No 10bpc on external monitor when laptop is closed, HDR is broken

[alex133]

Hello,

I've got a Dell U3225QE 4K monitor with 10bpc matrix, connected to its built-in Thunderbolt 4 dock station with a Thunderbolt 4 (USB) cable.

My laptop is Lenovo X1 Carbon Gen 8 with integrated Intel® UHD Graphics (CML GT2) graphics.

The problem: I cannot get proper HDR output.

Observations:

- when laptop screen is closed, I cannot get 30bit on the external monitor

- when I open the 8bpc laptop screen, I immediately get 30bit on the external monitor (clearly a bug), but HDR output is still broken

- 10bpc is enabled when running live Ubuntu (X11)

- 10bpc is enabled on power-on when the monitor displays the connection information showing 30bit

- as soon as I get into my Fedora 43 with GNOME and Wayland (all latest updates), I can no longer see 10bpc, even if GNOME HDR setting is enabled, until I open laptop screen.

- HDR-enabled players display dull colors on HDR content when HDR is enabled in GNOME

- HDR-enabled browsers display jagged gradients when HDR is enabled in GNOME

I suspect there are multiple issues here, happening between the intel driver and GNOME software: unfortunate bit depth selection by the driver, and color information coordination between components.

[alex133]

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... monitor with 10bpc matrix, connected to its built-in Thunderbolt 4 dock station...

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Please read as "... monitor with 10bpc matrix, and a laptop connected to its built-in Thunderbolt 4 dock station...".

[RandyT_Intel]

Hi @alex133,

Thank you for posting in our community. I will check internally, as this may involve compatibility issues with your OEM system when using a docking station. I’ll provide an update once I gather information from OEM regarding this type of setup. We appreciate your patience while we work on this matter. Please note that this is an OEM device, so we can assist with general troubleshooting steps; however, if the issue persists, you will need to contact your device’s Original Equipment Manufacturer. OEMs often modify features, apply customizations, or make other changes to components for better compatibility with their systems.

Best regards,  

Randy T.  

Intel Customer Support Technician  

[alex133]

Hi Randy,

While I'm waiting for any discoveries from your side, let me add one more observation: gdm login screen also enables 30 bit, but the monitor switches to right 24 bit after login to GNOME.

Regards,

Alex

[RandyT_Intel]

Hi @alex133,

Based on your detailed description, you're experiencing a complex display problem that involves several components working together - your Intel graphics driver, GNOME desktop environment, and the Thunderbolt dock station. However, there's an important compatibility consideration we need to address regarding your operating system choice.

One significant factor that may be contributing to your problems is that Intel typically provides optimized graphics drivers and full feature support primarily for Ubuntu. While Fedora 43 is a excellent Linux distribution, Intel's official support and testing for advanced graphics features like HDR and 10-bit color depth is often focused on Ubuntu-based systems. This could explain why you observed that "10bpc is enabled when running live Ubuntu" but are experiencing issues with the same hardware on Fedora. Intel's graphics drivers may not be fully optimized or tested for Fedora's specific kernel versions and system configurations.

Your system hardware is definitely capable of displaying the high-quality colors you want, as proven by it working correctly with Ubuntu and on your login screen. However, the coordination problem between your Intel graphics driver and GNOME's desktop environment may be increased by running on a distribution that doesn't receive Intel's primary development focus. When you open your laptop screen and suddenly get better color depth, it suggests the drivers can work properly, but the initialization and state management may not be reliable on Fedora.

Your Thunderbolt 4 dock adds another layer of complexity to an already challenging compatibility situation. Docking stations need specific driver support to properly communicate display capabilities, and this support may be less robust on distributions outside of Intel's primary testing scope.

Given these findings, we have two main options: You can attempt troubleshooting the Fedora setup by applying different driver tweaks and system configurations; however, success may be limited due to support constraints. For further assistance, please contact the operating system vendor or the distribution maintainers. Alternatively, you might consider testing with Ubuntu (which you've already confirmed works) as your primary operating system, since Intel's graphics drivers are specifically optimized for that platform. If Ubuntu meets your other computing needs, it would likely provide the most reliable HDR and high color depth experience with your current hardware setup and try testing a direct connection between your laptop and monitor to see if the dock is the main culprit.

Should the problem persist after trying my recommended solutions, we'll need to gather some additional diagnostic information to better understand exactly what's happening with your system. This will help us provide more targeted assistance or coordinate the issue appropriately.

We'll ask you to generate an SSU (System Support Utility) log report, which captures detailed information about your hardware configuration, driver versions, system settings, and any error messages that might not be visible during normal use. This log gives us a comprehensive view of your system's state and can reveal underlying issues that aren't immediately apparent.

Additionally, we'd like you to create a screen recording that demonstrates the issue as it occurs. This should show the step-by-step process of how you reproduce the problem - for example, starting with your laptop screen closed, connecting to the external monitor, opening the laptop screen, and showing the color depth changes in your display settings. A video recording is invaluable because it allows us to observe the exact sequence of events, timing of when issues occur, and see the visual quality problems you're experiencing with HDR content. 

Best regards,  

Randy T.  

Intel Customer Support Technician  

[RandyT_Intel]

Hi @alex133,

I'm following up to see if you've had a chance to review the information I provided? Please let me know so I can determine the best next steps. 

Looking forward to your update. 

Best regards,  

Randy T.  

Intel Customer Support Technician  

[alex133]

Hello,
Thank you for your atrention.
I am away from my laptop and will only be able to provide you additional details in a week. Sorry for the delay.

Best regards,
Alex

[RandyT_Intel]

Hi @alex133,

Thank you for the update. I understand that you are currently away from your laptop and will need a week to provide the additional details we requested.

Given the timing, I will be temporarily closing this thread for now. Please note that this thread will no longer be monitored after closure. When you return and are ready to continue discussion, please submit a new thread through our community and reference this thread along with this concern for continuation. This will ensure your case receives proper attention and maintains continuity with the previous case.

Thank you for your patience, and we look forward to assisting you further when you're available.

Best regards,  

Randy T.  

Intel Customer Support Technician