Re: [PATCH v6, 06/15] media: mtk-vcodec: Refactor get and put capture buffer flow

From: Nicolas Dufresne
Date: Fri Jan 28 2022 - 16:49:30 EST

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Hi Yunfei,

thanks for you work, see comments below...

Le samedi 22 janvier 2022 à 11:53 +0800, Yunfei Dong a écrit :
> For lat and core decode in parallel, need to get capture buffer
> when core start to decode and put capture buffer to display
> list when core decode done.
>
> Signed-off-by: Yunfei Dong <yunfei.dong@xxxxxxxxxxxx>
> ---
> .../mtk-vcodec/mtk_vcodec_dec_stateless.c | 121 ++++++++++++------
> .../platform/mtk-vcodec/mtk_vcodec_drv.h | 5 +-
> .../mtk-vcodec/vdec/vdec_h264_req_if.c | 16 ++-
> 3 files changed, 102 insertions(+), 40 deletions(-)
>
> diff --git a/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_stateless.c b/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_stateless.c
> index 23a154c4e321..6d481410bf89 100644
> --- a/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_stateless.c
> +++ b/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_stateless.c
> @@ -108,37 +108,87 @@ static const struct mtk_codec_framesizes mtk_vdec_framesizes[] = {
>
> #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)
> +static void mtk_vdec_stateless_out_to_done(struct mtk_vcodec_ctx *ctx,
> + struct mtk_vcodec_mem *bs, int error)
> {
> - 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];
> + struct mtk_video_dec_buf *out_buf;
> + struct vb2_v4l2_buffer *vb;
>
> - 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];
> + if (!bs) {
> + mtk_v4l2_err("Free bitstream buffer fail.");
> + return;
> + }
> + out_buf = container_of(bs, struct mtk_video_dec_buf, bs_buffer);
> + vb = &out_buf->m2m_buf.vb;
>
> - vb2_set_plane_payload(&vb->vb2_buf, 1, cap_c_size);
> + mtk_v4l2_debug(2, "Free bitsteam buffer id = %d to done_list",
> + vb->vb2_buf.index);
> +
> + v4l2_m2m_src_buf_remove(ctx->m2m_ctx);
> + if (error) {
> + v4l2_m2m_buf_done(vb, VB2_BUF_STATE_ERROR);
> + if (error == -EIO)
> + out_buf->error = true;
> + } else {
> + v4l2_m2m_buf_done(vb, VB2_BUF_STATE_DONE);
> }
> }
>
> -static struct vdec_fb *vdec_get_cap_buffer(struct mtk_vcodec_ctx *ctx,
> - struct vb2_v4l2_buffer *vb2_v4l2)
> +static void mtk_vdec_stateless_cap_to_disp(struct mtk_vcodec_ctx *ctx,
> + struct vdec_fb *fb, int error)
> {
> - 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;
> + struct mtk_video_dec_buf *vdec_frame_buf;
> + struct vb2_v4l2_buffer *vb;
> + unsigned int cap_y_size, cap_c_size;
> +
> + if (!fb) {
> + mtk_v4l2_err("Free frame buffer fail.");
> + return;
> + }
> + vdec_frame_buf = container_of(fb, struct mtk_video_dec_buf,
> + frame_buffer);
> + vb = &vdec_frame_buf->m2m_buf.vb;
> +
> + cap_y_size = ctx->q_data[MTK_Q_DATA_DST].sizeimage[0];
> + cap_c_size = ctx->q_data[MTK_Q_DATA_DST].sizeimage[1];
> +
> + v4l2_m2m_dst_buf_remove(ctx->m2m_ctx);
>
> - pfb->base_y.va = NULL;
> + vb2_set_plane_payload(&vb->vb2_buf, 0, cap_y_size);
> + if (ctx->q_data[MTK_Q_DATA_DST].fmt->num_planes == 2)
> + vb2_set_plane_payload(&vb->vb2_buf, 1, cap_c_size);
> +
> + mtk_v4l2_debug(2, "Free frame buffer id = %d to done_list",
> + vb->vb2_buf.index);
> + if (error)
> + v4l2_m2m_buf_done(vb, VB2_BUF_STATE_ERROR);
> + else
> + v4l2_m2m_buf_done(vb, VB2_BUF_STATE_DONE);
> +}
> +
> +static struct vdec_fb *vdec_get_cap_buffer(struct mtk_vcodec_ctx *ctx)
> +{
> + struct mtk_video_dec_buf *framebuf;
> + struct vb2_v4l2_buffer *vb2_v4l2;
> + struct vb2_buffer *dst_buf;
> + struct vdec_fb *pfb;
> +
> + vb2_v4l2 = v4l2_m2m_next_dst_buf(ctx->m2m_ctx);
> + if (!vb2_v4l2) {
> + mtk_v4l2_debug(1, "[%d] dst_buf empty!!", ctx->id);
> + return NULL;
> + }
> +
> + dst_buf = &vb2_v4l2->vb2_buf;
> + framebuf = container_of(vb2_v4l2, struct mtk_video_dec_buf, m2m_buf.vb);
> +
> + pfb = &framebuf->frame_buffer;
> + pfb->base_y.va = vb2_plane_vaddr(dst_buf, 0);
> 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 = NULL;
> + 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];
> @@ -162,12 +212,11 @@ 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_v4l2_buffer *vb2_v4l2_src;
> 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;
>
> @@ -178,13 +227,6 @@ static void mtk_vdec_worker(struct work_struct *work)
> return;
> }
>
> - vb2_v4l2_dst = v4l2_m2m_next_dst_buf(ctx->m2m_ctx);
> - if (!vb2_v4l2_dst) {
> - 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);
> @@ -193,9 +235,15 @@ static void mtk_vdec_worker(struct work_struct *work)
> mtk_v4l2_debug(3, "[%d] (%d) id=%d, vb=%p", ctx->id,
> vb2_src->vb2_queue->type, vb2_src->index, vb2_src);
>
> - bs_src->va = NULL;
> + 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, bs_src->va, &bs_src->dma_addr, bs_src->size, vb2_src);
> @@ -206,9 +254,7 @@ static void mtk_vdec_worker(struct work_struct *work)
> 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);

