no display :(

[bja_au]

G'day,

I have a late 2012 mac mini on which I run Devuan/debian Linux mainly via an internal SSD which I installed a while back. I am also using Refind boot manager.

I used to have a Dell U2410 24" monitor connected via HDMI and it worked fine - max resolution of 1920x1200. I have now got a Dell U2720q 27" monitor (max resolution of 3840x2160) which I connect via mini-display/thunderbolt port (HDMI will only go upto 1920x1200) to the DisplayPort connector of the monitor.

My problem is that I get no display at boot time from the mini-display port! If I connect via HDMI (at the lower resolution) I do see the Refind menu however using the mini-display port nothing! But, if I let the default linux system boot it works!!!!

I have tried resetting the NVRAM and SMC but to no avail.

Any ideas please?
Thanks
BJA

 

[Fishrrman]

See:

Late 2012 Mac Mini 4K Video - Apple Community

discussions.apple.com

 

[adamcarvell]

i get this often when trying to wake the monitor i have to restart the mac mini to get it back very frustrating mine is also a late 2012 connected to the monitor via displayport.

 

[bja_au]

G'day again,

Thanks for the replies. I am getting like it says in the Apple Community article (thanks for the link) - 3840x2160@30Hz 30bits - only I am using a mini display port to DP cable, plus I don't see any boot info - the screen on wakes up when linux boots!
I did notice that it mentioned you need an "Active" adapter when they were discussing going from mini displayport to HDMI which I am not sure if my cable is so I am going to get one of those now. Will let you know how it goes ...

Thanks again
BJA

Edit: Ok tried an Active mini-displayport to HDMI (couldn't get a DP one) and get same results - no boot or Refind display/info but wakes up once it boots into the default linux

 

[Nguyen Duc Hieu]

It's not about the adapter.
Similar to the PC/laptop, I assume that pre-boot display signal is only sent out via the default output port, which is the HDMI port on the Mac Mini.

 

[bja_au]

It's not about the adapter.
Similar to the PC/laptop, I assume that pre-boot display signal is only sent out via the default output port, which is the HDMI port on the Mac Mini.

Sorry but that is not correct. Using my U2410 monitor works the same using either port.

 

[Nguyen Duc Hieu]

Sorry but that is not correct. Using my U2410 monitor works the same using either port.

Try changing the DP version on the Dell U2720q to DP 1,1 to see if it works for you.

 

[bja_au]

Try changing the DP version on the Dell U2720q to DP 1,1 to see if it works for you.

How do I do that please?

 

[Nguyen Duc Hieu]

How do I do that please?

Check the menu on the Dell to see whether you can change it.

 

[bja_au]

Check the menu on the Dell to see whether you can change it.

Unfortunately nothing there

 

[Nguyen Duc Hieu]

Unfortunately nothing there

Then there is no hope.

 

[bja_au]

G'day,
Well I have reached a solution which doesn't solve my problem but is usable. I installed OSX onto an old USB ext disc and when I boot from it OSX (eventually) comes up. The System Prefs/Display show a weird set of resolutions but installing SwitchResX shows that I am using 3840x2160@30Hz. Running OSX I get some flickering etc but if I run Linux it's fine! I still can't see Refind but I set it up (using old screen) to auto boot into my main Linux system.
Thanks all for your help and advice
BJA