Re: [PATCH v3 05/15] media: mtk-vcodec: vdec: support stateless API

[Alexandre Courbot]

Hi Ezequiel, thanks for the feedback!

On Thu, Mar 4, 2021 at 6:30 AM Ezequiel Garcia
<ezequiel@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello Alex,
>
> Thanks for the patch.
>
> On Fri, 26 Feb 2021 at 07:06, Alexandre Courbot <acourbot@xxxxxxxxxxxx> wrote:
> >
> > From: Yunfei Dong <yunfei.dong@xxxxxxxxxxxx>
> >
> > Support the stateless codec API that will be used by MT8183.
> >
> > Signed-off-by: Yunfei Dong <yunfei.dong@xxxxxxxxxxxx>
> > [acourbot: refactor, cleanup and split]
> > Co-developed-by: Alexandre Courbot <acourbot@xxxxxxxxxxxx>
> > Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxxxx>
> > ---
> >  drivers/media/platform/mtk-vcodec/Makefile    |   1 +
> >  .../platform/mtk-vcodec/mtk_vcodec_dec.c      |  66 ++-
> >  .../platform/mtk-vcodec/mtk_vcodec_dec.h      |   9 +-
> >  .../mtk-vcodec/mtk_vcodec_dec_stateless.c     | 427 ++++++++++++++++++
> >  .../platform/mtk-vcodec/mtk_vcodec_drv.h      |   3 +
> >  5 files changed, 503 insertions(+), 3 deletions(-)
> >  create mode 100644 drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_stateless.c
> >
> [..]
>
> > +
> > +static const struct mtk_stateless_control mtk_stateless_controls[] = {
> > +       {
> > +               .cfg = {
> > +                       .id = V4L2_CID_STATELESS_H264_SPS,
> > +               },
> > +               .codec_type = V4L2_PIX_FMT_H264_SLICE,
> > +               .needed_in_request = true,
>
> This "needed_in_request" is not really required, as controls
> are not volatile, and their value is stored per-context (per-fd).
>
> It's perfectly valid for an application to pass the SPS control
> at the beginning of the sequence, and then omit it
> in further requests.

If I understand how v4l2_ctrl_request_hdl_ctrl_find() works with
requests, this boolean only checks that the control has been provided
at least once, and not that it is provided with every request. Without
it we could send a frame to the firmware without e.g. setting an SPS,
which would be a problem.

>
> > +       },
> > +       {
> > +               .cfg = {
> > +                       .id = V4L2_CID_STATELESS_H264_PPS,
> > +               },
> > +               .codec_type = V4L2_PIX_FMT_H264_SLICE,
> > +               .needed_in_request = true,
> > +       },
> > +       {
> > +               .cfg = {
> > +                       .id = V4L2_CID_STATELESS_H264_SCALING_MATRIX,
> > +               },
> > +               .codec_type = V4L2_PIX_FMT_H264_SLICE,
> > +               .needed_in_request = true,
> > +       },
> > +       {
> > +               .cfg = {
> > +                       .id = V4L2_CID_STATELESS_H264_DECODE_PARAMS,
> > +               },
> > +               .codec_type = V4L2_PIX_FMT_H264_SLICE,
> > +               .needed_in_request = true,
> > +       },
> > +       {
> > +               .cfg = {
> > +                       .id = V4L2_CID_MPEG_VIDEO_H264_PROFILE,
> > +                       .def = V4L2_MPEG_VIDEO_H264_PROFILE_MAIN,
> > +                       .max = V4L2_MPEG_VIDEO_H264_PROFILE_HIGH,
> > +                       .menu_skip_mask =
> > +                               BIT(V4L2_MPEG_VIDEO_H264_PROFILE_BASELINE) |
> > +                               BIT(V4L2_MPEG_VIDEO_H264_PROFILE_EXTENDED),
> > +               },
> > +               .codec_type = V4L2_PIX_FMT_H264_SLICE,
> > +       },
> > +       {
> > +               .cfg = {
> > +                       .id = V4L2_CID_STATELESS_H264_DECODE_MODE,
> > +                       .min = V4L2_STATELESS_H264_DECODE_MODE_FRAME_BASED,
> > +                       .def = V4L2_STATELESS_H264_DECODE_MODE_FRAME_BASED,
> > +                       .max = V4L2_STATELESS_H264_DECODE_MODE_FRAME_BASED,
> > +               },
> > +               .codec_type = V4L2_PIX_FMT_H264_SLICE,
> > +       },
> > +};
>
> Applications also need to know which V4L2_CID_STATELESS_H264_START_CODE
> the driver supports. From a next patch, this case seems to be
> V4L2_STATELESS_H264_START_CODE_ANNEX_B.

