MP 7,1 AMD Radeon Pro 580X + LG 10bit HDR issues

[gabrielefx]

Hi all,

I've bought a Mac Pro 7.1 with the Radeon Pro 580X.
I've installed Windows 10 Pro and I want to use the Radeon Pro 580X thunderbolt 3 ports with my LG 5Kx2K 10 bit monitor.
My monitor is the model LG 34WK95U-W HDR10-HDR600 compatible.

Unfortunately the Radeon Pro 580X has a lot of issues with this monitor and thunderbolt 3 ports. Setting Windows 10 in HDR mode the monitor crashes, I have to unplug the power cord to reboot it. The thunderbolt 3 cable is ok, it's the original one provided by LG. I also tested other brands certified tb3 cables.
The second tb3 port (on top) is free, the other two (on the back) are free too.

Booting my Mac Pro 7.1 with Windows 10 Pro (bootcamp) the monitor sometime doesn't respond if it's set to Displayport 1.4, I have to set it to Displayport 1.2
After the booting I can force the monitor to run with Displayport 1.4, finally on Windows 10 Pro I can see the HDR option but trying to enable it will crash the LG monitor. No issues on MacOS and Displayport 1.4 but I can't test the HDR option.

It seems the Radeon Pro 580X isn't compatible with HDR 10 bit option on Windows 10 using the thunderbolt 3 ports.
It's very strange because on MacOS this gpu can display HDR output through the thunderbolt ports on two Apple XDR monitors at 6K 60Hz.
I think the AMD Radeon Pro 580X drivers aren't capable to display 10 bit HDR signal through the thunderbolt 3 on Windows 10.

I attached here a print screen of the various Windows 10 driver settings. As you can see the properties show different values in resolutions. AMD panel says the monitor has a maximum resolution of 3840x2160 pixels. The Windows 10 panel shows 5120x2160 but the detailed graphic card informations show 2560x2160 pixels.

On the same system I've installed also 2 RTX2080Tis working perfectly with this LG monitor at 5Kx2K HDR 10bit using the displayport cable.

Is anyone here using this monitor?

Regards

 

[mattspace]

It seems the Radeon Pro 580X isn't compatible with HDR 10 bit option on Windows 10 using the thunderbolt 3 ports.
It's very strange because on MacOS this gpu can display HDR output through the thunderbolt ports on two Apple XDR monitors at 6K 60Hz.
I think the AMD Radeon Pro 580X drivers aren't capable to display 10 bit HDR signal through the thunderbolt 3 on Windows 10.

The Radeon "Pro" 580 is just a normal Radeon 580 - do those get 10 bit output on Windows on a PC? Or is 10 bit exclusive to real "Pro" (eg full eECC RAM and chipset) GPU's with a "Pro" driver?

 

[joevt]

10 bpc and HDR should not be a problem with the 580X.

Maybe try avoiding Thunderbolt connection - use DisplayPort instead.
With Thunderbolt, it might be trying to use dual DisplayPort 1.2 instead of single DisplayPort 1.4.
In macOS, you can find out what the connection type is using the AGDCDiagnose command. GPU-Z advanced tab is not as detailed.

 

[gabrielefx]

10 bpc and HDR should not be a problem with the 580X.

Maybe try avoiding Thunderbolt connection - use DisplayPort instead.
With Thunderbolt, it might be trying to use dual DisplayPort 1.2 instead of single DisplayPort 1.4.
In macOS, you can find out what the connection type is using the AGDCDiagnose command. GPU-Z advanced tab is not as detailed.

The Radeon Pro 580X hasn't any displayport output and through the HDMI output can't handle a 5Kx2K resolution
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The Radeon "Pro" 580 is just a normal Radeon 580 - do those get 10 bit output on Windows on a PC? Or is 10 bit exclusive to real "Pro" (eg full eECC RAM and chipset) GPU's with a "Pro" driver?

The Apple MPX Radeon Pro 580X uses AMD professional drivers on Windows 10 (bootcamp)

 

[Krevnik]

The Radeon Pro 580X hasn't any displayport output and through the HDMI output can't handle a 5Kx2K resolution

I think he means using the DisplayPort connection on the display itself using a USB-C to DisplayPort cable. That will at least avoid using a Thunderbolt connection to the display.

----

Although I'll point out that this particular monitor has a pretty iffy record with Mac users as it is. I'm not terribly surprised there's bugs.

 

[XNorth]

The culprit seems to be a bug with DisplayPort 1.4 in Catalina 10.15.4. HDR is supported with DP 1.4 and Catalina 10.15.4, but its so buggy and crappy, I don't use. It has nothing to do with the 580X. I have the same LG 34 UltraWide monitor primarily using it with the MBP 16" on TB 3.

Everything works and looks great with DP 1.2, but HDR isn't supported with DP 1.2 and Catalina, so there is no HDR mode option in the Displays preferences.

