F9] and [fn][F10] key combinations in Petra - this is before I do anything to the settings:
- an onscreen display appears with either keystroke combination
- pressing [fn][F10] once shows the "thermometer bar" at max setting
- pressing [fn][F9] about 5 or 6 times shows that "thermometer bar" setting decreasing and the screen brightness diminishing up to a point, then although the "thermometer bar" continues to decrease, the screen does not dim any further
- pressing [fn][F10] repeatedly now shows the "thermometer bar" returning to max setting... just before it reaches max setting, the screen flashes bright for a split second, then dims again to its default level

I will now try the code in terminal you've suggested and report back with my results. Thank you again! :)

(PS: need to turn on notifications, I think - didn't get this for a few days!)
Robynsveil
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Re: HP 8440p Brightness Control in Petra

Post by Robynsveil »

Oh, forgot to answer your question! I'm happy for the brightness to stay at full-brightness if given that as the only other option. It would be nice to be able to vary it, of course.

So, I did as you suggested. On my system, Terminal required me to be super user (threw a 'permission denied' when I tried to do it with 'sudo') to run these commands, which I became with 'sudo su'.

On the first command, the screen went completely black immediately and stayed that way until I pressed the [fn][F10] key set. Then, the screen went from dim back to partly-bright, with that brief flash I'd described in the previous post.
I had to remove the word 'sudo' from the second command, which I then invoked with exactly the same results.
Robynsveil
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Re: HP 8440p Brightness Control in Petra

Post by Robynsveil »

I had save my .bash_history file from the previous install, so I had a look at what I'd done before, and ran this:

Code: Select all

for i in /sys/class/backlight/*; do echo $i; cat $i/brightness; done
which returned:
/sys/class/backlight/acpi_video0
23
/sys/class/backlight/intel_backlight
430
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roblm
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Re: HP 8440p Brightness Control in Petra

Post by roblm »

Robynsveil,

Did you try using this command without removing the sudo? You don't need to type "sudo su" first. It should work to give
maximum brightness: echo 648 | sudo tee /sys/class/backlight/intel_backlight/brightness

I would suggest installing xbacklight from the synaptic package manager. Then open the Terminal and type: xbacklight -set 100

The value can be from 5 to 100. If the setting is not right then decrease the value by 5 or 10 at a time. If this works then create a
startup program. Go to Menu → Preferences → Startup Applications. Click on "Add". In the new window, under "Name" you can put
anything you want. In the "Command" window put: xbacklight -set X
where X is the value you got from testing.

If it doesn't work, then try each kernel parameter again and see if xbacklight now works.

You can try testing the kernel parameters in the GRUB file. The effect will only last for one session. At the GRUB boot menu select
the correct line but don’t press Enter. Press the “E” key to edit. If no menu shows then hold down the shift key while starting. Using
the arrow keys, go down to the line that starts with: linux /boot/vmlinuz.......................ro quiet splash $vt_handoff

Add a space to the end of the line and then add the first parameter below:
acpi_osi=Linux
acpi_backlight=vendor
acpi_osi=Linux acpi_backlight=vendor
acpi_osi='!Windows 2012'
acpi_osi=

Press Ctrl+X to start your system. Repeat the steps with all the parameters if necessary. If one of the parameters allows xbacklight
to work, then make the change persistent. In the Terminal run this command: gksudo gedit /etc/default/grub

Change the line: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
by adding a space after the word “splash” and then add the parameter that worked.
Save the file and then type this command in the Terminal: sudo update-grub
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Re: HP 8440p Brightness Control in Petra

Post by Robynsveil »

Thanks, Rob, for all that detail work. Sorry I couldn't get back to you - we were in the process of moving after 13 years in the same place (amazing what accumulates!), so I'm typing here from the new place - but I just wanted to say that I did follow your instructions to the letter, with end result that the [fn]-[F9]/[fn]-[F10] behaviour is still the same as I spelled out above but the screen seems a bit brighter now. I did end up with this setting in GRUB:

acpi_osi=\"!Windows 2012\"

The others didn't do anything but make things dimmer, ultimately.

I did read on another site that there was some sort of auto-brightness adjustment feature built into these units which may have not been addressed by the Linux driver-writers... who knows.

Thanks again for taking the time to offer suggestions. The unit works as-is, even though the brightness isn't quite on a par with my other system. All good! :)
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roblm
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Re: HP 8440p Brightness Control in Petra

Post by roblm »

I'm still puzzled why this command doesn't work just as it is to set maximum brightness:
echo 648 | sudo tee /sys/class/backlight/intel_backlight/brightness

with 648 being the value for max_brightness you got from the command in your first post.

You could try temporarily changing the permissions of the brightness file with this command in the Terminal:
sudo chmod a+rw /sys/class/backlight/intel_backlight/brightness
and then type: echo 648 > /sys/class/backlight/intel_backlight/brightness

You can try using xrandr and xgamma to increase the screen brightness, but only a little more because using them will
negatively affect the screen colors. First open the Terminal and type: xrandr

It will list the video outputs available on your system such as LVDS-1 and DVI-I-1. Get the name of the one that says it
is “connected”. Then type this command, replacing X with the connected output name: xrandr --output X --brightness 1.1

For example, for my computer the command would be: xrandr --output DVI-I-1 --brightness 1.1
You can also try 1.2 for the value. Change the value to 1.0 to reverse the changes.

Then try using xgamma by typing: xgamma -gamma 1.1
Then try the value of 1.2
Compare the screen colors using xrandr and xgamma.

Another command to try is this:
pkexec /usr/lib/gnome-settings-daemon/gsd-backlight-helper --set-brightness 648

The last option is to install a newer mainline kernel from here:
http://kernel.ubuntu.com/~kernel-ppa/mainline/
Robynsveil
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Re: HP 8440p Brightness Control in Petra

Post by Robynsveil »

Sorry to get back to you so late, Robim. Not sure how to get email notifications actually happening: I did enable it in my settings, but still find myself days late and dollars short on this.
On the brightness thing: discovered something about this particular machine. It has this sensor that, if a shadow passes between the sensor and the light source, the screen dims. As in: it's not a bug, it's a feature. :? So, I just make sure plenty of light is falling on the screen and the brightness is right up there where it's meant to be. :| Go figure.
The way I figured it out was: at work, with lots of fluorescent lights around, the screen was bright as anything. At how, with only an energy-saving dome light under the fan, the screen was noticeably darker.

So, I'll mark this thread as solved... and thank you for all your hard work on this. Your input was very detailed and excellent to follow, which I did, to the letter. :)
Monsta
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Re: [SOLVED] HP 8440p Brightness Control in Petra

Post by Monsta »

A lot of time has passed - now you might want to read this thread.
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