forked from unom/punktfunk
A dmabuf import the GPU driver refuses is refused identically on every retry, but the only recovery above it was the encode-stall ladder: five in-place encoder rebuilds, then the video session ends. So a host whose driver will not take what its compositor allocates lost every session on its first frame, and every reconnect repeated it — while the very same host streamed fine with `PUNKTFUNK_ZEROCOPY=0`. The software knew how to run that machine and never chose to. Latch it, exactly as the sibling CUDA-import path already does after repeated worker deaths: three consecutive import failures with no frame in between disable the raw-dmabuf passthrough for the host process, and capture negotiates CPU frames from the next session on. Three sits below the encoder's rebuild budget, so the latch is set before the session it doomed ends — one bad session, then a working (if slower) host, with a log line saying which and why instead of an operator having to find an environment variable. Only the two stages that ARE the import are counted — the buffersrc push of the DRM-PRIME descriptor and the buffersink pull where `hwmap` maps it into a VA surface. `avcodec_send_frame` is deliberately left out: that one is the encoder stalling, which the in-place rebuild exists to recover, and taking zero-copy away permanently over a transient fault would be a bad trade. The latch lives in pf-zerocopy because it is the leaf both sides can see — the capture→encode edge is one-way by design, so pf-capture cannot ask pf-encode anything.