mpv 0.41.0's drmprime_dmabuf_importer reads correctly. Kwiboo's
ffmpeg V4L2 hwaccel at b57fbbe sets planes[1].object_index=0 for
hantro single-planar NV12 (LINEAR modifier branch, line 157), so
mpv should produce identical fd values for both .add() calls.
Runtime confirms via strace: ffmpeg does one VIDIOC_EXPBUF per
CAPTURE buffer, returning ONE fd. nb_objects=1.
The "different fds per plane" observed in WAYLAND_DEBUG is most
likely libwayland's wl_closure_marshal dup_cloexec'ing the fd at
protocol-marshal time — both .add()s use the same source fd, the
trace shows post-dup values which are consecutive but point at the
same dma_buf.
This means the earlier phase 0 conclusion ("mpv mixes per-plane
fds with single-allocation offset") was wrong. The wl_dmabuf
message is internally consistent. Bug is somewhere else.
New hypothesis space (in phase2_iter1_findings.md):
- Mali-G52 panfrost EGL_dma_buf_import with non-zero plane offset
- KWin wl_dmabuf import deduplication bug
- hantro kernel exports dma_buf with size < full allocation
- environment-reset incompleteness from earlier kwin-fourier A/B
Recommended next moves: probe fd size on ohm, mpv debug-logging
patch, KWin source-read, update issue #1 with revised analysis.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
