Dell P2715Q working about brightnessmenulet

[cheemeng]

Yea but MonitorControl doesn't have a "Follow Main Screen" option 😔

In any case thanks @falcn for introducing me to MonitorControl... !

[jryio]

Agreeing here. Just tested. Working perfectly. Thanks so much for the updated app!

[falcn]

Not working over DisplayPort/DisplayPort. Sliders are not active, any attempts to enter values manually set brightness/contrast to 0%/25%. I have hardware revision A02. Separate ddcctl works as expected, but cannot read current values.

[wagenet]

@falcn Huh, that's quite strange. It works fine for me on a USB-C > DP cable. Must be something different when not going over a USB-C AltMode.

[falcn]

I've discovered that I cannot set brightness below 25% using DDC (probably a safety feature of a monitor), so aforementioned 0/25 means that app probably sets brightness/contrast to 0/0, which makes sense: since it can't read anything from a monitor, it only allows to set value on a scale from 0 to 0.

Other apps work because they don't rely on reading current/max values from a monitor, they use hardcoded scale 0..100.

Adding a "if reading over DDC fails, assume that max is 100" will fix it.

[falcn]

I currently use this app to control brightness and contrast https://github.com/the0neyouseek/MonitorControl

My hardware is a 12" Macbook, P2715Q rev A02 running at 60hz, USB-C to Displayport hub http://a.co/dGZdgqd and a cable from the same company.

[wagenet]

@falcn I'd guess that the hub may be the issue in this case.

[cheemeng]

Not working for me as well... tried both Thunderbolt ports (no external hubs) to DP. MBP-r 13", mid-2014. P2715Q.

The MonitorControl app that falcn mentioned works for me too!

[falcn]

Any app that does not depend on reading current values work. As for why reading fails for certain monitors, I think it depends on a hardware revision. You can see yours on the back of the monitor, below the s/n.

[cheemeng]

OK I have swapped the monitor with a P2415Q rev A04. Does not work too. Shall I open it as a new issue? Because P2415Q is marked as working in the README

[falcn]

@cheemeng Interesting. A04 is the latest revision, AFAIK. What else could it be? Anyway, app could be easily modified to support any "write-only" monitors, but I'm content with MonitorControl, which already does it, and seems to be actively developed.

[falcn]

It's off topic, but, if you want to control sound volume, you should know that P2715Q doesn't support changing sound volume over DDC, so you need some kind of audio proxy.

Your options are: free but somewhat abandoned Soundflower+SoundFlowerBed, or commercial Sound Control ($10)