AMD has sent support to DRM-Next initial support for HDMI 2.1 Fixed Rate Link (FRL) for the open driver AMDGPU. The change is being prepared for inclusion in the merge window Linux 7.2, which is set to open in June. This is a significant event for Radeon users on Linux: the lack of FRL has long hindered the full functionality of modes like 4K with high refresh rates over HDMI on the open driver.
FRL is a data transmission mechanism for HDMI 2.1, replacing the limitations of the old TMDS approach of HDMI 2.0. It is necessary for higher bandwidth: modern TVs, 4K/120 Hz, 5K/240 Hz, and other modes where DisplayPort has usually coped, while HDMI on AMDGPU in Linux has faced limitations.
History has been in development for several years. Previously, AMD had working code but could not properly publish the HDMI 2.1 implementation in the open driver due to HDMI Forum requirements. In February 2024, AMD engineer Alex Deitcher stated that an open implementation of HDMI 2.1 is not possible without violating HDMI Forum requirements. Now the situation has changed: AMD has begun to publish patches for FRL, DSC, and related changes for AMDGPU.
Currently, the implementation of support does not mean that "HDMI 2.1 is fully operational on Linux", but it is the first real step towards it in the main kernel. If the patches pass review in DRM-Next, Radeon users will gain the foundation for the full functionality of modern HDMI displays without a closed driver and without workarounds.
Source: linux.org.ru
