I patched kernel 7.3-rc1, and I have KDE's Adaptive Sync property set to
Automatic (Always makes the display gamma flicker). VRR itself is only
engaged when entering a game.
My display (an LG C1 connected through an Onkyo RZ70 AVR) shows "fixed"
when VRR is not active. While this seems logical, it causes the display
to go blank every time I enter or exit a game, or, even worse, when I
alt-tab while in a game.
In my case, I can have periods of up to 10 seconds with no image while
the devices in the HDMI chain disagree with each other, and sometimes I
lose the image completely.
A kernel parameter to force VRR to always be enabled should be
available. This would prevent these signal-switching problems, and it is
how "FreeSync" actually works and also with the unofficial kernel
patches for AMD HDMI 2.1 + VRR on kernel 7.2.
There is also some evidence that keeping VRR active can avoid the
mode-switch behavior seen on some TVs when VRR is enabled or disabled.
On 14/08/2026 17:43, Fangzhi Zuo wrote:
This series adds HDMI 2.1 gaming support to amdgpu: Variable Refresh Rate
(VRR) derived from the HDMI Forum VSDB (HF-VSDB), and Auto Low-Latency
Mode (ALLM). It builds on a drm/edid patch that parses the HF-VSDB gaming
capabilities into struct drm_hdmi_info.
- Patch 1 reports FreeSync from the AMD VSDB (existing mechanism).
- Patch 2 (drm/edid) parses the HF-VSDB VRR range and ALLM bit.
- Patch 3 enables VRR from the HF-VSDB when the AMD VSDB has no range.
- Patch 4 signals ALLM_Mode in the HF-VSIF when Gaming-VRR is active.
v1: https://lore.kernel.org/amd-gfx/[email protected]/
v2: https://lore.kernel.org/amd-gfx/[email protected]/
v3: https://lore.kernel.org/amd-gfx/[email protected]/
Changes since v3:
- Drop the content-type based ALLM heuristic. ALLM_Mode is now set only
for the mandatory Gaming-VRR case (VRR_EN=1 with a sink that advertises
ALLM), per HDMI 2.1 Section 7.6.6; it is no longer derived from the
content type.
Changes since v2:
- Fix coding-style issues in the VTEM info-packet code.
Fangzhi Zuo (3):
drm/amd/display: Add 2.1 FreeSync support for AMD VSDB EDID Block
drm/amd/display: Add HDMI 2.1 VRR support from HF-VSDB
drm/amd/display: Enable HDMI ALLM for Gaming-VRR
Tomasz PakuĊa (1):
drm/edid: parse HDMI 2.1 gaming (ALLM/VRR) capabilities from HF-VSDB
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 5 +-
.../display/amdgpu_dm/amdgpu_dm_connector.c | 71 +++++++++++-
.../display/amdgpu_dm/amdgpu_dm_freesync.c | 41 +++++++
.../amd/display/modules/inc/mod_info_packet.h | 4 +
.../display/modules/info_packet/info_packet.c | 109 ++++++++++++++++++
drivers/gpu/drm/drm_edid.c | 42 +++++++
include/drm/drm_connector.h | 47 ++++++++
7 files changed, 317 insertions(+), 2 deletions(-)
base-commit: de2622bbc20276eaaaafa8fdbd374ace1ced28dc