Indeed - I've added the control, thanks for catching this!

>
> > +#define NUM_CTRLS ARRAY_SIZE(mtk_stateless_controls)
> > +
> > +static const struct mtk_video_fmt mtk_video_formats[] = {
> > +       {
> > +               .fourcc = V4L2_PIX_FMT_H264_SLICE,
> > +               .type = MTK_FMT_DEC,
> > +               .num_planes = 1,
> > +       },
> > +       {
> > +               .fourcc = V4L2_PIX_FMT_MM21,
> > +               .type = MTK_FMT_FRAME,
> > +               .num_planes = 2,
> > +       },
> > +};
> > +#define NUM_FORMATS ARRAY_SIZE(mtk_video_formats)
> > +#define DEFAULT_OUT_FMT_IDX    0
> > +#define DEFAULT_CAP_FMT_IDX    1
> > +
> > +static const struct mtk_codec_framesizes mtk_vdec_framesizes[] = {
> > +       {
> > +               .fourcc = V4L2_PIX_FMT_H264_SLICE,
> > +               .stepwise = {
> > +                       MTK_VDEC_MIN_W, MTK_VDEC_MAX_W, 16,
> > +                       MTK_VDEC_MIN_H, MTK_VDEC_MAX_H, 16,
> > +               },
> > +       },
> > +};
> > +
> > +#define NUM_SUPPORTED_FRAMESIZE ARRAY_SIZE(mtk_vdec_framesizes)
> > +
> > +static void mtk_vdec_stateless_set_dst_payload(struct mtk_vcodec_ctx *ctx,
> > +                                              struct vdec_fb *fb)
> > +{
> > +       struct mtk_video_dec_buf *vdec_frame_buf =
> > +               container_of(fb, struct mtk_video_dec_buf, frame_buffer);
> > +       struct vb2_v4l2_buffer *vb = &vdec_frame_buf->m2m_buf.vb;
> > +       unsigned int cap_y_size = ctx->q_data[MTK_Q_DATA_DST].sizeimage[0];
> > +
> > +       vb2_set_plane_payload(&vb->vb2_buf, 0, cap_y_size);
> > +       if (ctx->q_data[MTK_Q_DATA_DST].fmt->num_planes == 2) {
> > +               unsigned int cap_c_size =
> > +                       ctx->q_data[MTK_Q_DATA_DST].sizeimage[1];
> > +
> > +               vb2_set_plane_payload(&vb->vb2_buf, 1, cap_c_size);
> > +       }
> > +}
> > +
> > +static struct vdec_fb *vdec_get_cap_buffer(struct mtk_vcodec_ctx *ctx,
> > +                                          struct vb2_v4l2_buffer *vb2_v4l2)
> > +{
> > +       struct mtk_video_dec_buf *framebuf =
> > +               container_of(vb2_v4l2, struct mtk_video_dec_buf, m2m_buf.vb);
> > +       struct vdec_fb *pfb = &framebuf->frame_buffer;
> > +       struct vb2_buffer *dst_buf = &vb2_v4l2->vb2_buf;
> > +
> > +       pfb = &framebuf->frame_buffer;
> > +       pfb->base_y.va = vb2_plane_vaddr(dst_buf, 0);
>
> Are you sure you need a CPU mapping? It seems strange.
> I'll comment some more on the next patch(es).

I'll answer on the next patch since this is where that mapping is being used.

