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Message-ID: <9f6d7408e78fe74bb96983004f9ee00a2467e95d.camel@mediatek.com>
Date: Tue, 27 Aug 2024 02:50:03 +0000
From: Yunfei Dong (董云飞) <Yunfei.Dong@...iatek.com>
To: "sebastian.fricke@...labora.com" <sebastian.fricke@...labora.com>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
"frkoenig@...omium.org" <frkoenig@...omium.org>, "stevecho@...omium.org"
<stevecho@...omium.org>, "nhebert@...omium.org" <nhebert@...omium.org>,
"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"nicolas.dufresne@...labora.com" <nicolas.dufresne@...labora.com>,
"daniel.almeida@...labora.com" <daniel.almeida@...labora.com>,
"daniel@...ll.ch" <daniel@...ll.ch>, Project_Global_Chrome_Upstream_Group
<Project_Global_Chrome_Upstream_Group@...iatek.com>,
"benjamin.gaignard@...labora.com" <benjamin.gaignard@...labora.com>,
"hverkuil-cisco@...all.nl" <hverkuil-cisco@...all.nl>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>, "hsinyi@...omium.org"
<hsinyi@...omium.org>, "angelogioacchino.delregno@...labora.com"
<angelogioacchino.delregno@...labora.com>, "nfraprado@...labora.com"
<nfraprado@...labora.com>
Subject: Re: [PATCH v4 5/7] media: mediatek: vcodec: store source vb2 buffer
Hi Sebastian,
Thanks for your suggestion.
On Fri, 2024-08-23 at 16:14 +0200, Sebastian Fricke wrote:
> Hey Yunfei,
>
> On 07.08.2024 16:24, Yunfei Dong wrote:
> > Store the current vb2 buffer when lat need to decode again.
> > Then lat work can get the same vb2 buffer directly next time.
>
> I would reword this with:
>
> Store the current source buffer in the specific data for the IC. When
> the LAT needs to retry a decode it can pick that buffer directly.
>
> ---
>
> Additionally, this is not a good commit description as you just say
> what
> you do, but you don't say WHY this needs to happen, why is it
> necessary?
> What does it improve, is this a preparation patch for another, a fix
> for
> something or an improvement of performance?
>
>
> more below...
>
> >
> > Signed-off-by: Yunfei Dong <yunfei.dong@...iatek.com>
> > ---
> > .../mediatek/vcodec/decoder/mtk_vcodec_dec_drv.h | 2 ++
> > .../vcodec/decoder/mtk_vcodec_dec_stateless.c | 11
> > ++++++++---
> > 2 files changed, 10 insertions(+), 3 deletions(-)
> >
> > diff --git
> > a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv
> > .h
> > b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv
> > .h
> > index 1fabe8c5b7a4..0817be73f8e0 100644
> > ---
> > a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv
> > .h
> > +++
> > b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_drv
> > .h
> > @@ -155,6 +155,7 @@ struct mtk_vcodec_dec_pdata {
> > * @last_decoded_picinfo: pic information get from latest decode
> > * @empty_flush_buf: a fake size-0 capture buffer that indicates
> > flush. Used
> > * for stateful decoder.
> > + * @last_vb2_v4l2_src: the backup of current source buffer.
>
> I think last is confusing in this context especially as there is for
> example in the m2m_ctx:
> * @last_src_buf: indicate the last source buffer for draining
> * @next_buf_last: next capture queud buffer will be tagged as last
> or:
> * v4l2_m2m_last_buf() - return last buffer from the list of ready
> buffers
>
> I think a better name would be:
>
> * @cur_src_buf: current source buffer with the bitstream data for
> the latest decode
>
> > * @is_flushing: set to true if flushing is in progress.
> > *
> > * @current_codec: current set input codec, in V4L2 pixel format
> > @@ -201,6 +202,7 @@ struct mtk_vcodec_dec_ctx {
> > struct work_struct decode_work;
> > struct vdec_pic_info last_decoded_picinfo;
> > struct v4l2_m2m_buffer empty_flush_buf;
> > + struct vb2_v4l2_buffer *last_vb2_v4l2_src;
>
> Likewise here:
>
> struct vb2_v4l2_buffer *cur_src_buf;
>
> > bool is_flushing;
> >
> > u32 current_codec;
> > diff --git
> > a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_sta
> > teless.c
> > b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_sta
> > teless.c
> > index 2a7e4fe24ed3..8aa379872ddc 100644
> > ---
> > a/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_sta
> > teless.c
> > +++
> > b/drivers/media/platform/mediatek/vcodec/decoder/mtk_vcodec_dec_sta
> > teless.c
> > @@ -320,7 +320,7 @@ static void mtk_vdec_worker(struct work_struct
> > *work)
> > struct mtk_vcodec_dec_ctx *ctx =
> > container_of(work, struct mtk_vcodec_dec_ctx,
> > decode_work);
> > struct mtk_vcodec_dec_dev *dev = ctx->dev;
> > - struct vb2_v4l2_buffer *vb2_v4l2_src;
> > + struct vb2_v4l2_buffer *vb2_v4l2_src = ctx->last_vb2_v4l2_src;
>
> And here:
>
> struct vb2_v4l2_buffer *vb2_v4l2_src = ctx->cur_src_buf;
>
> > struct vb2_buffer *vb2_src;
> > struct mtk_vcodec_mem *bs_src;
> > struct mtk_video_dec_buf *dec_buf_src;
> > @@ -329,7 +329,7 @@ static void mtk_vdec_worker(struct work_struct
> > *work)
> > bool res_chg = false;
> > int ret;
> >
> > - vb2_v4l2_src = v4l2_m2m_next_src_buf(ctx->m2m_ctx);
> > + vb2_v4l2_src = vb2_v4l2_src ? vb2_v4l2_src :
> > v4l2_m2m_next_src_buf(ctx->m2m_ctx);
>
> Please add a comment above this line that explains why this search
> can
> be made, explaining why this buffer is still valid in this call and
> when
> we pick the next source buffer.
>
As the commit wrote, if the driver need to decoder again, need to use
the last remove source buffer to decode again, not to get one new.
Regards,
Yunfei Dong
> Regards,
> Sebastian Fricke
>
> > if (!vb2_v4l2_src) {
> > v4l2_m2m_job_finish(dev->m2m_dev_dec, ctx->m2m_ctx);
> > mtk_v4l2_vdec_dbg(1, ctx, "[%d] no available source
> > buffer", ctx->id);
> > @@ -383,8 +383,13 @@ static void mtk_vdec_worker(struct work_struct
> > *work)
> > v4l2_ctrl_request_complete(src_buf_req, &ctx-
> > >ctrl_hdl);
> > v4l2_m2m_buf_done_and_job_finish(dev->m2m_dev_dec, ctx-
> > >m2m_ctx, state);
> > } else {
> > - if (ret != -EAGAIN)
> > + if (ret != -EAGAIN) {
> > v4l2_m2m_src_buf_remove(ctx->m2m_ctx);
> > + ctx->last_vb2_v4l2_src = NULL;
> > + } else {
> > + ctx->last_vb2_v4l2_src = vb2_v4l2_src;
> > + }
> > +
> > v4l2_m2m_job_finish(dev->m2m_dev_dec, ctx->m2m_ctx);
> > }
> > }
> > --
> > 2.46.0
> >
> >
>
>
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