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Mac mini driving two LG UltraFine (5K) Display thunderbolt displays?

Anonymous Freak

Anonymous Freak

macrumors 603
Dec 12, 2002
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Cascadia
There are other differences in the file, but mostly related to the fact that one is connected by DisplayPort (and apparently the M1's GPU supports FreeSync!) and one via HDMI. There's a *LOT* of extra data in there, I haven't poured through it to look for potentially-privacy-concerning data.

The two displays are the same make/model. (Samsung U28E590)

Okay, nothing obviously privacy-concerning in the files (I didn't think there would be, but you never know,) *AND* I realized the last run was mis-matched monitors (a U24E590 instead of a U28,) and the HDMI one wasn't using a high-quality cable.

So, here you go, the ioreg data for both, and photos of both on the "test text image". With both set to full 3840x2160 resolution so that the text would guaranteed be 1:1.
 

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J

joevt

macrumors 604
Jun 21, 2012
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Anonymous Freak said:
There are other differences in the file, but mostly related to the fact that one is connected by DisplayPort (and apparently the M1's GPU supports FreeSync!) and one via HDMI. There's a *LOT* of extra data in there, I haven't poured through it to look for potentially-privacy-concerning data.

The two displays are the same make/model. (Samsung U28E590)

Okay, nothing obviously privacy-concerning in the files (I didn't think there would be, but you never know,) *AND* I realized the last run was mis-matched monitors (a U24E590 instead of a U28,) and the HDMI one wasn't using a high-quality cable.

So, here you go, the ioreg data for both, and photos of both on the "test text image". With both set to full 3840x2160 resolution so that the text would guaranteed be 1:1.
Click to expand...
Maybe it just detects FreeSync without supporting it?

The images don't look like chroma sub sampling. It's really noticeable when it exists. The rtings.com web page has good example images. Do your displays have an option to show the color format? My Dell P2415Q shows YPbPr or RGB but doesn't show if the YPbPr mode is using chroma sub sampling (it does use chroma sub sampling by default in Catalina when connected via HDMI 2.0 and doing 4K 60Hz - I think chroma sub sampling can be easily removed by going to 4K 30Hz and less easily removed by going to DisplayPort). I think the "log stream" command can show what the color format is set to when you change the resolution. The example at #136 shows a log message from com.apple.coreanimation:WindowServer that says 5120x1440 59hz YCbCr444_10bit but need more testing to prove that it is related to the actual output signal. The problem with log stream is that you don't always know what the log message you're looking for actually looks like so you have to create a predicate that captures lots of stuff and modify it to exclude spammed messages you don't care about, or you can try looking for messages that contain certain strings (maybe use case insensitive comparisons) (like graphics, coredisplay, framebuffer, RGB, 444, 422, 420) and hope you get what you want.

The ioreg did not get attached to your post.
 
J

joevt

macrumors 604
Jun 21, 2012
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Anonymous Freak said:
Whoops. Lets' try this again…

Edit: Nope, doesn't like it. Here's a pastebin link to it: ioreg_M1_displays.txt (Set to expire in two weeks. Get it while it's hot!)
Click to expand...
Got it, thanks. zipping using Compress in the Finder should work as an alternative.

I still don't know how to determine the pixel format/encoding but I did figure out that the sync rate numbers are fixed point numbers with 16 bits for the fractional part. So 3932160 = 60Hz and 8847360 = 135 kHz. I guess that should be sufficient to get the pixel clock.

If the Displays preferences panel has an HDR option, then getting an ioreg with it off and on to compare might help (but probably unlikely given what we've seen so far).

I wonder if the ioreg device tree plane has anything useful?
ioreg -p IODeviceTree -filw0 > ioreg_M1_devicetree.txt
The list of planes is:
Code: 
  |   "IORegistryPlanes" = {"IOPort"="IOPort","IOPower"="IOPower","IOService"="IOService","IOAccessory"="IOAccessory","IOUSB"="IOUSB","CoreCapture"="CoreCapture","IO80211Plane"="IO80211Plane","IODeviceTree"="IODeviceTree"}
IOPort and IOAccessory I think are specific to M1 Macs only (doesn't exist on my Intel Mac mini 2018).
 
AppleUserFromSoFL

AppleUserFromSoFL

macrumors newbie
Jan 20, 2021
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0
Deinocheirus said:
This is so frustrating. What I really want is a 48" 8K display from Apple with Apple display quality.

Nothing fits my needs. Multiple displays don't cut it unless you have at 3 (left, center, right) and nothing can drive 3 displays smoothly without help.

Even if I wanted to plunk down $5000 for Apple's best...its a 30" 6K display. Too big in the wrong direction. Elements too small.

Why am I so at odds with the entire display market?
Click to expand...
I Share your dismay with the display market. I want to run dual 5k's like everyone else or 3 5k's if that is even possible.
 
S

saulinpa

macrumors 65816
Jun 15, 2008
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Dkelly811 said:
Can I run one at 5k and one at 4K with some kind of HDMI adapter for the m1 mini?
Click to expand...
Not easy.

With the original LG you would need to inject the video into a TB stream. Theoretically possible as some have done it with an 2010 Mac Pros and a TB PCI-e add-on card.