>
> > +       pfb->base_y.dma_addr = vb2_dma_contig_plane_dma_addr(dst_buf, 0);
> > +       pfb->base_y.size = ctx->q_data[MTK_Q_DATA_DST].sizeimage[0];
> > +
> > +       if (ctx->q_data[MTK_Q_DATA_DST].fmt->num_planes == 2) {
> > +               pfb->base_c.va = vb2_plane_vaddr(dst_buf, 1);
> > +               pfb->base_c.dma_addr =
> > +                       vb2_dma_contig_plane_dma_addr(dst_buf, 1);
> > +               pfb->base_c.size = ctx->q_data[MTK_Q_DATA_DST].sizeimage[1];
> > +       }
> > +       mtk_v4l2_debug(1,
> > +               "id=%d Framebuf  pfb=%p VA=%p Y_DMA=%pad C_DMA=%pad Size=%zx frame_count = %d",
> > +               dst_buf->index, pfb,
> > +               pfb->base_y.va, &pfb->base_y.dma_addr,
> > +               &pfb->base_c.dma_addr, pfb->base_y.size,
> > +               ctx->decoded_frame_cnt);
> > +
> > +       return pfb;
> > +}
> > +
> > +static void vb2ops_vdec_buf_request_complete(struct vb2_buffer *vb)
> > +{
> > +       struct mtk_vcodec_ctx *ctx = vb2_get_drv_priv(vb->vb2_queue);
> > +
> > +       v4l2_ctrl_request_complete(vb->req_obj.req, &ctx->ctrl_hdl);
> > +}
> > +
> > +static int fops_media_request_validate(struct media_request *mreq)
> > +{
> > +       const unsigned int buffer_cnt = vb2_request_buffer_cnt(mreq);
> > +       struct mtk_vcodec_ctx *ctx = NULL;
> > +       struct media_request_object *req_obj;
> > +       struct v4l2_ctrl_handler *parent_hdl, *hdl;
> > +       struct v4l2_ctrl *ctrl;
> > +       unsigned int i;
> > +
> > +       switch (buffer_cnt) {
> > +       case 1:
> > +               /* We expect exactly one buffer with the request */
> > +               break;
> > +       case 0:
> > +               mtk_v4l2_err("No buffer provided with the request");
> > +               return -ENOENT;
> > +       default:
> > +               mtk_v4l2_err("Too many buffers (%d) provided with the request",
> > +                            buffer_cnt);
> > +               return -EINVAL;
> > +       }
> > +
> > +       list_for_each_entry(req_obj, &mreq->objects, list) {
> > +               struct vb2_buffer *vb;
> > +
> > +               if (vb2_request_object_is_buffer(req_obj)) {
> > +                       vb = container_of(req_obj, struct vb2_buffer, req_obj);
> > +                       ctx = vb2_get_drv_priv(vb->vb2_queue);
> > +                       break;
> > +               }
> > +       }
> > +
> > +       if (!ctx) {
> > +               mtk_v4l2_err("Cannot find buffer for request");
> > +               return -ENOENT;
> > +       }
> > +
> > +       parent_hdl = &ctx->ctrl_hdl;
> > +
> > +       hdl = v4l2_ctrl_request_hdl_find(mreq, parent_hdl);
> > +       if (!hdl) {
> > +               mtk_v4l2_err("Cannot find control handler for request\n");
> > +               return -ENOENT;
> > +       }
> > +
> > +       for (i = 0; i < NUM_CTRLS; i++) {
> > +               if (mtk_stateless_controls[i].codec_type != ctx->current_codec)
> > +                       continue;
> > +               if (!mtk_stateless_controls[i].needed_in_request)
> > +                       continue;
> > +
> > +               ctrl = v4l2_ctrl_request_hdl_ctrl_find(hdl,
> > +                                         mtk_stateless_controls[i].cfg.id);
> > +               if (!ctrl) {
> > +                       mtk_v4l2_err("Missing required codec control\n");
> > +                       return -ENOENT;
> > +               }
> > +       }
> > +
> > +       v4l2_ctrl_request_hdl_put(hdl);
> > +
> > +       return vb2_request_validate(mreq);
> > +}
> > +
> > +static void mtk_vdec_worker(struct work_struct *work)
> > +{
> > +       struct mtk_vcodec_ctx *ctx =
> > +               container_of(work, struct mtk_vcodec_ctx, decode_work);
> > +       struct mtk_vcodec_dev *dev = ctx->dev;
> > +       struct vb2_v4l2_buffer *vb2_v4l2_src, *vb2_v4l2_dst;
> > +       struct vb2_buffer *vb2_src;
> > +       struct mtk_vcodec_mem *bs_src;
> > +       struct mtk_video_dec_buf *dec_buf_src;
> > +       struct media_request *src_buf_req;
> > +       struct vdec_fb *dst_buf;
> > +       bool res_chg = false;
> > +       int ret;
> > +
