HDMI VRR not detected on Steam Machine with Hisense 43E78QTUK

Steam Machine: HDMI VRR advertised by TV EDID but amdgpu reports vrr_capable=0

Description

SteamOS 3.8.25 does not expose VRR when my Steam Machine is connected directly via HDMI to a Hisense 43E78QTUK TV.

The TV explicitly advertises HDMI Forum VRR support in its EDID, with a supported VRR range of 48–60 Hz, but the AMDGPU DRM driver reports the HDMI connector as not VRR capable. Consequently, KScreen reports Vrr: incapable and VRR cannot be enabled in SteamOS/Gamescope.

Hardware/software

• Device: Steam Machine
• SteamOS: 3.8.25
• Kernel: 6.18.42-valve2-1-neptune-618-gaf6356cf2488
• GPU: AMD Radeon, PCI ID 1002:7481
• Driver: amdgpu 3.64.0
• Display Core: v3.2.351
• Display: Hisense 43E78QTUK
• Connection: direct HDMI connection, no dock, receiver, switch, or adapter
• DRM connector: HDMI-A-1

TV EDID

The TV's EDID is correctly detected by Linux. edid-decode reports the following HDMI Forum Vendor-Specific Data Block:

Vendor-Specific Data Block (HDMI Forum), OUI C4-5D-D8:
  Version: 1
  Maximum TMDS Character Rate: 600 MHz
  SCDC Present
  Supports UHD VIC
  Supports 16-bits/component Deep Color 4:2:0 Pixel Encoding
  Supports 12-bits/component Deep Color 4:2:0 Pixel Encoding
  Supports 10-bits/component Deep Color 4:2:0 Pixel Encoding
  Supports media rates below VRRmin (CinemaVRR, deprecated)
  Supports Auto Low-Latency Mode
  VRRmin: 48 Hz
  VRRmax: 60 Hz

Therefore the sink is explicitly advertising HDMI Forum VRR capability from 48 to 60 Hz.

The EDID is read successfully from:

/sys/class/drm/card0-HDMI-A-1/edid

DRM/AMDGPU result

modetest -M amdgpu -c detects HDMI-A-1 as connected and exposes the expected display modes, including 3840×2160@60 and 1920×1080@120.

However, the connector property is:

HDMI-A-1:
  vrr_capable:
    flags: immutable range
    values: 0 1
    value: 0

The same vrr_capable=0 result is present when testing the 1920×1080@120 mode.

KScreen consequently reports:

Vrr: incapable

Reproduction

1. Boot SteamOS 3.8.25.
2. Connect the Steam Machine directly to the Hisense 43E78QTUK via HDMI.
3. Enter Desktop Mode.
4. Run:

kscreen-doctor -o

The display reports Vrr: incapable.

5. Run:

modetest -M amdgpu -c

HDMI-A-1 reports:

vrr_capable = 0

6. Decode the EDID:

edid-decode /sys/class/drm/card0-HDMI-A-1/edid

The EDID reports:

VRRmin: 48 Hz
VRRmax: 60 Hz

Expected behaviour

Because the HDMI sink advertises HDMI Forum VRR support from 48–60 Hz, AMDGPU should expose the connector as VRR capable (vrr_capable=1), allowing SteamOS/Gamescope to use VRR within that range.

Actual behaviour

Despite the EDID explicitly advertising HDMI Forum VRR, AMDGPU reports:

vrr_capable = 0

VRR is therefore unavailable to KScreen/Gamescope/Steam.

Additional information

The system is using:

amdgpu.dcdebugmask=0x20000

in the kernel command line.

The relevant kernel initialization messages show Display Core initializing successfully:

amdgpu: [drm] Display Core v3.2.351 initialized on DCN 3.2.1
amdgpu: [drm] DP-HDMI FRL PCON supported
amdgpu: [drm] HDMI-A-1: PSR support 0, DC PSR ver -1, sink PSR ver 0 DPCD caps 0x0

There are no obvious HDMI or VRR error messages in the kernel log.

A SteamOS system report is attached/provided separately.

Steam ID is 76561198083691854

This appears to be an AMDGPU/Display Core VRR capability-detection issue: the HDMI Forum VRR capability is present in the sink EDID, but the DRM connector is nevertheless exposed with vrr_capable=0.

systemreport-20260823144102.txt

Start by reproducing the report with kscreen-doctor -o, modetest -M amdgpu -c, and edid-decode on /sys/class/drm/card0-HDMI-A-1/edid. Compare the HDMI Forum VRR data with the amdgpu Display Core result for vrr_capable. Done means the connector correctly reports VRR capability for the advertised 48–60 Hz range and KScreen/Gamescope can use it.