Dell P2415Q unable to scale to higher res in retina

This is all I could find relative to displays in the release notes:

I suspect tho, that what you're seeing (o' pun!) is just an indication of an early beta where fleshed out video drivers are still being worked on for later release etc.

If the condition persists at the end of the beta cycle, feel free to file bugs.

I've the a similar problem with my MBP 15" Retina and an AOC Q2577PWQ that's a 25" with a resolution of 2560x1440; I've noticed that from the section "Monitor" on the Mac infos is recognized as a 30.5" so that the resolution is completely wrong and very bad.

This is a great monitor with a great resolution and used to work perfectly with El Capitan.

A similar situation with my DELL P2416D. No HiDPi

Exact same issue with a Dell P2715Q

If I reboot my MBP with the lid closed, the scaled resolutions are available and I can select 2560x1440 scaled. As soon as I either 1) open/close the lid 2) turn the monitor off/on or 3) put the system to sleep and wake it up. All scaled resolutions higher than 1920x1080 are gone and the screen has switched to 1920x1080 @2x. The only way to get the correct resolution back seems to reboot the system.

Same issue here. Same monitor.

For reference, here's some screenshots.

Immediately after booting (before lid is closed):

https://www.dropbox.com/s/3x9zc5ze4fw0gs4/Screenshot%202016-08-31%2000.29.12.png?dl=0

https://www.dropbox.com/s/sh5kdkas0w8dyz6/Screenshot%202016-08-31%2000.29.25.png?dl=0

After closing the lid (and persists if opened):

https://www.dropbox.com/s/7es2xfohbttipfj/Screenshot%202016-08-31%2000.30.03.png?dl=0

https://www.dropbox.com/s/4yjhrj4nal7gneh/Screenshot%202016-08-31%2000.30.24.png?dl=0

Running GM release.

Has anyone found a solution to this yet? Even on the release it's still broken.

I got an update on the Apple bug report I filed on this, and they said it would be fixed in a future update of Sierra. FWIW.

I wonder if it's fixed in the 10.12.1 beta, there seems to be nothing in the release notes about what changed in the .1 beta so the only way to find out would be to try it.

I am also very curious.

I can report that this is still not fixed in 10.12.1 PB 1.

FWIW, I have the exact same Dell P2415Q display and it is working fine for me at full retina (I never change the resolution to anything else) when in clamshell mode as well as when the display of my Mid-2014 MBPr 15" is open.

On a related note - this Dell display is great but has been notorious for one issue and that is that the display literally freezes and won't wake up if the Macbook has been asleep for a while. The power button on the display doesn't work - you have to remove power to it temporarily to get it to function again. This is a known intermittent problem and I'm happy to say that I think it's finally been fixed in Sierra as I've not had it happen since the release.

Interesting. When I close the lid to go clamshell, I see messages like "kernel - getCurrentDisplayMode for framebuffer 0 failed" and invalidating the display, and so on in the console (bring up the Console app and check). Do you see similar messages?

Yes, I also experience your freeze issue. I'm not sure if that problem has gone away with Sierra GM. I've seen it with PB's.

I just downloaded .1 beta 2 and can confirm this release fixes the display issues I was having with my Dell's