Please keep using this helper, it is specially crafted to ease maintenance.

> - ret = vdec_if_decode(ctx, bs_src, dst_buf, &res_chg);
> + ret = vdec_if_decode(ctx, bs_src, NULL, &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,
> @@ -220,12 +266,9 @@ static void mtk_vdec_worker(struct work_struct *work)
> }
> }
>
> - 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);
> -
> + mtk_vdec_stateless_out_to_done(ctx, bs_src, ret);

v4l2_m2m_buf_done_and_job_finish() was specially crafted to prevent developer
from implementing the signalling of the request at the wrong moment. This patch
broke this strict ordering. The relevant comment in the helper function:

/*
* If the request API is being used, returning the OUTPUT
* (src) buffer will wake-up any process waiting on the
* request file descriptor.
*
* Therefore, return the CAPTURE (dst) buffer first,
* to avoid signalling the request file descriptor
* before the CAPTURE buffer is done.
*/

In short, as request signalling is bound to the src buffer, with this change you
signal the request too early, which may lead userland to think it can DQ the
capture buffer. I see exactly that happening when running with GStreamer, which
strictly rely on the request polling. Please keep using
v4l2_m2m_buf_done_and_job_finish(), and move it into
mtk_vdec_stateless_cap_to_disp().

> v4l2_ctrl_request_complete(src_buf_req, &ctx->ctrl_hdl);
> + v4l2_m2m_job_finish(dev->m2m_dev_dec, ctx->m2m_ctx);
> }
>
> static void vb2ops_vdec_stateless_buf_queue(struct vb2_buffer *vb)
> @@ -358,6 +401,8 @@ const struct mtk_vcodec_dec_pdata mtk_vdec_8183_pdata = {
> .uses_stateless_api = true,
> .worker = mtk_vdec_worker,
> .flush_decoder = mtk_vdec_flush_decoder,
> + .cap_to_disp = mtk_vdec_stateless_cap_to_disp,
> + .get_cap_buffer = vdec_get_cap_buffer,
> .is_subdev_supported = false,
> .hw_arch = MTK_VDEC_PURE_SINGLE_CORE,
> };
> @@ -376,6 +421,8 @@ const struct mtk_vcodec_dec_pdata mtk_lat_sig_core_pdata = {
> .uses_stateless_api = true,
> .worker = mtk_vdec_worker,
> .flush_decoder = mtk_vdec_flush_decoder,
> + .cap_to_disp = mtk_vdec_stateless_cap_to_disp,
> + .get_cap_buffer = vdec_get_cap_buffer,
> .is_subdev_supported = true,
> .hw_arch = MTK_VDEC_LAT_SINGLE_CORE,
> };
> diff --git a/drivers/media/platform/mtk-vcodec/mtk_vcodec_drv.h b/drivers/media/platform/mtk-vcodec/mtk_vcodec_drv.h
> index 2d1d878692ca..e0b7d2fda632 100644
> --- a/drivers/media/platform/mtk-vcodec/mtk_vcodec_drv.h
> +++ b/drivers/media/platform/mtk-vcodec/mtk_vcodec_drv.h
> @@ -353,7 +353,8 @@ enum mtk_vdec_hw_arch {
> * @ctrls_setup: init vcodec dec ctrls
> * @worker: worker to start a decode job
> * @flush_decoder: function that flushes the decoder
> - *
> + * @get_cap_buffer: get capture buffer from capture queue
> + * @cap_to_disp: put capture buffer to disp list
