VA-API not working, no hardware H.264 decoding with UVD on ThinLinc

ThinLinc
1

Hi,

I’m trying to enable hardware-accelerated H.264 decoding (UVD) using VA-API on a ThinLinc setup, but so far, VA-API fails to initialize, and decoding falls back to software (llvmpipe). I’m not sure what’s causing the issue and would appreciate help diagnosing it.

Environment:

  • ThinLinc client: 4.19.0-4005
  • ThinLinc server: 4.19.0-4116
  • OS: Linux Mint 21.3 (based on Ubuntu 22.04, kernel 5.15)
  • GPU: AMD GX-415GA SOC with Radeon HD Graphics
  • User is in video and render groups
  • VA-API version: 1.14.0
  • /dev/dri/ contains card0 and renderD128

Symptoms:

vainfo output:

libva info: VA-API version 1.14.0
libva error: vaGetDriverNameByIndex() failed with unknown libva error, driver_name = (null)
vaInitialize failed with error code -1 (unknown libva error)

glxinfo shows software rendering:

OpenGL renderer string: llvmpipe (LLVM 15.0.7, 256 bits)

dmesg confirms amdgpu loads and UVD is initialized:

[drm] add ip block number 7 <uvd_v4_2>
...
[drm] Found UVD firmware Version: 1.64 Family ID: 9
[drm] UVD initialized successfully.

What I’ve checked so far:

  • amdgpu module is loaded
  • User has access to /dev/dri/* devices
  • DRM and firmware initialization succeeds
  • Tried running vainfo from both the ThinLinc session and a regular X session (same result)

Questions:

  1. Does ThinLinc do anything special with VA-API or GPU access that might interfere?
  2. Is there a known issue with VA-API and amdgpu on Kabini APUs in ThinLinc environments?
  3. Should I manually set LIBVA_DRIVER_NAME=radeonsi? If so, where should this be exported in a ThinLinc session?

Thanks in advance for any hints or suggestions!

—
Krzysztof

2

Hi @kszwaba,

Thanks for the detailed report!

The X server responsible for your ThinLinc session generally won’t have access to the GPU, even if the user has the correct permissions. So for example, if you want to run accelerated OpenGL applications in a ThinLinc session, you’d need to use something like VirtualGL. This is why glxinfo is showing a fallback to software rendering.

ThinLinc shouldn’t affect things outside of a ThinLinc session, though. So if you’re unable to get sensible output from vainfo at the local console for example, then you would need to resolve this first.

I’m not familiar with VA-API at all, so the following is pure guesswork :slight_smile: but if/when you have vainfo working at the local console, you might like to try unsetting the DISPLAY environment variable before running vainfo within the ThinLinc session. This will (hopefully) prevent it from trying to use ThinLinc’s X server for GPU access, and get it to use the console one instead. So something like:

DISPLAY= vainfo

or

DISPLAY=:0.0 vainfo

Note that you shouldn’t change the DISPLAY variable globally, for example by exporting it, since ThinLinc relies on this being set correctly.

Let us know how you get on.