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Disabling HDCP / Huion Kamvas 16 Pro

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I recently bought a Huion Kamvas 16 (2021) drawing tablet. I have a dual monitor setup, with a DELL U2515H 1440p and an LG 27UL600 4K.

When I connect the device to my Vega 56 using HDMI, the screen displays the content correctly for about 5 seconds, but then turns to static.
The tablet registers pencil input just fine. The HDMI port works fine, as I tested it with a monitor I had laying around.

I had the same problem booting in Windows, but was able to resolve the issue by disabling DHCP HDCP for the device in Radeon settings.
That's why I assume that DHCP HDCP is the culprit. I am NOT well versed in this subject.

When I boot my Hack in safe mode, this issue does not occur (though my LG display does not output anything).

I have just updated macOS to the latest version (11.2.3), that did not resolve the issue.
I read something about using a cheap Chinese DP to HDMI converter, as that would bypass the DHCP. Surely there must be a more elegant solution?

Any help would be very welcome.
 

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Edhawk

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This is the link/information I found for your tablet - https://store.huion.com/products/kamvas-16-2021

So I am assuming you have the Tablet setup as follows:
  1. you have a USB connection from the Huion Kamvas 16 (2021) drawing tablet to a USB port on your rear I/O or case.
  2. You have a second USB connection from the tablet to the HDMI port on your RX Vega 56. I assume you are using the 3-in-1 cable (USB to HDMI/Type-C/DP) for the Huion tablet connection to the dGPU.
Which Display are you mirroring/projecting to the tablet the LG 4K or Dell 1440P?

Not sure I understand where the DHCP issue comes in to this setup. As you are not using an IP address to connect the Tablet to the graphics card or one of the displays.

Have you tried using the third DP port on the RX Vega 56 in place of the HDMI port? Or switching the LG to the HDMI port and the Tablet to the DP port the LG display is currently using?
 
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This is the link/information I found for your tablet - https://store.huion.com/products/kamvas-16-2021

So I am assuming you have the Tablet setup as follows:
  1. you have a USB connection from the Huion Kamvas 16 (2021) drawing tablet to a USB port on your rear I/O or case.
  2. You have a second USB connection from the tablet to the HDMI port on your RX Vega 56. I assume you are using the 3-in-1 cable (USB to HDMI/Type-C/DP) for the Huion tablet connection to the dGPU.
Correct. Thank you for making time.

Here's a video showing the bug using that setup:

Which Display are you mirroring/projecting to the tablet the LG 4K or Dell 1440P?
None. Ideally, I want to use it as an extended desktop. Whichever monitor I mirror (also when mirroring all monitors), the tablet works for 5 seconds, and then goes back to noise.

Not sure I understand where the DHCP issue comes in to this setup. As you are not using an IP address to connect the Tablet to the graphics card or one of the displays.
I am NOT well-versed on this subject. The same issue occurred when booting Windows, but I was able to solve the problem there, thanks to this thread on the AMD forum. Hence the hunch.
I also have no idea why the tablet does work in Safe Mode.

Have you tried using the third DP port on the RX Vega 56 in place of the HDMI port? Or switching the LG to the HDMI port and the Tablet to the DP port the LG display is currently using?
I have not. I'll order a DP to HDMI converter now, as well as a DP splitter ($$$), just to be sure.

Edit: I went to a friend and connected the tablet to his MacBook Pro. No issues there whatsoever.
 
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Edhawk

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The link refers to HDCP not DHCP, I can see why you made this mistake but these are two completely different protocols.

HDCP - High-bandwidth Digital Content Protection, is a form of digital copy protection developed by Intel Corporation to prevent copying of digital audio and video content as it travels across connections. Types of connections include DisplayPort (DP), Digital Visual Interface (DVI), and High-Definition Multimedia Interface (HDMI). (Extract from Wikipedia HDCP post).

As far as I am aware there is no way to disable HDCP on a Mac. As you do not have the same level of access to the drivers for the Discrete GPU, as you do in Windows.

What happens if you connect just one screen and the tablet, does the tablet work alongside the screen?

Not sure if this will be helpful, but do you have the shikigva=80 boot argument in your config.plist. This boot argument works with iMac and Mac-Mini systems that use the Intel iGPU and an AMD dGPU to enable Digital Rights Management (DRM) playback on Hacks. Adding this boot argument to your config.plist may enable your tablet to work, if the HDCP/DRM protocol is preventing your Tablet from working correctly. It may not make any difference but we won't know until you try adding it.
 
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The link refers to HDCP not DHCP, I can see why you made this mistake but these are two completely different protocols.
I see, my mistake. Updated thread title accordingly.

What happens if you connect just one screen and the tablet, does the tablet work alongside the screen?
It does not, in any configuration.

Not sure if this will be helpful, but do you have the shikigva=80 boot argument in your config.plist. This boot argument works with iMac and Mac-Mini systems that use the Intel iGPU and an AMD dGPU to enable Digital Rights Management (DRM) playback on Hacks. Adding this boot argument to your config.plist may enable your tablet to work, if the HDCP/DRM protocol is preventing your Tablet from working correctly. It may not make any difference but we won't know until you try adding it.
This is well above my pay grade, so thank you for your patience.

According to this chart I'd need to use shikigva=128 (I think), since I'm running an iMac Pro (and not an MP or MM). I tested my DRM following this guide, and ran into QuickTime crashes opening FairPlay 1.x. Other FairPlays work without any issues. This might also explain another bug I sporadically encounter, where Safari seems to unstoppably fast-forward media playback.

Now I can't figure out which one is my dGPU PciRoot path. If you could point it out for me, I would very much appreciate it. If not, I'll have my developer friend look at next week.
 

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Feartech

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I see, my mistake. Updated thread title accordingly.


It does not, in any configuration.


This is well above my pay grade, so thank you for your patience.

According to this chart I'd need to use shikigva=128 (I think), since I'm running an iMac Pro (and not an MP or MM). I tested my DRM following this guide, and ran into QuickTime crashes opening FairPlay 1.x. Other FairPlays work without any issues. This might also explain another bug I sporadically encounter, where Safari seems to unstoppably fast-forward media playback.

Now I can't figure out which one is my dGPU PciRoot path. If you could point it out for me, I would very much appreciate it. If not, I'll have my developer friend look at next week.
normally it is PciRoot(0x0)/Pci(0x2,0x0)
 
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PCI(0x2, 0x0) is IGPU address
normally it is PciRoot(0x0)/Pci(0x2,0x0)

I don't see that on the list. Is it possible that I need to add it manually? Just click the plus and type PciRoot(0x0)/Pci(0x2,0x0) ? Again, I'm a noob, thank you for your help.
Also, I thought the problem was with the dGPU, not the iGPU?
 

Edhawk

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If you are using the iMac Pro SMBIOS, have you disabled your IGPU in your Bios? As a real iMac Pro doesn't have an IGPU, with a Xeon CPU it only has the discrete Graphics card.

If you have the IGPU active in macOS with the iMac Pro setup that might be part of the reason for your graphics issues.

Why aren't you using the iMac 19,1 SMBIOS, which is a better match to your setup?
 
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