Doesn't detect external monitors about brightnessctl HOT 7 CLOSED

The right thing to do is just to support multiple devices in /sys/class/backlight. A user can then install ddcci-driver-linux (currently an out-of-tree module), which through the ddcci-backlight module provides backlight interfaces for external displays that work exactly like intel_backlight.

WIth multiple device support, there's nothing for brightnessctl to do. It's not a good idea to implement the user-space approach for external display management, as it's slow, complicated, and a major hack. Just hope for ddcci-driver-linux to be upstreamed.

from brightnessctl.

I've just read deeper that the tool does not manage external monitor brightness by design. So this issue is not a bug, rather may be treated as an feature request.

from brightnessctl.

You can use ddcutil for that. I will keep this open for now.

from brightnessctl.

It works already

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@kennylevinsen
I just would like to understand a little bit more about why you said "WIth multiple device support, there's nothing for brightnessctl to do".

Until I read your sentence I thought it would be quite reasonable to use the same program (in this case brightnessctl) to control the brightness of multiple monitors. But now I'm wondering if I'm missing something.

I read that you also said that "The right thing to do is just to support multiple devices in /sys/class/backlight.". Is that the case of xrandr, for example? Even if it is, it seems the backlight thing seems to be transparent to the user - we just run xrandr ... --brightness ... and that's it.

Could you clarify, please?

Thank you.

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there's nothing for brightnessctl to do implies that if the system has ddci-driver-linux installed, the monitors will be exposed in /sys/class/backlight, and thus brightnessctl will be able to deal with them without any changes.

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I might not be against a PR which would add direct DDCI (or w/e it's called) support.

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