Author Topic: Displayport?  (Read 443 times)

Dave Yeo

  • Hero Member
  • *****
  • Posts: 3664
  • Karma: +77/-0
    • View Profile
Displayport?
« on: August 05, 2022, 07:34:37 am »
So this computer I'm using has a Sandybridge/Ivybridge graphics controller with a VGA and a Displayport ports, monitor has VGA and DVI ports and supports 1920x1200 as its native resolution.
For quite a while I was simply using the VGA connection, everything worked fine but slightly blurry.
Then I came across a Displayport to DVI passive connector so I tried that.
While the graphics were sharper, especially text mode, I came across these limitations. The screensaver would put the monitor to sleep but it would not wake up, forcing a reboot to awaken it. Same with SNAP and Panorama. Nothing I tried helped here, worked fine under Linux, which reported a HDMI connection. The other thing was I tried using Xfree86 using the VESA (VBE) driver, it simply did not find a graphics card at all, which was weird. Works fine with the VGA connector and an older Panorama/SNAP, newer ones seem to have done something to support UEFI where switching back to the WPS fails, a bit of drawing and then a full hang.
Just wondering about others experience with Displayport and OS/2. Perhaps a monitor that supports Displayport would be better, it seems that Displayport falls back to a DVI compatible protocol when used with a passive converter.

Andi B.

  • Hero Member
  • *****
  • Posts: 647
  • Karma: +8/-1
    • View Profile
Re: Displayport?
« Reply #1 on: August 05, 2022, 11:12:58 am »
Quote
Just wondering about others experience with Displayport and OS/2. Perhaps a monitor that supports Displayport would be better, it seems
I'm using DP out to DP in on the monitor since a while on this system. But I disabled all screen saving software long ago cause it didn't work. When I've the need for power saving (and don't wanted to switch off the whole system) I switch of the monitor with its remote control. Switching on afterwards works with OS/2. But not with Win7. As this simple test does not even work with Win I never tried to test anymore off this stuff.

Screen saver, actually switching monitor power on/off, never worked on this system. It worked on my old system when I patched black10x.zip to write the proper registers of my old ATI300 graphic card. But never on this newer system. Either with integrated (Intel) graphic nor with the PCIe Radeon 550.

Quote
that Displayport falls back to a DVI compatible protocol when used with a passive converter.
This is a feature of your motherboard/graphic chip. The signals are different between DP and DVI. Your mobo detects the DVI adapter and tells the graphic chip and the output transmitter to switch signals to DVI standard. That's a feature of some mobos/graphic cards but not mandatory. Your DP output at your mobo emulates DVI signals when you put a passive adapter on that. But it does not make a real fully compatible DVI interface out of it.

Quote
forcing a reboot to awaken it.
Maybe it's enough to disconnect the passive adapter and reconnect it again. But as it's an emulated DVI it will work different on different mobo/graphic cards. I think you would need reports from people with exactly the same motherboard.



Dariusz Piatkowski

  • Hero Member
  • *****
  • Posts: 1135
  • Karma: +24/-0
    • View Profile
Re: Displayport?
« Reply #2 on: August 05, 2022, 04:26:21 pm »
Hi Dave,

I'm afraid I cannot add much in terms of a "fix", but I will say this is interesting because having set up my dual display config here (Dell DU2412M) and being fed by my old trusty ATI X850XT PE, I am dealing with 1 of the units being hooked up through DVI and the 2nd one through VGA.

This is primarily a limitation of the current SNAP drivers, which do not support the ATI card's dual DVI ports to drive matching DVI ports on the display units.

The end result is that the VGA connected 2nd display is a little fuzzier (barely there, but my eyes pick this stuff up, so I can see it) and it does get slightly impacted by the VGA port's 'Pixel Clock' and 'Phase' settings. This sometimes results in that tell-tale noise when you display some dithered colour & texture combinations on the screen. Again, no biggie...but heck, with modern day hardware why suffer like this??? LOL

So point being, I have been meaning to try the monitor's DisplayPort as well, would need to use a DVI to DP connector, etc, but I'm curious how that might pan out?

Dave Yeo

  • Hero Member
  • *****
  • Posts: 3664
  • Karma: +77/-0
    • View Profile
Re: Displayport?
« Reply #3 on: August 06, 2022, 07:52:41 am »
Hi Andi, so it seems to be a limitation of emulating DVI, makes sense.
As for the screensaver, it might wel work for you now given a recent Panorama.
I'll attach a simple test program, run "panodpms c" to see the capabilities of your system. Panoutil.cmd is a safe way to test, it should turn off your monitor and wait till you press a key and then turn it back on, if it works, then the most recent screensaver will work as well. Note that now a days only on and off make sense with LCD monitors.

