Closes PW4's one remaining gap. The Steam Deck switched to Desktop Mode gives KWin on RADV, the
combination none of the earlier legs covered, and it reports no implicit fence like every other:
gamescope + NVIDIA (RTX 5070 Ti) NoFence
Mutter + NVIDIA (RTX 5070 Ti) NoFence
gamescope + RADV (Deck VANGOGH) 300/300 NoFence, mean 23us, p99 <=100us
KWin + RADV (Deck desktop) no fence (older build's wording: waited=false)
That is every compositor x vendor this fleet has. PW4 retires with no outstanding doubt rather
than "probably fine except one box we never tried".
Measured with the Deck's OWN already-authorized binary rather than a scratch build, because KWin
grants zkde_screencast_unstable_v1 per EXECUTABLE PATH: it resolves /proc/<pid>/exe against a
.desktop's Exec= and caches the grant on first connect, so an unregistered path is refused outright
and registering one needs a re-login. The fence probe is pre-existing capture-path code, so a build
from July answers the outcome question perfectly well — and nothing of the user's was modified to
get it.
Comment-only; no behaviour change. fmt + pf-capture clippy -D warnings green.
enricobuehler
4f5ca5f9bc