How can i set the screen brightness?

Help
#1

how can i set the brightness of my screen? i’ve checked the screen preferences but all i can see are settings for resolution and such.

#2

Screen preference include brightness slider. If it is not visible it means that current video driver do not support setting brightness.

What is your video adapter?

#3

i’m just using intel integrated graphics (i assume that’s what you’re asking)

#4

@PulkoMandy is developing intel video drivers.

#5

so for the time being i’m screwed, right?

#6

Likely so. Lets wait response from video driver developer. Before this please run listdev and listimage kernel in Terminal and paste it here. Also does brightness control work in other OS?

#7

listdev: https://gist.github.com/benclarkk/db8f72cfe2ea533460b3e84b58dafce4
not listdev: https://gist.github.com/benclarkk/ed3941b136417b62ec38f83d481a0452
and yeah, it does

#8

1332 0xffffffff824e7000 0xffffffff824eb000 0 0 /boot/system/add-ons/kernel/drivers/dev/graphics/vesa

VESA fallback driver is used. Your video adapter seems not supported yet.

Screen brightness
#9

Hi,
I made some changes to support brightness control in the VESA driver, but it seems no VESA BIOS actually implements the required calls. So there is nothing to be done from the video driver side. I think however that it’s possible to set the brightness from ACPI in that case. However I have no idea how that works.

#10

When changing the actual brightness of the display isn’t possible, could Haiku fake changing the brightness by having a transparent black overlay that fills the screen, and decreasing the brightness slider would increase the opacity of the overlay? The effect reduces the overall intensity of the display without lowering the backlight brightness. I saw this feature in NomadBSD, and this is just a guess at how it works.

#11

Actually ACPI display brightness isn’t that hard, and most of the hard ACPI driver work is already done: https://github.com/haiku/haiku/tree/master/src/add-ons/kernel/drivers/display
TODO’s here: https://github.com/haiku/haiku/blob/master/src/add-ons/kernel/drivers/display/display.cpp#L15

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#12

My tablet have this ACPI methods, so brightness control should work when implemented.

#13

I was going to comment about the desirability of laptop display brightness adjustment but see this is already under discussion. Linux (Mint 20.3 in my case) has a power management applet that regulates screen brightness.) Any progress in this area?

#14

Setting screen brightness works for drivers that support it - I think it’s only intel_extreme atm(?)

There’s a slider in the Screen preferences and you can also set it from the command line with the screenmode command.

#15

Here is a (known broken) review for radeon backlights, I don’t have any hardware to test this on, but perhaps another interested party could pick it up. https://review.haiku-os.org/c/haiku/+/2786

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#16

Only intel_extreme and only a limited selection of devices (depending on the video card generation, and the way the display is wired to it).

Instead of controlling the hardware directly like this, it should be possible to write a driver using ACPI, which would work on a lot more hardware.

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