> > +       vb2_v4l2_src = v4l2_m2m_next_src_buf(ctx->m2m_ctx);
> > +       if (vb2_v4l2_src == NULL) {
> > +               v4l2_m2m_job_finish(dev->m2m_dev_dec, ctx->m2m_ctx);
> > +               mtk_v4l2_debug(1, "[%d] no available source buffer", ctx->id);
> > +               return;
> > +       }
> > +
> > +       vb2_v4l2_dst = v4l2_m2m_next_dst_buf(ctx->m2m_ctx);
> > +       if (vb2_v4l2_dst == NULL) {
> > +               v4l2_m2m_job_finish(dev->m2m_dev_dec, ctx->m2m_ctx);
> > +               mtk_v4l2_debug(1, "[%d] no available destination buffer", ctx->id);
> > +               return;
> > +       }
> > +
> > +       vb2_src = &vb2_v4l2_src->vb2_buf;
> > +       dec_buf_src = container_of(vb2_v4l2_src, struct mtk_video_dec_buf,
> > +                                  m2m_buf.vb);
> > +       bs_src = &dec_buf_src->bs_buffer;
> > +
> > +       mtk_v4l2_debug(3, "[%d] (%d) id=%d, vb=%p buf_info = %p",
> > +                       ctx->id, src_buf->vb2_queue->type,
> > +                       src_buf->index, src_buf, src_buf_info);
> > +
> > +       bs_src->va = vb2_plane_vaddr(vb2_src, 0);
> > +       bs_src->dma_addr = vb2_dma_contig_plane_dma_addr(vb2_src, 0);
> > +       bs_src->size = (size_t)vb2_src->planes[0].bytesused;
> > +       if (!bs_src->va) {
> > +               v4l2_m2m_job_finish(dev->m2m_dev_dec, ctx->m2m_ctx);
> > +               mtk_v4l2_err("[%d] id=%d source buffer is NULL", ctx->id,
> > +                            vb2_src->index);
> > +               return;
> > +       }
> > +
> > +       mtk_v4l2_debug(3, "[%d] Bitstream VA=%p DMA=%pad Size=%zx vb=%p",
> > +                       ctx->id, buf->va, &buf->dma_addr, buf->size, src_buf);
> > +       /* Apply request controls. */
> > +       src_buf_req = vb2_src->req_obj.req;
> > +       if (src_buf_req)
> > +               v4l2_ctrl_request_setup(src_buf_req, &ctx->ctrl_hdl);
> > +       else
> > +               mtk_v4l2_err("vb2 buffer media request is NULL");
> > +
> > +       dst_buf = vdec_get_cap_buffer(ctx, vb2_v4l2_dst);
> > +       v4l2_m2m_buf_copy_metadata(vb2_v4l2_src, vb2_v4l2_dst, true);
> > +       ret = vdec_if_decode(ctx, bs_src, dst_buf, &res_chg);
> > +       if (ret) {
> > +               mtk_v4l2_err(
> > +                       " <===[%d], src_buf[%d] sz=0x%zx pts=%llu vdec_if_decode() ret=%d res_chg=%d===>",
> > +                       ctx->id, vb2_src->index, bs_src->size,
> > +                       vb2_src->timestamp, ret, res_chg);
> > +               if (ret == -EIO) {
> > +                       mutex_lock(&ctx->lock);
> > +                       dec_buf_src->error = true;
> > +                       mutex_unlock(&ctx->lock);
> > +               }
> > +       }
> > +
> > +       mtk_vdec_stateless_set_dst_payload(ctx, dst_buf);
> > +
> > +       v4l2_m2m_buf_done_and_job_finish(dev->m2m_dev_dec, ctx->m2m_ctx,
> > +               ret ? VB2_BUF_STATE_ERROR : VB2_BUF_STATE_DONE);
> > +
> > +       v4l2_ctrl_request_complete(src_buf_req, &ctx->ctrl_hdl);
> > +}
> > +
> > +static void vb2ops_vdec_stateless_buf_queue(struct vb2_buffer *vb)
> > +{
> > +       struct mtk_vcodec_ctx *ctx = vb2_get_drv_priv(vb->vb2_queue);
> > +       struct vb2_v4l2_buffer *vb2_v4l2 = to_vb2_v4l2_buffer(vb);
> > +
> > +       mtk_v4l2_debug(3, "[%d] (%d) id=%d, vb=%p",
> > +                       ctx->id, vb->vb2_queue->type,
> > +                       vb->index, vb);
> > +
> > +       mutex_lock(&ctx->lock);
> > +       v4l2_m2m_buf_queue(ctx->m2m_ctx, vb2_v4l2);
> > +       mutex_unlock(&ctx->lock);
> > +       if (vb->vb2_queue->type != V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
> > +               return;
> > +
> > +       mtk_v4l2_debug(3, "(%d) id=%d, bs=%p",
> > +               vb->vb2_queue->type, vb->index, src_buf);
> > +
> > +       /* If an OUTPUT buffer, we may need to update the state */
> > +       if (ctx->state == MTK_STATE_INIT) {
> > +               ctx->state = MTK_STATE_HEADER;
> > +               mtk_v4l2_debug(1, "Init driver from init to header.");
>
> This state thing seems just something to make the rest
> of the stateful-based driver happy, right?

