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How to change brightness of external monitor in clamshell mode?

A

acousticbiker

macrumors 6502a
Original poster
Jun 28, 2008
982
199
I just upgraded from a 2020 Intel MBA to an M1 MBA. I had been using MonitorControl with the Intel MBA but with the change to an M1 MBA, that app no longer recognizes my Philips 329P9H (which the developer is aware of). I've tried:

  • Control Center: the Display brightness slider is grayed out and can't be toggled
  • System Prefs > Displays: I don't see a brightness slider
  • Monitor's on screen menu: Brightness is grayed out and can't be toggled
 
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MonitorControl is using macOS private framework, the OSD.framework, and because it is closed, we cannot re-compile it to an ARM version by ourselves. The fix is not possible before someone extract the universal binary of that private framework from Big Sur.
 
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Github tracking for this issue:
github.com

MonitorControl not working on Apple Silicon (M1) Macs · Issue #323 · MonitorControl/MonitorControl

Checklist I have searched for existing issues I have looked through the wiki I have updated MonitorControl to the latest version Describe the bug Installing MonitorControl on a MacBook Air with App...
github.com github.com

You can follow that thread to see if/when the issue is resolved. From what I'm seeing, it may be a bug in the OS itself. And as Gnattu said, we don't have control over internal Apple frameworks, so at this point, we can only wait for them to do something about it. This may be some minor revisions later. 11.1 beta doesn't seem to resolve this, either.
 
bill-p said:
Github tracking for this issue:
github.com

MonitorControl not working on Apple Silicon (M1) Macs · Issue #323 · MonitorControl/MonitorControl

Checklist I have searched for existing issues I have looked through the wiki I have updated MonitorControl to the latest version Describe the bug Installing MonitorControl on a MacBook Air with App...
github.com github.com

You can follow that thread to see if/when the issue is resolved. From what I'm seeing, it may be a bug in the OS itself. And as Gnattu said, we don't have control over internal Apple frameworks, so at this point, we can only wait for them to do something about it. This may be some minor revisions later. 11.1 beta doesn't seem to resolve this, either.
Click to expand...
This is not a "bug", this is a "feature". Because the use private frameworks is prohibited by Apple and they will offer no help for you to use those frameworks.
It works before because the developers of MonitorControl extract the binary of that framework 3 years ago using some undocumented method, and integrates that into the project. Obviously, that binary was made for Intel, not AS. To make it work for AS, we need to extract it from Big Sur again.
 
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Thanks, everyone, the details are over my head technically but I’m subscribed to that issue on GitHub to keep tabs.

Assuming a fix for MonitorControl is not imminent, anyone have tips for how I can control brightness in the meantime?
 
Well, it goes without saying... but I think you may have to use the controls on the monitor itself to achieve that in the mean time.
 
bill-p said:
Well, it goes without saying... but I think you may have to use the controls on the monitor itself to achieve that in the mean time.
Click to expand...
As I mentioned in my original post, the controls on the monitor are also grayed out (just for brightness, I can toggle the others).

Brighton Billy said:
System Pref > Display > Brightness doesn't work ?
Click to expand...
Also, as mentioned in my original post, there is no brightness toggle when I go to System Prefs > Displays

And another weird twist is that when I use the native MBA display, I can only change between the maximum and one notch below maximum brightness using the F1 and F2 keys - strange because the brightness in the Control Center (and Display prefs) is closer to the middle, which is where I prefer. The other function keys work and I can control brightness from Control Center and System Prefs > Displays in this case. This weirdness persists even after a reboot.
 
Last edited:
acousticbiker said:
As I mentioned in my original post, the controls on the monitor are also grayed out (just for brightness, I can toggle the others).
Click to expand...

Oh, you mean the OSK of the monitor itself is grayed out? That's very odd. Have you tried a different port?
 
bill-p said:
Oh, you mean the OSK of the monitor itself is grayed out? That's very odd. Have you tried a different port?
Click to expand...
I'm connecting via USB C and don't have an HDMI or Display Port cable to try those other ports on my monitor.
 
acousticbiker said:
As I mentioned in my original post, the controls on the monitor are also grayed out (just for brightness, I can toggle the others).


Also, as mentioned in my original post, there is no brightness toggle when I go to System Prefs > Displays

And another weird twist is that when I use the native MBA display, I can only change between the maximum and one notch below maximum brightness using the F1 and F2 keys - strange because the brightness in the Control Center (and Display prefs) is closer to the middle, which is where I prefer. The other function keys work and I can control brightness from Control Center and System Prefs > Displays in this case. This weirdness persists even after a reboot.
Click to expand...

Damn. If Apple doesnt fix it maybe you will have to buy a magic keyboard with the brightness keys.
 
I just spoke with an Apple Tech Support Senior Advisor and he said, independent of whether you're using an Intel or M1 Mac, brightness must be controlled on the monitor itself, that it has never been possible to do so in Display Preferences. Does that sound right? I no longer have my Intel Mac to test that.
 
Well, he's wrong. Apple's displays have no on-monitor control. For instance, I still have the Thunderbolt Display, and it has to be controlled within MacOS itself. That also goes for speaker volume as well.

I don't have your specific monitor, but I can confirm at least that some monitors work like this.

As a last resort, get yourself a USB-C > HDMI adapter and see if that allows you to adjust brightness via the monitor?
 
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