Phase 0 ran the operator-mandated upstream prior-art survey FIRST,
before any source-read or hypothesis. Headline finding: the HEVC
OOPS is fundamentally re-scoped from 'kernel bug' to 'userspace UAPI
gap' against the new 7.0 controls
V4L2_CID_STATELESS_HEVC_EXT_SPS_ST_RPS / _LT_RPS.
Survey + verification:
- Casanova/Collabora v8 series merged in Linux 7.0 added the two
new V4L2 controls for VDPU381 HEVC; backend 7ac934e (June pre-iter38)
predates the UAPI and grep returns zero hits for these CIDs.
- ampere linux-api-headers is still 6.19-1, doesn't define the
constants — the backend literally cannot reference them without a
headers bump.
- ampere kernel source rkvdec-hevc-common.c:500-509 looks up the new
CIDs; if backend never set them, rkvdec_hevc_prepare_hw_st_rps
reads invalid memory via memcmp — exactly the __pi_memcmp OOPS
symptom.
VP9 still kernel-side per the v4 cover ('This patch only adds support
for H264 and H265 in both variants'). Multiple competing out-of-tree
starting trees: Sarma's android tree (working but Android-flavored),
dongioia/rock5bplus-rkvdec2 (mainline-style claims), Kwiboo (no VP9
on RK3588 yet). RKVDEC2 separate-driver path is dead — future VP9
extends the existing rkvdec driver's VDPU381 variant_ops.
Five open questions tabled for Phase 1 — most important being campaign
re-scope (HEVC moves to backend campaign; this stays VP9 kernel-only
OR becomes a meta-campaign coordinating both).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Sister to ampere-fourier (userspace consumer) and fresnel-fourier
(RK3399 peer). Tracks the 2 kernel-side blockers from ampere-fourier
iter1: HEVC OOPS in rkvdec_hevc_prepare_hw_st_rps (kernel-agent#11)
and VP9 enablement on VDPU381/383 (kernel-agent#12). AV1 stays
userspace (libva-v4l2-request-fourier#2), not in this campaign.
Process notes: Phase 0 includes a non-optional upstream prior-art
survey (linux-rockchip / linux-media / linux-mm / Kwiboo / Bootlin)
before any code; per operator policy, patches go to kernel-agent
experiment branches, NOT into the linux-ampere-fourier baseline
package.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
marfrit