Why does setterm turn off backlight only some laptops?

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Why does setterm turn off backlight only some laptops?

Postby Danathar » 2021-01-25 15:34

On Debian Buster....

I have two laptops in console mode running with a VESA.

With the first when using setterm and it reaches the time that I've set to blank the screen (setterm -blank 5) turns off the screen using APM completely (backlight and all).

Another laptop with same command it blanks the screen but does not turn off the backlight. Even using --powerdown does not work, yet using "vbetool dpms off" WILL turn the whole screen off INCLUDING backlight. Is there a bug in setterm or is there an APM setting somewhere that needs to be changed on the first laptop to get it to turn the backlight off with setterm?

thoughts?

and as always...THANKS! :)
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Re: Why does setterm turn off backlight only some laptops?

Postby Head_on_a_Stick » 2021-01-26 15:36

Perhaps a terminfo bug? That's just a guess though.
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Re: Why does setterm turn off backlight only some laptops?

Postby Danathar » 2021-01-27 11:57

Head_on_a_Stick wrote:Perhaps a terminfo bug? That's just a guess though.


Thanks for the response. I was contemplating submitting a bug, but I don't want to do it if it's not a bug. I managed to find a post on another forum that says if you disable acpi in the kernel on bootup and just use APM only...given that most kernels are compiled with both (have not checked the debian Kernel) that seems to fix the problem with setterm not turning off the backlight. I've not tested it, but will soon.
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