Re: [PATCH v7, 05/15] media: mtk-vcodec: Call v4l2_m2m_set_dst_buffered() set capture buffer buffered

[Nicolas Dufresne]

Le mercredi 23 février 2022 à 11:39 +0800, Yunfei Dong a écrit :
> lat thread: output queue      \
>                                -> lat hardware -> lat trans buffer
>             lat trans buffer  /
> 
> core thread: capture queue     \
>                                 ->core hardware -> capture queue
>              lat trans buffer  /
> 
> Lat and core work in different thread, setting capture buffer buffered.

... so that output queue buffers (bitstream) can be process regardless if there
is available capture buffers.

I have concerns around the usefulness of running a dedicated thread to drive the
lat and the core blocks. Having 3 threads (counting the m2m worker thread) here
increase the complexity. The hardware is asynchronous by definition. I think
this patch will go away after a proper rework of the driver thread model here.

> 
> Signed-off-by: Yunfei Dong <yunfei.dong@xxxxxxxxxxxx>
> ---
>  drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_stateless.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> 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 5aebf88f997b..23a154c4e321 100644
> --- a/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_stateless.c
> +++ b/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_stateless.c
> @@ -314,6 +314,9 @@ static void mtk_init_vdec_params(struct mtk_vcodec_ctx *ctx)
>  	src_vq = v4l2_m2m_get_vq(ctx->m2m_ctx,
>  				 V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE);
>  
> +	if (ctx->dev->vdec_pdata->hw_arch != MTK_VDEC_PURE_SINGLE_CORE)
> +		v4l2_m2m_set_dst_buffered(ctx->m2m_ctx, 1);
> +
>  	/* Support request api for output plane */
>  	src_vq->supports_requests = true;
>  	src_vq->requires_requests = true;