The new LGs support displayport so should be able to go HDMI to DP to USB-C. https://www.amazon.com/dp/B0752D33PJ and https://www.amazon.com/AmazonBasics-Bi-Directional-USB-C-DisplayPort-Cable/dp/B081VK7Q94
 
J

joevt

macrumors 604
Jun 21, 2012
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Dkelly811 said:
Can I run one at 5k and one at 4K with some kind of HDMI adapter for the m1 mini?
Click to expand...
Maybe. You can try a club-3d CAC-1332 or SIIG HDMI to USB-C Port 4K 60Hz Converter Adapter.
The early model LG UltraFine 5K 27MD5KA would also require using a Thunderbolt 3 add-in card to convert DisplayPort to Thunderbolt (in that case you would use the CAC-1331 and loose USB functionality). The current model 27MD5KL can work directly with a a USB-C (non Thunderbolt) input.

M1 Macs don't let you create custom timings so you have to hope that the adapter gives a mode that is good enough. Intel Macs let you override the EDID using an override file (this is how SwitchResX adds custom timings).

A 4096x2304@59Hz mode might be preferable compared to 3840x3840 for example. But you might get stuck with something lower like 1440p? You have to try it to find out or find someone who has done this already with an M1 Mac.

These adapters don't support widths greater than 4K so you can't try 5K39Hz. You'll have to wait for a HDMI 2.1 to DisplayPort 1.4 adapter for that.

If the adapter doesn't present a mode you want to use, then you need a method to override the EDID. Below are some solutions that might work in that case:

The SIIG HDMI to DisplayPort 1.2 Converter 4Kx2K 60Hz lets you choose an EDID (but I don't think it will let you set a custom EDID).

There exists EDID adapters that let you copy an EDID. I don't know if there are any inexpensive ones with a USB or serial input that let you set an arbitrary EDID. This way you could add custom timings using a custom EDID.
https://fsrinc.com/fsr-products/product/dr-edid-manager-learner/category_pathway-143
Actually, this one seems interesting but it's out of stock (I don't know if the lower res versions can be reprogrammed with 4K60 timing):
https://www.gofanco.com/hdmi-edid-emulator-passthrough-adapter-3840x2160-pro-edid4k.html
The reprogrammer:
https://www.amazon.com/dp/B099M2J994?th=1
Here's one that seems interesting - maybe has more features than needed:
https://hdfury.com/product/4k-arcana-18gbps/
They have other EDID solutions:
https://www.hdfury.com/product-category/edid-solutions/
I think this one seems the best for 4K60 18Gbps with EDID editing:
https://www.hdfury.com/product/dr-hdmi-4k/
It's kind of disappointing that the EDIDs are limited to 256 bytes so you can't add DisplayID extension blocks but that's not necessary for what you want to do.
 
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Dkelly811

Dkelly811

macrumors member
Sep 24, 2017
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Your answer was literally so helpful. I thought I was a knowledgeable tech guy, but then you came along. I have the 27md5kl-b so running in 4K would just require the SIIG and a 4K quality HDMI cable correct?

I’d rather not mess with custom timing controllers unless you think I need to.

Please advise.
 
Dkelly811

Dkelly811

macrumors member
Sep 24, 2017
31
3
saulinpa said:
Not easy.

With the original LG you would need to inject the video into a TB stream. Theoretically possible as some have done it with an 2010 Mac Pros and a TB PCI-e add-on card.

The new LGs support displayport so should be able to go HDMI to DP to USB-C. https://www.amazon.com/dp/B0752D33PJ and https://www.amazon.com/AmazonBasics-Bi-Directional-USB-C-DisplayPort-Cable/dp/B081VK7Q94
Click to expand...
I do have a newer one, but the Amazon DP to USB C cable you listed is out of stock? Any other suggestion?
 
J

joevt

macrumors 604
Jun 21, 2012
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Dkelly811 said:
I have the 27md5kl-b so running in 4K would just require the SIIG and a 4K quality HDMI cable correct?
Click to expand...
Probably.

Dkelly811 said:
I’d rather not mess with custom timing controllers unless you think I need to.
Click to expand...
Such messing may be required if you get stuck with a max of 3840x2160 and you would prefer 4096x2304.

Dkelly811 said:
I do have a newer one, but the Amazon DP to USB C cable you listed is out of stock? Any other suggestion?
Click to expand...
That adapter won't include USB 2.0 like the CAC-1332 and similar SIIG adapters will. USB is used by the display for audio, camera, brightness control, and USB ports.
 
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Dkelly811

Dkelly811

macrumors member
Sep 24, 2017
31
3
joevt said:
Probably.


Such messing may be required if you get stuck with a max of 3840x2160 and you would prefer 4096x2304.


That adapter won't include USB 2.0 like the CAC-1332 and similar SIIG adapters will. USB is used by the display for audio, camera, brightness control, and USB ports.
Click to expand...
So do you suggest the CAC 1332 or the SIIG?
 
J

joevt

macrumors 604
Jun 21, 2012
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Dkelly811 said:
Any suggestions on a good 4K HDMI cable?
Click to expand...
I don't know how good it is. It should at least work. Monoprice has these slim cables - I like that they are not too thick and the connectors are not super long or thick.
https://www.monoprice.com/product?p_id=13590
https://www.monoprice.com/product?p_id=24187 has HDMI certification.
Maybe you can future proof with some 48Gbps cables which should be good enough for 4K (18Gbps).
https://www.monoprice.com/category/...s&v_Bandwidth_uFilter=48Gbps&TotalProducts=34

Dkelly811 said:
Would this cable work? Amazon Basics High-Speed 4K HDMI... https://www.amazon.com/dp/B014I8T0YQ?ref=ppx_pop_mob_ap_share
Click to expand...
It says 18Gbps so it should be enough.
 
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