Video decoding suddenly stutters on Intel Arc A770 under Linux X11 after update

[Megadrive007]

escription:
After a system update a few days ago, videos (Chromium, MPV, VLC) using VA-API ran perfectly for 23 weeks.
Since today, videos stutter at approximately 3 FPS, even though no further updates were installed.
This occurs on X11 (Plasma Compositor OpenGL). Using Wayland wrappers provides no improvement.
Previously, everything worked flawlessly.

Steps to reproduce:

1. Start a Plasma X11 session
2. Start Chromium or MPV with GPU-decoding
3. Play a video
4. After a few hours of usage or a restart, the video stutters heavily

Expected result:
Smooth video playback with GPU acceleration

Actual result:
Videos stutter (~3 FPS), Compositor partially blocks GPU-decoding

Hardware:

• GPU: Intel Arc A770
• CPU: <AMD 5000 Series 7>
• RAM: <16 GB DDR4>

Software:

• OS: EndeavourOS
• Kernel: 6.12.64-1-lts
• Mesa/OpenGL: OpenGL version string: 4.6 (Compatibility Profile) Mesa 25.3.3-arch1.1
• Intel Media Driver (iHD): 25.3.4
• Compositor: Plasma 6.5.4, X11 OpenGL
• Session: wayland

Logs / Info:

• vainfo:
  Trying display: wayland
  vainfo: VA-API version: 1.22 (libva 2.22.0)
  vainfo: Driver version: Intel iHD driver for Intel(R) Gen Graphics - 25.3.4 ()
  vainfo: Supported profile and entrypoints
  VAProfileNone : VAEntrypointVideoProc
  VAProfileNone : VAEntrypointStats
  VAProfileMPEG2Simple : VAEntrypointVLD
  VAProfileMPEG2Main : VAEntrypointVLD
  VAProfileH264Main : VAEntrypointVLD
  VAProfileH264Main : VAEntrypointEncSliceLP
  VAProfileH264High : VAEntrypointVLD
  VAProfileH264High : VAEntrypointEncSliceLP
  VAProfileJPEGBaseline : VAEntrypointVLD
  VAProfileJPEGBaseline : VAEntrypointEncPicture
  VAProfileH264ConstrainedBaseline: VAEntrypointVLD
  VAProfileH264ConstrainedBaseline: VAEntrypointEncSliceLP
  VAProfileHEVCMain : VAEntrypointVLD
  VAProfileHEVCMain : VAEntrypointEncSliceLP
  VAProfileHEVCMain10 : VAEntrypointVLD
  VAProfileHEVCMain10 : VAEntrypointEncSliceLP
  VAProfileVP9Profile0 : VAEntrypointVLD
  VAProfileVP9Profile0 : VAEntrypointEncSliceLP
  VAProfileVP9Profile1 : VAEntrypointVLD
  VAProfileVP9Profile1 : VAEntrypointEncSliceLP
  VAProfileVP9Profile2 : VAEntrypointVLD
  VAProfileVP9Profile2 : VAEntrypointEncSliceLP
  VAProfileVP9Profile3 : VAEntrypointVLD
  VAProfileVP9Profile3 : VAEntrypointEncSliceLP
  VAProfileHEVCMain12 : VAEntrypointVLD
  VAProfileHEVCMain422_10 : VAEntrypointVLD
  VAProfileHEVCMain422_10 : VAEntrypointEncSliceLP
  VAProfileHEVCMain422_12 : VAEntrypointVLD
  VAProfileHEVCMain444 : VAEntrypointVLD
  VAProfileHEVCMain444 : VAEntrypointEncSliceLP
  VAProfileHEVCMain444_10 : VAEntrypointVLD
  VAProfileHEVCMain444_10 : VAEntrypointEncSliceLP
  VAProfileHEVCMain444_12 : VAEntrypointVLD
  VAProfileHEVCSccMain : VAEntrypointVLD
  VAProfileHEVCSccMain : VAEntrypointEncSliceLP
  VAProfileHEVCSccMain10 : VAEntrypointVLD
  VAProfileHEVCSccMain10 : VAEntrypointEncSliceLP
  VAProfileHEVCSccMain444 : VAEntrypointVLD
  VAProfileHEVCSccMain444 : VAEntrypointEncSliceLP
  VAProfileAV1Profile0 : VAEntrypointVLD
  VAProfileAV1Profile0 : VAEntrypointEncSliceLP
  VAProfileHEVCSccMain444_10 : VAEntrypointVLD
  VAProfileHEVCSccMain444_10 : VAEntrypointEncSliceLP

• lspci -k | grep -A3 -i vga:
  0b:00.0 VGA compatible controller: Intel Corporation DG2 [Arc A770] (rev 08)
  Subsystem: Shenzhen Gunnir Technology Development Co., Ltd Device 1513
  Kernel driver in use: i915
  Kernel modules: i915, xe

Additional notes:

• Issue occurs only after prolonged usage; videos are sometimes smooth immediately after a restart
• Wayland wrapper does not help

[XinfengZhang]

if possible, could you enable LIBVA_TRACE and share the trace with us?

[intel-mediadev]

Auto Created VSMGWL-82228 for further analysis.