T470 Two Displayports?

T430 - T470 and T530 - T570 series specific matters only
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chx1975
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T470 Two Displayports?

#1 Post by chx1975 » Sat Oct 07, 2017 2:46 pm

Is it possible to use a USB C-to-DisplayPort adapter and the DisplayPort connector on the Pro Dock at the same time ? I called tech support and was transferred back and forth and noone knows.

And no, the Ultra dock is no solution, it's an MST hub. It's painfully obvious the docking connector only has a single DP 1.2 connection running in it. But is it the same DP 1.2 output as the one routed into the USB C? It doesn't need to be , the GPU is triple display capable, after all. But then again, we are talking of Lenovo.

https://support.lenovo.com/de/en/solutions/pd029622 this doesn't have the T470 listed. http://s3.amazonaws.com/isby/lenovopart ... utions.pdf is mum on the topic. I tried. I really tried. No info anywhere.

To muddle the waters:
Boot Display Device

Values: ThinkPad LCD, USB Type-C, HDMI,Display on dock

Description: Select the display device that you want to activate at boot time. This selection is effective for boot time, password prompt, and ThinkPad Setup. USB Type-C corresponds to the USB Type-C connector on your computer. HDMI corresponds to the HDMI connector on your computer. Display on dock corresponds to the video connectors (such as the DisplayPort, DVI, or VGA connectors) on a docking station. Boot screen is cloned to all displays on dock.
that's four options while Intel 620 only supports three. One needs to give. How is this actually routed? To make things even worse some T470 have a 940MX in them (for sure my T25 will have) which, being Maxwell, is certainly capable of quad displays. Is that why there's a 940MX in the first place?? In which basement does Lenovo keep system diagrams and what's the URL to there :P ?

dr_st
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Re: T470 Two Displayports?

#2 Post by dr_st » Sat Oct 07, 2017 3:42 pm

chx1975 wrote:
Sat Oct 07, 2017 2:46 pm
And no, the Ultra dock is no solution, it's an MST hub.
It should still work well for dual display under Windows, although probably not in Linux (according to ThinkWiki).
chx1975 wrote:
Sat Oct 07, 2017 2:46 pm
It's painfully obvious the docking connector only has a single DP 1.2 connection running in it. But is it the same DP 1.2 output as the one routed into the USB C? It doesn't need to be , the GPU is triple display capable, after all. But then again, we are talking of Lenovo.
Although I don't have definitive proof, I will be very surprised if these are not separate DP 1.2 connections. They've been separate for all models starting from T410 generation.
chx1975 wrote:
Sat Oct 07, 2017 2:46 pm
that's four options while Intel 620 only supports three. One needs to give.
The Intel 620 supports all four, AFAIK, just not at the same time.

If anything, this suggests that Dock DP and USB-C DP are routed separately. Otherwise, there would be no reason to list them as separate options...
Current: X220 4291-4BG, T410 2537-R46, T60 1952-F76, T60 2007-QPG, T42 2373-F7G
Collectibles: T430s (IPS FHD + Classic Keyboard), X32 (IPS Screen)
Retired: X61 7673-V2V, A31p w/ Ultrabay Numpad
Past: Z61t 9440-A23, T60 2623-D3U, X32 2884-M5U

chx1975
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Posts: 84
Joined: Thu Mar 24, 2011 6:44 pm
Location: Vancouver, Canada

Re: T470 Two Displayports?

#3 Post by chx1975 » Sat Oct 07, 2017 3:45 pm

dr_st wrote:
Sat Oct 07, 2017 3:42 pm
They've been separate for all models starting from T410 generation.
Well, the dock up to T430 passthrough DP ports so the question wouldn't even arise -- things got this complicated because the Ultra is an MST hub instead of having two independent DisplayPort. If they regressed with the dock why not with the output routing?

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