From 91522b562665b94607337a3f30d1586f818d9387 Mon Sep 17 00:00:00 2001 From: Markus Fritsche Date: Tue, 28 Apr 2026 19:23:50 +0000 Subject: [PATCH 2/3] media: hantro: attach dma_resv release fence at buf_queue Opt the hantro driver into the new vb2 release-fence helper. When userspace QBUFs a buffer to hantro, the buffer is added to the driver's m2m queue via v4l2_m2m_buf_queue. We additionally call vb2_buffer_attach_release_fence() so each plane's dmabuf->resv gets a real producer fence attached. The fence is signalled by vb2_buffer_done when hantro completes the decode (via v4l2_m2m_buf_done_and_job_finish in hantro_drv.c, which converges on vb2_buffer_done). Wayland compositors (and any other userspace) that import hantro CAPTURE buffers and wait on the dmabuf's implicit-sync fence now wait on a real fence representing the producer's actual completion, not a stub. Validated end-to-end on PineTab2 (RK3566 / Mali-G52 / mainline 6.19 with this series backported) playing 1080p30 H.264 in chromium under stock KDE Plasma 6.6.4 Wayland: KWin's Transaction::watchDmaBuf wait completes correctly the moment hantro's IRQ fires, instead of falling back to a stub-resolved poll. Signed-off-by: Markus Fritsche --- drivers/media/platform/verisilicon/hantro_v4l2.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/media/platform/verisilicon/hantro_v4l2.c b/drivers/media/platform/verisilicon/hantro_v4l2.c index 62d3962c1..e95a3433a 100644 --- a/drivers/media/platform/verisilicon/hantro_v4l2.c +++ b/drivers/media/platform/verisilicon/hantro_v4l2.c @@ -877,6 +877,18 @@ static void hantro_buf_queue(struct vb2_buffer *vb) } v4l2_m2m_buf_queue(ctx->fh.m2m_ctx, vbuf); + + /* + * Opt in to vb2's dma_resv release-fence path. Userspace + * consumers that imported this buffer's dmabuf and wait on + * its implicit-sync fence (poll(POLLIN) or + * DMA_BUF_IOCTL_EXPORT_SYNC_FILE) get a real producer fence + * representing this device's completion, instead of the stub + * fence dma_buf_export_sync_file substitutes when dma_resv + * is empty. Best-effort: a fence-allocation failure means we + * lose implicit-sync precision, no functional regression. + */ + (void)vb2_buffer_attach_release_fence(vb); } static bool hantro_vq_is_coded(struct vb2_queue *q) -- 2.47.3