CrunchBang Linux

kenwong

#! CrunchBanger

From: Hong Kong

Registered: 2009-07-26

Posts: 154

Display brightness levels (on Thinkpad T60)

On this machine, I can adjust the brightness of the display by pressing the Fn and Home/End buttons on the keyboard.  After booting into Waldorf, only 3 levels of brightness are available.  However, before booting into the desktop, there are at least 5 levels.  There are even 7 levels in Windows XP (dual boot alongside #!).

Any idea to make finer adjustments possible?  Thanks in advance.

Neil

#! CrunchBanger

From: Paragould AR USA

Registered: 2010-05-01

Posts: 166

Re: Display brightness levels (on Thinkpad T60)

Try adding the kernel parameter in your grub boot line: acpi_backlight=vendor
and reboot.

kenwong

#! CrunchBanger

From: Hong Kong

Registered: 2009-07-26

Posts: 154

Re: Display brightness levels (on Thinkpad T60)

^ Thanks Neil.  Unfortunately it doesn't make any changes.

tao te

Member

From: Berlin

Registered: 2012-07-30

Posts: 43

Re: Display brightness levels (on Thinkpad T60)

Try:

echo "N" | sudo tee /sys/module/video/parameters/brightness_switch_enabled

... or:

echo "Y" | sudo tee /sys/module/video/parameters/brightness_switch_enabled

Then add the following to your autostart, with "N" or "Y", depending which enables the more levels.

echo "N" > /sys/module/video/parameters/brightness_switch_enabled

Last edited by tao te (2012-10-06 15:40:45)

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T420s - i5-2520M, 4+4 GB Ram, 64 GB mSATA SSD, #! Linux

kenwong

#! CrunchBanger

From: Hong Kong

Registered: 2009-07-26

Posts: 154

Re: Display brightness levels (on Thinkpad T60)

^ thanks tao te.

echo "Y" | sudo tee /sys/module/video/parameters/brightness_switch_enabled

gave me 4 levels, occasionally.  It behaves inconsistently.  In /sys/class/backlight/acpi_video0/max_brightness, the value is 7, which is the same as the brightness levels I have in Windows XP.

Neil

#! CrunchBanger

From: Paragould AR USA

Registered: 2010-05-01

Posts: 166

Re: Display brightness levels (on Thinkpad T60)

Sorry...but about the best I can do is guess, as I have Xubuntu installed on my Thinkpad, and I have seven steps of brightness adjustment.  Don't know just what the dif would be.

Maybe try Tpb, and see if that offers any solution: http://www.thinkwiki.org/wiki/Tpb

kenwong

#! CrunchBanger

From: Hong Kong

Registered: 2009-07-26

Posts: 154

Re: Display brightness levels (on Thinkpad T60)

I just tried Neil's suggestion again.

Try adding the kernel parameter in your grub boot line: acpi_backlight=vendor
and reboot.

It works now! Perhaps, I forgot to execute "sudo update-grub" before reboot last time.

It is still not very ideal.  I have only 5 levels (vs 7 levels in Win XP).  And the max brightness value is 7, as indicated in /sys/class/backlight/thinkpad_screen/max_brightness.

Also, the differences between these 5 levels are not equal.

Googling obtains some discussions about the strange behaviour of two steps instead of one made by each hit of the Fn+Home/End keys.  This is one of those reports:

http://askubuntu.com/questions/3834/len … one-lookin

Probably, these 5 brightness levels expressed in percentage term are:
0% --> 28.6% --> 57.2% --> 85.8 --> 100% [as 100/7 = 14.3]

Anyway, thanks Neil for your help.

el_koraco

#!/loony/bun

From: inside Ed

Registered: 2011-07-25

Posts: 4,654

Re: Display brightness levels (on Thinkpad T60)

You can install xbacklight and map that to your hotkeys to increase by five percent or so. I can't guide you through it, read the xbacklight man page, look for the wiki article on xev to find the keycodes and look for rc.xml tweaks on how to do it.

kenwong

#! CrunchBanger

From: Hong Kong

Registered: 2009-07-26

Posts: 154

Re: Display brightness levels (on Thinkpad T60)

Thanks el_koraco.  Will take a look at it.

kenwong

#! CrunchBanger

From: Hong Kong

Registered: 2009-07-26

Posts: 154

Re: Display brightness levels (on Thinkpad T60)

Got these from googling:

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=627336

https://bugzilla.xfce.org/show_bug.cgi?id=7541

shem

Member

From: Universe 6.62606957(29)×10−34

Registered: 2012-05-16

Posts: 21

Re: Display brightness levels (on Thinkpad T60)

Got these from googling:

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=627336

https://bugzilla.xfce.org/show_bug.cgi?id=7541

On my laptop Asus K93S, I get the 10 levels of brightness back (instead of 5) by using the temporary solution in comment 13 on the xfce bugzilla:

xfconf-query -c xfce4-power-manager -n -t bool -p /xfce4-power-manager/change-brightness-on-key-events -s false

(Edit: Added link + corrected)

Last edited by shem (2012-10-10 06:38:48)

tao te

Member

From: Berlin

Registered: 2012-07-30

Posts: 43

Re: Display brightness levels (on Thinkpad T60)

Great! Thanks shem.

To disable the buggy brightness OSD, use:

xfconf-query -c xfce4-power-manager -n -t bool -p /xfce4-power-manager/show-brightness-popup -s false

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T420s - i5-2520M, 4+4 GB Ram, 64 GB mSATA SSD, #! Linux

kenwong

#! CrunchBanger

From: Hong Kong

Registered: 2009-07-26

Posts: 154

Re: Display brightness levels (on Thinkpad T60)

Alternatively, install the package xfce4-settings and use the command xfce4-settings-editor.

After adding the change-brightness-on-key-events key and setting the value to false, I now have 7 steps.  However, the bar in the brightness on screen level pop-up is now blank always (i.e., indicates zero whatever the actual brightness level is).  I therefore disabled it.