Brightness not changing

naghmash · 03-15-2015, 02:06 PM

Hi everyone,

i installed the latest version of deepin on my hp elitebook 6930p. but now the problem i am facing is that i cannot change the brightness. when i press the fn +f9/f10 the dialog appears but no change in brightness. Also from control center, brightness is full but not max.

However when i restart the pc it has full brightness but when plug in or out the ac adapter, its again gos to low level.

Please Reply ASAP.

Head_on_a_Stick · 03-15-2015, 02:36 PM

Have you tired using the "acpi_backlight=vendor" kernel parameter?

Edit the file at /etc/default/grub (as root) and add the parameter between the quotation marks after "GRUB_CMDLINE_LINUX="

Code:

GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

Then run this command & reboot:

Code:

sudo update-grub

If this doesn't work, post the output of:

Code:

ls /sys/class/backlight

naghmash · 03-15-2015, 10:58 PM

Quote:

Originally Posted by Head_on_a_Stick

Have you tired using the "acpi_backlight=vendor" kernel parameter?

Edit the file at /etc/default/grub (as root) and add the parameter between the quotation marks after "GRUB_CMDLINE_LINUX="

Code:

GRUB_CMDLINE_LINUX="acpi_backlight=vendor"

Then run this command & reboot:

Code:

sudo update-grub

If this doesn't work, post the output of:

Code:

ls /sys/class/backlight

the output of "ls /sys/class/backlight"

Code:

radeon_bl0

Head_on_a_Stick · 03-16-2015, 03:14 AM

I take it from your response that your backlight control is still not working?

For future reference, the more information you supply the greater the chance of a useful response -- read the top link in my signature.

Does this work:

Code:

sudo tee /sys/class/backlight/radeon_bl0/brightness <<< 50

You may have to alter the number to get a useful level but that is the value I use on my AMD laptop in a dim(ish) environment.

cyio · 03-19-2015, 01:49 AM

This post may help,see floor #9

Deepin Forum • 为了笔记本能调节亮度，装了kde…… http://www.linuxdeepin.com/forum/6/27381?#p136153

naghmash · 04-18-2015, 02:11 PM

Quote:

Originally Posted by Head_on_a_Stick

I take it from your response that your backlight control is still not working?

For future reference, the more information you supply the greater the chance of a useful response -- read the top link in my signature.

Does this work:

Code:

sudo tee /sys/class/backlight/radeon_bl0/brightness <<< 50

You may have to alter the number to get a useful level but that is the value I use on my AMD laptop in a dim(ish) environment.

yes the brightness increased. but i can only change it by altering the number i.e. "50". Also when i plugged out The AC adapter, it resets to the lower value.