Brightness above 50% Min HW changes nothing

[ibehnam]

Thanks to BD, I can change the brightness of my external monitor using keyboard. But whether using keyboard or the brightness slider in the app, nothing changes for brightness >50% Min HW. It does work perfectly fine for <50% though. The video shows it best:

bd.mov

[waydabber]

Hi there, this is because when Enable combined dimming is enabled (under Settings/Displays), brightness 0-50% is software adjustment (to allow full dimming to black) and 50-100% is hardware backlight control via DDC protocol. It seems the DDC part does not work on your config for some reason.

The reasons might be:

• You are using the HDMI port to connect instead of USB-C
• You might be using a dock/adapter that does not relay DDC commands to the display
• The display does not support changing the backlight levels via DDC.

If you can't fix the DDC connection, then simply turn off Enable DDC communication under Settings/Displays for the given display and the app will utilize software dimming for the entire scale.

Hope this helps! :)

[ibehnam]

Thanks for your thorough explanation. I'm using a USB hub and that may be the culprit. That said, the same hub was fine under Windows (I could increase/decrease brightness programmatically). So maybe it's also a macOS limitation with some hubs.

[waydabber]

What kind of HUB is it?

[ibehnam]

This one: https://www.amazon.com/gp/product/B07WWLXY7X/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1?tag=stylingbyliz-20. Supposedly should support macOS.

[waydabber]

Well, the HUB might not pass DDC properly or macOS might have issues with it as it seems to have multiple video outputs for a single connection (probably uses MST?).

[DanielYang59]

Thanks for the spot-on reply. I'm also having this issue with my monitor :)