Hi Dariusz, I'd guess the DVI to Displayport adapter might work, you'd have to test, might only be available as an active adapter, hopefully simply using USB power. Let us know if you ever try it. 

ivan

  • Hero Member
  • *****
  • Posts: 1363
  • Karma: +15/-0
    • View Profile
Re: Displayport?
« Reply #4 on: August 06, 2022, 10:08:39 am »
Ican't help wondering why people keep on using something designed to prevent phosphor burn in on CRT monitors when it doesn't work on modern LCD panels.  I gave up using a screen saver back in 1990 when I pensioned off my CRT monitor for a 28" LCD unit.

As for using the DISPLAY port, I started using that when I built my first third generation Ryzen computer (MSI B550-A Pro board with a AMD Ryzen 3 Pro 4350G CPU), coupled with a Samsung S24E650 LCD monitor (display port to display port cable supplied by Samsung).  It worked very well during the testing phase but I have since gone to using HDMI through a 4 port USB/HDMI switch to allow switching all the computers on the network.

Dariusz Piatkowski

  • Hero Member
  • *****
  • Posts: 1135
  • Karma: +24/-0
    • View Profile
Re: Displayport?
« Reply #5 on: August 06, 2022, 02:58:00 pm »
Hi ivan,

I can't help wondering why people keep on using something designed to prevent phosphor burn in on CRT monitors when it doesn't work on modern LCD panels.  I gave up using a screen saver back in 1990 when I pensioned off my CRT monitor for a 28" LCD unit....

Well, there is still that power use part of the equation...no? LOL ;) If you want to be either ECO friendly, or wallet friendly, the real DPMS option allows the display to go into power-saving mode...and for my Dell units that's a difference of 30W (operating) vs 0.5W (active-off).

Dave Yeo

  • Hero Member
  • *****
  • Posts: 3664
  • Karma: +77/-0
    • View Profile
Re: Displayport?
« Reply #6 on: August 06, 2022, 04:31:13 pm »
Exactly the same here, power savings on this old Samsung SyncMaster 243T is from less then 75 watts (74?) to 2 watts, which adds up

Martin Iturbide

  • OS2World NewsMaster
  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3630
  • Karma: +34/-0
  • Your Friend Wil Declares...
    • View Profile
    • Martin's Personal Blog
Re: Displayport?
« Reply #7 on: August 06, 2022, 06:22:30 pm »
Ican't help wondering why people keep on using something designed to prevent phosphor burn in on CRT monitors when it doesn't work on modern LCD panels.

I love screen savers. I know that all those "tree huggers hippies" are right when they say that is just better for the earth to automatically turn off the monitor, but I just loved the old Johnny Castaway;D ;D ;D

Regards
Martin Iturbide
OS2World NewsMaster
... just share the dream.

ivan

  • Hero Member
  • *****
  • Posts: 1363
  • Karma: +15/-0
    • View Profile
Re: Displayport?
« Reply #8 on: August 06, 2022, 07:02:04 pm »
I know what you all are saying but my monitors have a little button at the bottom right corner which when pressed the screen goes blank (about 0.005W power draw) and when pressed again it springs to life.  I can't ask for much better than that.

Andreas Schnellbacher

  • Hero Member
  • *****
  • Posts: 794
  • Karma: +14/-0
    • View Profile
Re: Displayport?
« Reply #9 on: August 06, 2022, 10:36:07 pm »
Yes, I also often use the Power "button" of the LCD monitor, as I did for the CRT (can't really remember). The screen saver app works here with VGA, HDMI, DVI connectors. Haven't tried with a DVI - DP converter, due to lack of an adapter. The on-board jacks are VGA, HDMI and DVI, the monitor has them all: VGA, Composite,  HDMI, DVI, DP.

All these on-board connectors work with the screen saver (only tried blank screen). Haven't tested another machine with DP, but may follow in far future.

I had the LCD for a long time connected via VGA (was another machine with a Matrox), but then have also tried other interfaces. It took a while, but now I think the blurry display of an analog connection looks worse. Of course, monitor settings have to be adapted. I have both Brightness and esp. Contrast set to lower values.

Neil Waldhauer

  • Hero Member
  • *****
  • Posts: 839
  • Karma: +21/-0
    • View Profile
    • Blonde Guy
Re: Displayport?
« Reply #10 on: August 07, 2022, 03:27:49 pm »
I have a machine with Display port. The difference in sharpness at 1920 x 1200 is striking compared to Display port through a good Startek DisplayPort to VGA adapter. I'm overdue for an upgrade. HDMI seems to be the best option, but the world seems to be moving to USBc for video.
Expert consulting for ArcaOS, OS/2 and eComStation
http://www.blondeguy.com