Hot switching to DP 1.4 on the LG freezes the display with a black screen. Unplugging the LG and powering it back on, the HDR mode kicks in with DP 1.4, but the display looks washed out, low resolution, and most HDR content looks over-saturated.

I have reported this bug to Apple.

Edit: In HDR mode with Dp 1.4, the maximum resolution of the LG is downgraded to 3840 x 2160, which is only 16:9 wide. In DP 1.2, the display is capable of its native 5120 x 2160 ultrawide 21:9. So DP 1.4 in Catalina turns my ultrawide 4.5K monitor into an average 4K 16:9 monitor.

 

[joevt]

The culprit seems to be a bug with DisplayPort 1.4 in Catalina 10.15.4. HDR is supported with DP 1.4 and Catalina 10.15.4, but its so buggy and crappy, I don't use. It has nothing to do with the 580X. I have the same LG 34 UltraWide monitor primarily using it with the MBP 16" on TB 3.

Everything works and looks great with DP 1.2, but HDR isn't supported with DP 1.2 and Catalina, so there is no HDR mode option in the Displays preferences.

Hot switching to DP 1.4 on the LG freezes the display with a black screen. Unplugging the LG and powering it back on, the HDR mode kicks in with DP 1.4, but the display looks washed out, low resolution, and most HDR content looks over-saturated.

I have reported this bug to Apple.

Edit: In HDR mode with Dp 1.4, the maximum resolution of the LG is downgraded to 3840 x 2160, which is only 16:9 wide. In DP 1.2, the display is capable of its native 5120 x 2160 ultrawide 21:9. So DP 1.4 in Catalina turns my ultrawide 4.5K monitor into an average 4K 16:9 monitor.

Use the AGDCDiagnose command to see how the connection changes between modes. Use the unplug method/reset power method when switching modes to be sure the mode is setup properly. Then set the resolution. Then get the AGDCDiagnose output for that mode.

The 5K2K display should be able to support the following modes:

• HBR2 (4K 10 bpc)
• HBR3 (5K2K 10 bpc)
• dual HBR2 (5K2K 10 bpc) (Thunderbolt only)

HBR3 should be enough for HDR at full resolution. The AGDCDiagnose output will show why you're not getting full resolution.

 

[gabrielefx]

Use the AGDCDiagnose command to see how the connection changes between modes. Use the unplug method/reset power method when switching modes to be sure the mode is setup properly. Then set the resolution. Then get the AGDCDiagnose output for that mode.

The 5K2K display should be able to support the following modes:

• HBR2 (4K 10 bpc)
• HBR3 (5K2K 10 bpc)
• dual HBR2 (5K2K 10 bpc) (Thunderbolt only)

HBR3 should be enough for HDR at full resolution. The AGDCDiagnose output will show why you're not getting full resolution.

With AGDCDiagnose -a I read these two significative values:

Window (Active) 2560 x 2160
Window (Scaled) 5120 x 2160

These are the same values I read on Windows 10 advanced graphic panel. AFAIK thunderbolt 3 cable sends two DisplayPort 1.2 streams of 2560x2160 pixels each.
Probably the LG 5Kx2K monitor can't handle these two streams + HDR metadata using the thunderbolt 3 cable.
I don't know if it's an AMD driver missing feature or the monitor needs a firmware compatible with the Apple/AMD MPX (thunderbolt 3) gpus.

 

[Krevnik]

So, because it is using two streams, you can try something like this:

Cable Matters 32.4Gbps USB C to DisplayPort 1.4 Cable 6 ft, Support 8K 60Hz / 4K 144Hz (USB-C to DisplayPort, USB C to DP Cable) in Black - Thunderbolt 4 / USB4 Compatible with iPhone 15, MacBook, XPS

Experience Vivid 4K Video over DisplayPort The Cable Matters USB Type-C to DisplayPort Cable supports the newest release computers and smartphones with USB-C or Thunderbolt 3 up to 4K 60Hz UHD display monitors with DisplayPort. Experience the vibrant video and authentic audio supported by monitor...

www.amazon.com

Moshi USB C to DisplayPort Cable 1.5m/5ft, Support 5K@60 Hz, 4K HDR, VESA Certified, Aluminum Housing, Thunderbolt 3 Compatible (Ensure Monitors Accept DisplayPort Signal)

Supports up to 5K video resolution with 4:4:4 chroma subsampling, supports High Dynamic Range & Bi-directional support

www.amazon.com

The idea is by using the DisplayPort input on the back, you should be able to force a single 1.4 stream.

