It was back in May that the surprising event happened of AMD posting HDMI 2.1 FRL patches for their open-source AMDGPU Linux driver as part of their broader HDMI 2.1 bring-up. For years the open-source HDMI 2.1 support in AMDGPU was blocked by the HDMI Forum but whether it was due to Valve or some other event, the code was finally unblocked. While it's been part of the kernel since Linux 7.2, it's been disabled by default -- except that is now changing.

Following the Fixed Rate Link (FRL) patches for higher resolutions and higher refresh rates with HDMI 2.1, patches followed for Display Stream Compression (DSC) and VRR and ALLM features important to gamers. AMD has been upstreaming these HDMI 2.1 features to the mainline Linux kernel but initially disabled by default until the Variable Refresh Rate (VRR) functionality was ready to avoid any user experience regressions.

With the functionality now in good shape, AMD is preparing to enable HDMI 2.1 FRL by default per today's patch. AMD driver engineer Fangzhi Zuo posted the patch that is inverting the logic to enable HDMI 2.1 FRL by default. Via the amdgpu.dcfeaturemask module parameter it will be possible to disable the support should it be needed for bug/regression testing or similar.

So with that, for Linux 7.4 later in the year hopefully we'll see AMDGPU VRR and ALLM ready plus now enabling FRL by default. It's too late for the current Linux 7.3 cycle but for Linux 7.4 hopefully everything will be ready. If Linux 7.3 and Linux 7.4 release on-schedule, Linux 7.4 should make it out in the last two weeks of December... In turn making it the 2026 Linux Long Term Support (LTS) kernel version and a wonderful Christmas present if HDMI 2.1 is all ready for AMD Radeon Linux users.