marfrit/libva-v4l2-request-fourier
1
0
Fork 1
Code Issues 2 Pull Requests Actions Packages Projects Releases Wiki Activity

h264: submit PRED_WEIGHTS only when WEIGHTED_PRED applies

Browse Source 
Per kernel UAPI (include/uapi/linux/v4l2-controls.h),
V4L2_CID_STATELESS_H264_PRED_WEIGHTS is a conditional control:

    V4L2_H264_CTRL_PRED_WEIGHTS_REQUIRED(pps, slice) :=
        ((pps->flags & V4L2_H264_PPS_FLAG_WEIGHTED_PRED) &&
         (slice_type == P || slice_type == SP)) ||
        (pps->weighted_bipred_idc == 1 && slice_type == B)

Submitting PRED_WEIGHTS on a frame where the macro evaluates false
triggers VIDIOC_S_EXT_CTRLS to return EINVAL at error_idx=5 (the
6th, last control in the per-request batch) on hantro-vpu and any
other driver that strictly enforces the spec.

Smoke trace from RK3568 hantro on bbb_1080p30 (Main profile, no
weighted prediction): every per-frame batch fails identically, 13
EINVALs over a 10-frame run. Without this fix, ffmpeg's vaapi-copy
falls back to software decode for every frame.

Fix: narrow num_controls to 5 (excluding PRED_WEIGHTS at index 5)
when the macro returns false; keep at 6 when it returns true.

Defect found and fixed via Phase 6 Step 1 ohm smoke testing. Not
part of Sonnet's six-commit upstreamable plan; slotted in as patch
0005 ahead of the planned probe-then-set / FRAME_BASED commits
because it unblocks per-frame submission on every backing driver,
not just hantro.

Signed-off-by: Markus Fritsche <fritsche.markus@gmail.com>
This commit is contained in:
Markus Fritsche
2026-05-01 12:00:00 +00:00
parent 565f5c0de4
commit e382c63e20
1 changed files with 17 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/h264.c
+17 -1
View File
@@ -559,8 +559,24 @@ int h264_set_controls(struct request_data *driver_data,
}
};
/*
* PRED_WEIGHTS is conditionally required per kernel UAPI:
* V4L2_H264_CTRL_PRED_WEIGHTS_REQUIRED(pps, slice) is only
* true when explicit weighted prediction applies (P/SP slice
* with WEIGHTED_PRED flag, or B slice with weighted_bipred_idc
* == 1). Submitting it unconditionally on a frame that does
* not need it triggers EINVAL at error_idx=5 on hantro and
* other drivers that strictly enforce the spec.
*
* controls[5] is PRED_WEIGHTS (last in array); narrow the
* submission count to exclude it when not required.
*/
unsigned int num_controls = 6;
if (!V4L2_H264_CTRL_PRED_WEIGHTS_REQUIRED(&pps, &slice))
num_controls = 5;
rc = v4l2_set_controls(driver_data->video_fd, surface->request_fd,
controls, 6);
controls, num_controls);
if (rc < 0)
return VA_STATUS_ERROR_OPERATION_FAILED;