 

[joevt]

With AGDCDiagnose -a I read these two significative values:

Window (Active) 2560 x 2160
Window (Scaled) 5120 x 2160

These are the same values I read on Windows 10 advanced graphic panel. AFAIK thunderbolt 3 cable sends two DisplayPort 1.2 streams of 2560x2160 pixels each.
Probably the LG 5Kx2K monitor can't handle these two streams + HDR metadata using the thunderbolt 3 cable.
I don't know if it's an AMD driver missing feature or the monitor needs a firmware compatible with the Apple/AMD MPX (thunderbolt 3) gpus.

Look at the part in the AGDCDiagnose output that lists the ports of the GPU. You'll see two connections of HBR2. HBR2 is the link rate for DisplayPort 1.2 which does not support HDR but HDR is supported if the DisplayPort version is 1.4 so look at the DPCD registers - version 1.4 should be listed in there (DisplayPort 1.4 can use HBR3 link rate and lower).

Repeat your tests with different settings (DisplayPort 1.4 enabled and disabled) and connections (DisplayPort input and Thunderbolt input).

HDR is only 10 bpc. A dual HBR2 connection over Thunderbolt 3 can supply that easily (even at larger 5120 x 2880 resolution of LG UltraFine 5K display) but the HDR feature requires DisplayPort 1.4 version.

Zip and post the AGDCDiagnose outputs showing the various connections and settings so we can compare.
[automerge]1585067929[/automerge]

So, because it is using two streams, you can try something like this:

Cable Matters 32.4Gbps USB C to DisplayPort 1.4 Cable 6 ft, Support 8K 60Hz / 4K 144Hz (USB-C to DisplayPort, USB C to DP Cable) in Black - Thunderbolt 4 / USB4 Compatible with iPhone 15, MacBook, XPS

Experience Vivid 4K Video over DisplayPort The Cable Matters USB Type-C to DisplayPort Cable supports the newest release computers and smartphones with USB-C or Thunderbolt 3 up to 4K 60Hz UHD display monitors with DisplayPort. Experience the vibrant video and authentic audio supported by monitor...

www.amazon.com

Moshi USB C to DisplayPort Cable 1.5m/5ft, Support 5K@60 Hz, 4K HDR, VESA Certified, Aluminum Housing, Thunderbolt 3 Compatible (Ensure Monitors Accept DisplayPort Signal)

Supports up to 5K video resolution with 4:4:4 chroma subsampling, supports High Dynamic Range & Bi-directional support

www.amazon.com

The idea is by using the DisplayPort input on the back, you should be able to force a single 1.4 stream.

The moshi cable can also be used to force a single DisplayPort stream to the USB-C port (the Cable matters cable does not indicate bidirectional capability - there's a cable from Monoprice that is bidirectional). Since the 580X only has USB-C outputs, you'll need to pair the bidirectional cable with a USB-C to DisplayPort 1.4 adapter if you want to try this connection method.

 

[gabrielefx]

What do you think about this cable?

6ft USB C to DisplayPort 1.4 Cable 8K/4K - USB-C Display Adapters | Display & Video Adapters | StarTech.com Canada

6ft/1.8m USB C to Displayport 1.4 Cable Adapter - 4K/5K/8K USB Type C to DP 1.4 Monitor Video Converter Cable - HDR/HBR3/DSC | Canada

www.startech.com

[automerge]1585124798[/automerge]

Look at the part in the AGDCDiagnose output that lists the ports of the GPU. You'll see two connections of HBR2. HBR2 is the link rate for DisplayPort 1.2 which does not support HDR but HDR is supported if the DisplayPort version is 1.4 so look at the DPCD registers - version 1.4 should be listed in there (DisplayPort 1.4 can use HBR3 link rate and lower).

Repeat your tests with different settings (DisplayPort 1.4 enabled and disabled) and connections (DisplayPort input and Thunderbolt input).

HDR is only 10 bpc. A dual HBR2 connection over Thunderbolt 3 can supply that easily (even at larger 5120 x 2880 resolution of LG UltraFine 5K display) but the HDR feature requires DisplayPort 1.4 version.

Zip and post the AGDCDiagnose outputs showing the various connections and settings so we can compare.
[automerge]1585067929[/automerge]

The moshi cable can also be used to force a single DisplayPort stream to the USB-C port (the Cable matters cable does not indicate bidirectional capability - there's a cable from Monoprice that is bidirectional). Since the 580X only has USB-C outputs, you'll need to pair the bidirectional cable with a USB-C to DisplayPort 1.4 adapter if you want to try this connection method.

It's crazy to use two adapters usb-c-->Displayport male + Displayport female-->usb-c.
With just one thundebolt 3 cable I could use a 6K XDR monitor on MacOS, probably it won't work on Windows 10.
I think the LG monitor, as I wrote before, can't accept a 5Kx2K 10 bit digital video signal + HDR metadata through the thunderbolt 3 input. Chipset? Firmware? AMD drivers? Bootcamp drivers? Windows kernel? I don't know.
I will check with the latest Catalina 10.15.4

 

[joevt]

What do you think about this cable?

