Pre-iter4 backend hardcoded /dev/video0 + /dev/media0 as defaults
when no env override was set. Linux 7.0 udev/probe order changed,
rockchip-rga (RGB color converter, no codec) now claims
/dev/video0 — legacy default returns empty profile list.
Discovery is driven by the media controller graph (the canonical
v4l2-request approach). NOT a /dev/video* walk by enumeration
order — that mispairs video and media nodes when one driver
registers multiple media devices, and depends on probe-order
luck.
Algorithm:
1. Walk /dev/media0..15. MEDIA_IOC_DEVICE_INFO names the driver.
Match against {rkvdec, hantro-vpu, cedrus, sun4i_csi}.
2. MEDIA_IOC_G_TOPOLOGY enumerates the entity/interface graph.
The MEDIA_INTF_T_V4L_VIDEO interface carries major:minor of
the V4L2 video node owned by THIS media controller — paired
by the kernel, not by /dev/* enumeration order.
3. Resolve major:minor to /dev/videoN via /sys/dev/char/<M>:<N>
(the kernel's char-device sysfs symlink whose basename is
the device node name).
LIBVA_V4L2_REQUEST_NO_AUTODETECT=1 escape hatch reverts to legacy
/dev/video0 + /dev/media0 hardcoded behavior for callers that
depended on it.
Phase 5 C4 amendment: walk-and-pick-first selects rkvdec on RK3399
(rkvdec's media controller enumerates before hantro's). H.264 /
HEVC / VP9 (rkvdec codecs) work without env override after this
commit. MPEG-2 / VP8 (hantro) still require explicit
LIBVA_V4L2_REQUEST_VIDEO_PATH=/dev/video3 override; full
multi-decoder dispatch is iter4-B1 backlog item.
Verified empirically on fresnel (linux-fresnel-fourier 7.0-1):
- vainfo (no env) -> "auto-selected codec device: /dev/video1 +
/dev/media0", enumerates H264*5 + HEVCMain (rkvdec) — paired
via topology graph, not /dev/video* enumeration.
- vainfo NO_AUTODETECT=1 -> empty list (legacy /dev/video0 = rga).
- vainfo with explicit /dev/video3 + /dev/media1 -> MPEG2*2 + VP8.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Commit 3 of the upstreamable plan (upstreamable_design.md §1, §5).
Replaces the prior per-surface OUTPUT-buffer ownership model with a
small driver-wide pool sized by codec pipeline depth (4 H.264 frames
in flight), allocated unconditionally regardless of caller's
num_render_targets.
Prior art (kernel UAPI dev-stateless-decoder.rst, ffmpeg
v4l2_request.c, Chromium V4L2StatelessVideoDecoder, GStreamer
v4l2slh264dec) all decouple OUTPUT and CAPTURE pool sizing. fourier's
"output_count == surfaces_count" model was a category error: OUTPUT
buffers are request-time bitstream slots, CAPTURE buffers are
picture-time DPB slots; their lifecycles and sizing are independent.
Changes:
* NEW src/request_pool.{c,h} (~200 LoC):
- request_pool_init(): CREATE_BUFS + per-slot QUERYBUF + mmap.
- request_pool_destroy(): munmap all, idempotent.
- request_pool_acquire(): round-robin claim; returns V4L2 buffer
index of an unused slot or -1.
- request_pool_release(): mark slot free for reuse.
- request_pool_slot(): accessor for ptr/size given a buffer index.
* src/request.h: add struct request_pool output_pool to request_data.
* src/context.c::RequestCreateContext: replace the per-surface
OUTPUT loop with a single request_pool_init() call (count=4,
independent of surfaces_count). Drop the now-unused locals
(length, offset, source_data, output_buffers_count, index,
index_base, i, surface_object). DELETES patch 0002's
"output_buffers_count = ... ? ... : 4" hack inline — the pool's
own count parameter supersedes it.
* src/picture.c::RequestBeginPicture: borrow a pool slot at frame
start, write its mmap pointer/size/index into the surface's
transient source_* fields. The fields stay (still useful as
a borrow handle that the existing codec_store_buffer memcpys
target), but no longer represent surface-permanent ownership.
Reset slices_size/slices_count here too (was implicit on first
Render).
* src/surface.c::RequestSyncSurface: after VIDIOC_DQBUF returns
the OUTPUT buffer, release the pool slot and clear the surface's
borrow handle. Fixes the segv on second-frame submission.
* src/surface.c::RequestDestroySurfaces: remove the munmap of
source_data — pool owns the mmap.
* src/request.c::RequestTerminate: call request_pool_destroy()
before close(video_fd) so munmaps still target a valid fd.
* src/meson.build: add request_pool.c and request_pool.h to the
sources/headers lists.
This commit removes 0002's OUTPUT-pool hack inline (the
"floor to 4" line is gone). The DECODE_MODE/START_CODE block in 0002
remains until commit 4 lands.
Build-verified clean on aarch64.
Signed-off-by: Markus Fritsche <fritsche.markus@gmail.com>
Since our use of the v4l2 API has some assumptions on the available
userspace APIs, check the capabilities reported by the driver to make
sure they are supported.
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
This is the latest version of dma-buf export, that does support
specifying DRM modifiers.
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
This is the first version of dma-buf export, that does not support
specifying a DRM modifier.
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
claude-noether
test0r
Paul Kocialkowski