Correct - if anything we should either use more of the state here
(i.e. set the error state when relevant) or move the state entirely in
the stateful part of the driver.

>
> Makes me wonder a bit if just splitting the stateless part to its
> own driver, wouldn't make your maintenance easier.
>
> What's the motivation for sharing the driver?

Technically you could do it both ways. Separating the driver would
result in some boilerplate code and buffer-management structs
duplication (unless we keep the shared part under another module - but
in this case we are basically in the same situation as now). Also
despite using different userspace-facing ABIs, MT8173 and MT8183
follow a similar architecture and a similar firmware interface.
Considering these similarities it seems simpler from an architectural
point of view to have all the Mediatek codec support under the same
driver. It also probably results in less code.

That being said, the split can probably be improved as you pointed out
with this state variable. But the current split is not too bad IMHO,
at least not worse than how the code was originally.

>
> > +       } else {
> > +               mtk_v4l2_debug(3, "[%d] already init driver %d",
> > +                               ctx->id, ctx->state);
> > +       }
> > +}
> > +
> > +static int mtk_vdec_flush_decoder(struct mtk_vcodec_ctx *ctx)
> > +{
> > +       bool res_chg;
> > +
> > +       return vdec_if_decode(ctx, NULL, NULL, &res_chg);
> > +}
> > +
> > +static const struct v4l2_ctrl_ops mtk_vcodec_dec_ctrl_ops = {
> > +       .g_volatile_ctrl = mtk_vdec_g_v_ctrl,
> > +};
> > +
> > +static int mtk_vcodec_dec_ctrls_setup(struct mtk_vcodec_ctx *ctx)
> > +{
> > +       struct v4l2_ctrl *ctrl;
> > +       unsigned int i;
> > +
> > +       v4l2_ctrl_handler_init(&ctx->ctrl_hdl, NUM_CTRLS);
> > +       if (ctx->ctrl_hdl.error) {
> > +               mtk_v4l2_err("v4l2_ctrl_handler_init failed\n");
> > +               return ctx->ctrl_hdl.error;
> > +       }
> > +
> > +       ctrl = v4l2_ctrl_new_std(&ctx->ctrl_hdl,
> > +                               &mtk_vcodec_dec_ctrl_ops,
> > +                               V4L2_CID_MIN_BUFFERS_FOR_CAPTURE,
> > +                               0, 32, 1, 1);
> > +       ctrl->flags |= V4L2_CTRL_FLAG_VOLATILE;
>
> Hm, this volatile control for MIN_BUFFERS_FOR_CAPTURE seems
> to return the DPB size. However, isn't this something userspace already knows?

True, but that's also a control the driver is supposed to provide per
the spec IIUC.

>
> > +
> > +       for (i = 0; i < NUM_CTRLS; i++) {
> > +               struct v4l2_ctrl_config cfg = mtk_stateless_controls[i].cfg;
> > +
> > +               v4l2_ctrl_new_custom(&ctx->ctrl_hdl, &cfg, NULL);
> > +               if (ctx->ctrl_hdl.error) {
> > +                       mtk_v4l2_err("Adding control %d failed %d",
> > +                                       i, ctx->ctrl_hdl.error);
> > +                       return ctx->ctrl_hdl.error;
> > +               }
> > +       }
> > +
> > +       v4l2_ctrl_handler_setup(&ctx->ctrl_hdl);
> > +
> > +       return 0;
> > +}
> > +
> > +const struct media_device_ops mtk_vcodec_media_ops = {
> > +       .req_validate   = fops_media_request_validate,
> > +       .req_queue      = v4l2_m2m_request_queue,
> > +};
> > +
> > +static void mtk_init_vdec_params(struct mtk_vcodec_ctx *ctx)
> > +{
> > +       struct vb2_queue *src_vq;
> > +
> > +       src_vq = v4l2_m2m_get_vq(ctx->m2m_ctx,
> > +                                V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE);
> > +
> > +       /* Support request api for output plane */
> > +       src_vq->supports_requests = true;
> > +       src_vq->requires_requests = true;
> > +}
> > +
> > +static int vb2ops_vdec_out_buf_validate(struct vb2_buffer *vb)
> > +{
>
> I have to admit I do not remember exactly the reason,
> but this should set the buffer field to V4L2_FIELD_NONE.

Right, I see all other drivers are doing this. Done.

Cheers,
Alex.