It doesn't say it is bidirectional. If you only want to connect from USB-C source to DisplayPort display, then it should be fine.

It's crazy to use two adapters usb-c-->Displayport male + Displayport female-->usb-c.

I don't know of any other method to connect a Thunderbolt display to a Thunderbolt computer using USB-C DisplayPort alt mode instead of Thunderbolt alt mode.

With just one thundebolt 3 cable I could use a 6K XDR monitor on MacOS, probably it won't work on Windows 10.

I don't think Windows can do dual HBR3 over Thunderbolt for 6K (Apple has special firmware or software to support that on their Titan Ridge Thunderbolt 3 controllers) - so you need a GPU that supports DSC to get 6K in Windows (such as RTX or Navi).

I think the LG monitor, as I wrote before, can't accept a 5Kx2K 10 bit digital video signal + HDR metadata through the thunderbolt 3 input. Chipset? Firmware? AMD drivers? Bootcamp drivers? Windows kernel? I don't know.
I will check with the latest Catalina 10.15.4

We won't know without info from AGDCDiagnose. 10.15.4 has changes related to HDR. It also has changes related to wide aspect ratio displays. And I think it has a change for this display (if it is product ID 0x7721).

 

[gabrielefx]

Hi,
I've attached here the diagnose text.
Also today I've installed the new Catalina release. The HDR doesn't work at 5120x2160 resolution, it works only using the Radeon Pro 580X HDMI output.
Unfortunately no Apple apps use properly the HDR option, Safari or Chrome don't show the correct gamma or high dinamic range when watching videos within Youtube or Apple TV+
On Windows 10 and bootcamp the AMD drivers also don't use the HDR feature (when the HDR is on) watching Youtube videos at 4K HDR. In fact clicking on the full screen button nothing happens, the Youtube 4K HDR videos are washed.
If I do the same with my Nvidia RTX2080Ti (installed on the same system) I see clearly changing the color gamma and brightness using the Youtube full screen option.

 

[joevt]

Hi,
I've attached here the diagnose text.
Also today I've installed the new Catalina release. The HDR doesn't work at 5120x2160 resolution, it works only using the Radeon Pro 580X HDMI output.
Unfortunately no Apple apps use properly the HDR option, Safari or Chrome don't show the correct gamma or high dinamic range when watching videos within Youtube or Apple TV+
On Windows 10 and bootcamp the AMD drivers also don't use the HDR feature (when the HDR is on) watching Youtube videos at 4K HDR. In fact clicking on the full screen button nothing happens, the Youtube 4K HDR videos are washed.
If I do the same with my Nvidia RTX2080Ti (installed on the same system) I see clearly changing the color gamma and brightness using the Youtube full screen option.

Question about your AGDCDiagnose output: is the display working properly in this mode? Does the display have DisplayPort 1.4 enabled? I assume the answer is yes to both questions since you were able to get AGDCDiagnose output and it indicates DisplayPort 1.4 versions and HBR3 link rates.

The AGDCDiagnose output shows two HBR3 connections to the LG 5K2K display. That is strange because that mode is used by the Apple Pro Display XDR display to get 6K. 5120x2160 should only require one HBR3 connection or two HBR2 connections. There's nothing wrong with having two HBR3 connections if it's sending less than 6K of pixels.

The AGDCDiagnose output shows the first connection advertises DisplayPort 1.4 and HBR3 link rate. The second connection advertises DisplayPort 1.4 and zero link rate. That's weird. Maybe the display needs to have DisplayPort 1.4 disabled for this to have non-zero link rate.

The AGDCDiagnose output shows that you are using 5120x2160 60Hz using two tiles of 2560x2160 (362 MHz pixel clock for each tile), 10 bpc, SDR (Standard Dynamic Range) mode instead of HDR (High Dynamic Range). Even though the display's second connection advertises zero link rate, it is sending two tiles at HBR3.

So it's using two tiles instead of a single tile even though it has a DisplayPort 1.4 connection. DisplayPort 1.4 needs to be enabled for HDR to work. Does HDR work with this dual tile Thunderbolt connection?

Does this mean the only way to get a single tile mode with Thunderbolt input is by using a GC-TITAN RIDGE with a single DisplayPort input connected (or PC motherboard with Thunderbolt controller and only one DisplayPort input)? Seems like it (unless you try my USB-C to DisplayPort adapter -> USB-C bidirectional cable idea).

I would like to see the AGDCDiagnose output for the HDMI input of the display ("HDMI ULTRA HD Deep Color" set to on and off), and the DisplayPort input. And with DisplayPort 1.4 enabled and disabled. I think I already have the single tile DisplayPort 1.4 EDID (product ID 0x7720 instead of 0x7721) but it won't hurt to have another.