From 4fb4bf2f8e88973a4b575b537c774dd563160c5f Mon Sep 17 00:00:00 2001 From: Dave Stevenson Date: Mon, 28 Mar 2022 11:52:48 +0100 Subject: [PATCH] bcm2835-codec: Return empty buffers to the VPU instead of queueing to vbuf2 The encoder can skip frames totally should rate control overshoot the target bitrate too far. In this situation it generates an output buffer of length 0. V4L2 treats a buffer of length 0 as an end of stream flag, which is not appropriate in this case, therefore we can not return that buffer to the client. The driver was returning the buffer to videobuf2 in the QUEUED state, however that buffer was then not dequeued again, so the number of buffers was reduced each time this happened. In the pathological case of using GStreamer's videotestsrc in mode 1 for noise, this happens sufficiently frequently to totally stall the pipeline. If the port is still enabled then return the buffer straight back to the VPU rather than to videobuf2. Signed-off-by: Dave Stevenson --- .../bcm2835-codec/bcm2835-v4l2-codec.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) --- a/drivers/staging/vc04_services/bcm2835-codec/bcm2835-v4l2-codec.c +++ b/drivers/staging/vc04_services/bcm2835-codec/bcm2835-v4l2-codec.c @@ -1159,10 +1159,15 @@ static void op_buffer_cb(struct vchiq_mm v4l2_dbg(2, debug, &ctx->dev->v4l2_dev, "%s: Empty buffer - flags %04x", __func__, mmal_buf->mmal_flags); if (!(mmal_buf->mmal_flags & MMAL_BUFFER_HEADER_FLAG_EOS)) { - vb2_buffer_done(&vb2->vb2_buf, VB2_BUF_STATE_QUEUED); - if (!port->enabled && - atomic_read(&port->buffers_with_vpu)) - complete(&ctx->frame_cmplt); + if (!port->enabled) { + vb2_buffer_done(&vb2->vb2_buf, VB2_BUF_STATE_QUEUED); + if (atomic_read(&port->buffers_with_vpu)) + complete(&ctx->frame_cmplt); + } else { + vchiq_mmal_submit_buffer(ctx->dev->instance, + &ctx->component->output[0], + mmal_buf); + } return; } }