> * @vdec_vb2_ops: struct vb2_ops
> *
> * @vdec_formats: supported video decoder formats
> @@ -375,6 +376,8 @@ struct mtk_vcodec_dec_pdata {
> int (*ctrls_setup)(struct mtk_vcodec_ctx *ctx);
> void (*worker)(struct work_struct *work);
> int (*flush_decoder)(struct mtk_vcodec_ctx *ctx);
> + struct vdec_fb *(*get_cap_buffer)(struct mtk_vcodec_ctx *ctx);
> + void (*cap_to_disp)(struct mtk_vcodec_ctx *ctx, struct vdec_fb *fb, int error);
>
> struct vb2_ops *vdec_vb2_ops;
>
> diff --git a/drivers/media/platform/mtk-vcodec/vdec/vdec_h264_req_if.c b/drivers/media/platform/mtk-vcodec/vdec/vdec_h264_req_if.c
> index 43542de11e9c..36f3dc1fbe3b 100644
> --- a/drivers/media/platform/mtk-vcodec/vdec/vdec_h264_req_if.c
> +++ b/drivers/media/platform/mtk-vcodec/vdec/vdec_h264_req_if.c
> @@ -670,32 +670,42 @@ static void vdec_h264_slice_deinit(void *h_vdec)
> }
>
> static int vdec_h264_slice_decode(void *h_vdec, struct mtk_vcodec_mem *bs,
> - struct vdec_fb *fb, bool *res_chg)
> + struct vdec_fb *unused, bool *res_chg)
> {
> struct vdec_h264_slice_inst *inst = h_vdec;
> const struct v4l2_ctrl_h264_decode_params *dec_params =
> get_ctrl_ptr(inst->ctx, V4L2_CID_STATELESS_H264_DECODE_PARAMS);
> struct vdec_vpu_inst *vpu = &inst->vpu;
> + struct mtk_video_dec_buf *src_buf_info;
> + struct mtk_video_dec_buf *dst_buf_info;
> + struct vdec_fb *fb;
> u32 data[2];
> u64 y_fb_dma;
> u64 c_fb_dma;
> int err;
>
> + inst->num_nalu++;
> /* bs NULL means flush decoder */
> if (!bs)
> return vpu_dec_reset(vpu);
>
> + fb = inst->ctx->dev->vdec_pdata->get_cap_buffer(inst->ctx);
> + src_buf_info = container_of(bs, struct mtk_video_dec_buf, bs_buffer);
> + dst_buf_info = container_of(fb, struct mtk_video_dec_buf, frame_buffer);
> +
> y_fb_dma = fb ? (u64)fb->base_y.dma_addr : 0;
> c_fb_dma = fb ? (u64)fb->base_c.dma_addr : 0;
>
> mtk_vcodec_debug(inst, "+ [%d] FB y_dma=%llx c_dma=%llx va=%p",
> - ++inst->num_nalu, y_fb_dma, c_fb_dma, fb);
> + inst->num_nalu, y_fb_dma, c_fb_dma, fb);
>
> inst->vsi_ctx.dec.bs_dma = (uint64_t)bs->dma_addr;
> inst->vsi_ctx.dec.y_fb_dma = y_fb_dma;
> inst->vsi_ctx.dec.c_fb_dma = c_fb_dma;
> inst->vsi_ctx.dec.vdec_fb_va = (u64)(uintptr_t)fb;
>
> + v4l2_m2m_buf_copy_metadata(&src_buf_info->m2m_buf.vb,
> + &dst_buf_info->m2m_buf.vb, true);
> get_vdec_decode_parameters(inst);
> data[0] = bs->size;
> /*
> @@ -734,6 +744,8 @@ static int vdec_h264_slice_decode(void *h_vdec, struct mtk_vcodec_mem *bs,
>
> memcpy(&inst->vsi_ctx, inst->vpu.vsi, sizeof(inst->vsi_ctx));
> mtk_vcodec_debug(inst, "\n - NALU[%d]", inst->num_nalu);
> +
> + inst->ctx->dev->vdec_pdata->cap_to_disp(inst->ctx, fb, 0);
> return 0;
>
> err_free_fb_out:

Next message: Tom Zanussi: "Re: [PATCH v2 0/2] tracing: Misc bugfixes"
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