Valve confirmed this week that the HDMI Forum continues to block HDMI 2.1 features from Linux open-source drivers, directly impacting the new Steam Machine despite its hardware being fully HDMI 2.1-capable. The company told Ars Technica that HDMI 2.1 support is “still a work-in-progress on the software side” and they’ve “been working on trying to unblock things there.” The Steam Machine—launching early 2026 with AMD’s powerful Zen 4 CPU and RDNA 3 GPU—must officially list HDMI 2.0 support despite having HDMI 2.1 hardware.
This isn’t just about one gaming device. It’s a licensing battle affecting millions of Linux gamers, desktop users with AMD GPUs, and anyone developing for open-source platforms. They cannot access modern HDMI features like native 4K@120Hz, VRR (Variable Refresh Rate), or dynamic HDR via HDMI connections while Windows users on identical hardware can.
Why HDMI 2.1 Can’t Work on Linux
The HDMI Forum refuses to allow open-source implementations of HDMI 2.1 because publishing GPL-licensed code would indirectly expose their proprietary specification to the public. In 2021, the HDMI Forum closed public access to specifications, limiting them to paying “HDMI Adopters.” Since Linux kernel drivers must be open-source (GPL-licensed), implementing HDMI 2.1 would violate HDMI’s licensing terms by “leaking information” about the proprietary spec.
AMD spent months in early 2024 engineering HDMI 2.1 support for their open-source AMDGPU kernel driver and submitted it to the HDMI Forum for approval. The HDMI Forum rejected it outright. AMD confirmed the effort “concluded and failed,” leaving bug reports for 4K@120Hz and 5K@240Hz support via HDMI on Linux open for over three years.
This isn’t a technical problem—it’s a fundamental incompatibility between closed specifications and open-source transparency. Even major manufacturers like AMD with HDMI Forum membership cannot bridge this gap.
The Features Linux Users Can’t Access
HDMI 2.1 offers 48Gbps bandwidth (versus HDMI 2.0’s 18Gbps), enabling true 4K@120Hz without compression, plus Variable Refresh Rate (VRR), Auto Low Latency Mode (ALLM), dynamic HDR, and enhanced audio. Linux users stuck on HDMI 2.0 miss all these features when using HDMI connections.
The Steam Machine can achieve 4K@120Hz only by using chroma subsampling—a compression technique that noticeably degrades quality, especially for text. Valve validated the Steam Machine’s HDMI 2.1 hardware under Windows to confirm it works correctly, proving the limitation is purely software and licensing-based, not technical.
Meanwhile, the DisplayPort 1.4 output on the same device works perfectly with 4K@240Hz, VRR, and all modern features. The hardware is identical. The difference? DisplayPort has an open, royalty-free specification.
DisplayPort: The Open Alternative That Actually Works
DisplayPort is royalty-free, has an open specification, and works perfectly with Linux open-source drivers. The Steam Machine’s DisplayPort 1.4 output supports 4K@240Hz, 8K@60Hz, VRR/FreeSync, and full HDR—everything HDMI 2.1 should offer but doesn’t on Linux.
AMD’s FreeSync works perfectly via DisplayPort on Linux but not via HDMI because of the same licensing restrictions. The Hacker News discussion on Valve’s announcement (298 points, 182 comments) shows community consensus: “open-source Linux advocates should try to use DisplayPort instead if at all possible.”
Related: Linux Kernel Rust Experiment Over: Real Fight Begins
PC gaming monitors are increasingly prioritizing DisplayPort over HDMI. It’s objectively better for open-source ecosystems, and manufacturers are responding to that reality.
AMD Tried and Failed in 2024
AMD’s rejection in March 2024 proved HDMI 2.1 likely won’t come to Linux. AMD engineers spent months prototyping code, submitted it to HDMI Forum, and were rejected. This wasn’t a small effort—it was a major engineering initiative from one of the largest GPU manufacturers and an HDMI Forum member.
According to The Register, AMD had validated HDMI 2.1 features internally in their AMDGPU codebase and formally submitted it to HDMI Forum for review. The rejection was final. No negotiations, no compromise. Bug reports dating back three years for 4K@120Hz support remain unresolved.
Valve’s current “trying to unblock” effort faces the same wall AMD hit. Technical prowess doesn’t matter when the blocker is licensing policy, not code.
What This Means for Linux Gaming
The HDMI Forum’s stance may backfire long-term. Linux gaming is growing—Steam Deck sold millions, Steam Machine launches in 2026—and manufacturers are responding by prioritizing DisplayPort. USB-C with DisplayPort Alt Mode is becoming standard, further marginalizing HDMI in the PC space.
The Steam Machine ships with both DisplayPort 1.4 (full-featured) and HDMI (limited to 2.0). Valve’s documentation explicitly notes the HDMI limitation and recommends DisplayPort for best performance. Industry trend: PC gaming monitors increasingly ship with DisplayPort as primary, HDMI as secondary.
HDMI Forum’s proprietary control may cost them the growing Linux gaming market. DisplayPort is positioned to become the standard for PC gaming, relegating HDMI to consumer electronics like TVs and consoles where Linux presence is minimal.
Key Takeaways
- HDMI 2.1 is blocked on Linux due to GPL licensing incompatibility with HDMI Forum’s closed specification—AMD’s 2024 attempt to implement it was rejected outright
- Linux gamers miss native 4K@120Hz, VRR, ALLM, and dynamic HDR via HDMI while Windows users on identical hardware get full access
- DisplayPort works perfectly on Linux with all modern features (4K@240Hz, VRR, HDR) because it’s royalty-free and open-source friendly
- Valve’s Steam Machine has HDMI 2.1 hardware validated on Windows but must list HDMI 2.0 support on Linux—the limitation is licensing, not technical
- For Linux users: prioritize DisplayPort when buying monitors and cables—HDMI 2.1 support isn’t coming unless HDMI Forum changes policy
Valve’s public criticism signals growing frustration with proprietary standards blocking open-source innovation. The smart money is on DisplayPort for Linux gaming going forward.
