Author Topic: Display-port and HDMI  (Read 784 times)

Eugene Tucker

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Display-port and HDMI
« on: October 27, 2021, 09:23:27 pm »
Display-port and HDMI for video. Anyone ever get these working or is anyone working on it. More of the newer mother boards only support these. gone are DVI and VGA ports.
« Last Edit: October 27, 2021, 10:29:46 pm by Martin Iturbide »

Roderick Klein

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Re: Display-port and HDMI
« Reply #1 on: October 27, 2021, 11:11:41 pm »
Good news they just work. They are video driver agnostic. The video hardware deals with the HDMI port.
When you connect an LCD screen to a HDMI port at startup the Panorama driver will work just fine with HDMI port.


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Martin Iturbide

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Re: Display-port and HDMI
« Reply #2 on: October 28, 2021, 12:36:51 am »
Hi

I think that on desktop computer it works. I had a PC with a NVidia card with only HDMI outputs and it worked. But what about laptops? Is there a way to enable/disable the HDMI/DisplayPort on those? I haven't tested that enough.

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Martin Iturbide
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Doug Bissett

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Re: Display-port and HDMI
« Reply #3 on: October 28, 2021, 08:06:52 am »
Some years ago, I played with HDMI, and Display Port, on my Lenovo ThinkPad T510, and L530. I don't recall having any video problems using a TV as a screen. You do need to know how to switch, using the Fn key combination, and that probably needs to be done BEFORE starting to boot OS/2.

Andi B.

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Re: Display-port and HDMI
« Reply #4 on: October 28, 2021, 09:16:31 am »
DisplayPort works and is preferred.

But as usual with OS/2 it depends on what the BIOS offers. I talk about Panorama as SNAP only supports very old hardware. Usually the BIOS scans on which connector which monitor is attached and makes some decisions. Means if you have a monitor attached on DisplayPort it uses it. If you have a monitor attached at HDMI BIOS uses it. If there are monitors attached to both interfaces usually DP is preferred. There are also some settings in BIOS which affect which interface should be preferred and used. This is all done long before any driver (gengradd) is involved. So boot up (cold boot) after all cables are in place. Don't expect switching between interfaces on the fly with CTRL-ALT-DEL only.

Usually DisplayPort supports all resolutions while on older systems HDMI is not able to support f.i. 4k/60Hz even when the graphic chip can do it.

Another question is - will the BIOS offer the capabilities it detects from the interface, the monitor and the graphic chip in a form Panorama can use it? It depends. I've a system with build in Intel graphic and DP, HDMI and analog interfaces. It can handle 4k / 60Hz on DP and Win can use it. On HDMI only 4k / 30Hz is possible as HDMI at that time could not handle the necessary bandwidth and the BIOS knew this. Of course these modes work in Win. But the BIOS does not offer these capabilities in a form Panorama can use it. No more than WQHD was possible. So I had to install a PCIe graphic card with an integrated BIOS which does it right. DP works fine on this.

Roderick Klein

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Re: Display-port and HDMI
« Reply #5 on: October 28, 2021, 09:23:21 am »
Some years ago, I played with HDMI, and Display Port, on my Lenovo ThinkPad T510, and L530. I don't recall having any video problems using a TV as a screen. You do need to know how to switch, using the Fn key combination, and that probably needs to be done BEFORE starting to boot OS/2.

Some laptops in the BIOS still support this functionality to use the Fn keys to switch to the external display port when the ArcaOS has not yet started.

Note that on systems booted in UEFI mode this functionality is gone. Its not part of the UEFI specs best I can tell!

And you will need with UEFI boot a video driver that talks to the video chipset directly to be able to switch.

Roderick

Eugene Tucker

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Re: Display-port and HDMI
« Reply #6 on: October 28, 2021, 12:52:13 pm »
Thank you to all for your responses I will be experimenting with my system.

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Re: Display-port and HDMI
« Reply #7 on: October 28, 2021, 03:33:23 pm »
DisplayPort works and is preferred.

But as usual with OS/2 it depends on what the BIOS offers. I talk about Panorama as SNAP only supports very old hardware. Usually the BIOS scans on which connector which monitor is attached and makes some decisions. Means if you have a monitor attached on DisplayPort it uses it. If you have a monitor attached at HDMI BIOS uses it. If there are monitors attached to both interfaces usually DP is preferred. There are also some settings in BIOS which affect which interface should be preferred and used. This is all done long before any driver (gengradd) is involved. So boot up (cold boot) after all cables are in place. Don't expect switching between interfaces on the fly with CTRL-ALT-DEL only.

Usually DisplayPort supports all resolutions while on older systems HDMI is not able to support f.i. 4k/60Hz even when the graphic chip can do it.

Another question is - will the BIOS offer the capabilities it detects from the interface, the monitor and the graphic chip in a form Panorama can use it? It depends. I've a system with build in Intel graphic and DP, HDMI and analog interfaces. It can handle 4k / 60Hz on DP and Win can use it. On HDMI only 4k / 30Hz is possible as HDMI at that time could not handle the necessary bandwidth and the BIOS knew this. Of course these modes work in Win. But the BIOS does not offer these capabilities in a form Panorama can use it. No more than WQHD was possible. So I had to install a PCIe graphic card with an integrated BIOS which does it right. DP works fine on this.

This agrees with my experience. I have many systems with DisplayPort, and all work as well as the VGA. Sometimes there is an additional resolution available with DisplayPort. But my monitor is inadequate to test the higher than HD resolutions.

Your information also suggests that Ctrl-Alt-Del will find new resolutions in a future ArcaOS system that supports UEFI. This needs to be tested, of course.
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Re: Display-port and HDMI
« Reply #8 on: October 28, 2021, 04:59:44 pm »
Note that on systems booted in UEFI mode this functionality is gone. Its not part of the UEFI specs best I can tell!

And you will need with UEFI boot a video driver that talks to the video chipset directly to be able to switch.

Roderick

I wonder if there is something like a standard UEFI video driver providing standard services (much like the legacy BIOS) and that has an interface that could be invoked by an OS video driver.
One of the problems would be that UEFI services and drivers are all 64-bit code (as far as I know). I don't know how you would call 64-bit code from 32-bit code (or even 16-bit code).

Roderick Klein

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Re: Display-port and HDMI
« Reply #9 on: October 28, 2021, 05:44:18 pm »
Basically from what I can tell you have UEFI video services. But once the system boots and the OS takes over, you are left with a video framebuffer at a fixed resolution to write to.
Unless you have a native video driver to talk to the chipset.



Roderick


Dave Yeo

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Re: Display-port and HDMI
« Reply #10 on: October 28, 2021, 05:53:12 pm »
One of the problems would be that UEFI services and drivers are all 64-bit code (as far as I know). I don't know how you would call 64-bit code from 32-bit code (or even 16-bit code).

I have a Windows 8 tablet that only supports 32 bit UEFI, and researching, it seems common on the older Atom tablets. I can boot Linux on it (the DFSee Puppy release) though without any kind of keyboard support, at least without a powered hub as the tablets USB port doesn't have enough power to run a USB stick and keyboard. Touchscreen acts like a mouse.
For us, it seems that we can do the 64bit boot by switching back to 32 bit mode very early in the boot process after setting up the hardware.