linux-kernel - Re: [PATCH 6/9] media: platform: mtk-mdp3: drop calling cmdq_pkt

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Message-ID: <143420847d70fd03763863c1a0a60751591d5240.camel@mediatek.com>
Date: Thu, 22 Feb 2024 03:11:26 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
	"chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>, "mchehab@...nel.org"
	<mchehab@...nel.org>, Moudy Ho (何宗原)
	<Moudy.Ho@...iatek.com>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "matthias.bgg@...il.com"
	<matthias.bgg@...il.com>, "angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>
CC: Jason-JH Lin (林睿祥) <Jason-JH.Lin@...iatek.com>
Subject: Re: [PATCH 6/9] media: platform: mtk-mdp3: drop calling
 cmdq_pkt_finalize()

Hi, Moudy:

On Fri, 2024-02-16 at 08:56 +0100, AngeloGioacchino Del Regno wrote:
> Il 16/02/24 07:20, Moudy Ho (何宗原) ha scritto:
> > On Thu, 2024-02-15 at 11:29 +0100, AngeloGioacchino Del Regno
> > wrote:
> > > Il 15/02/24 01:49, Chun-Kuang Hu ha scritto:
> > > > Because client driver has the information of struct
> > > > cmdq_client, so
> > > > it's not necessary to store struct cmdq_client in struct
> > > > cmdq_pkt.
> > > > cmdq_pkt_finalize() use struct cmdq_client in struct cmdq_pkt,
> > > > so
> > > > it's
> > > > going to be abandoned. Therefore, use cmdq_pkt_eoc() and
> > > > cmdq_pkt_nop()
> > > > to replace cmdq_pkt_finalize().
> > > 
> > > No, it's not because cmdq_pkt_finalize() has cmdq_client, but
> > > because
> > > we want
> > > finer grain control over the CMDQ packets, as not all cases
> > > require
> > > the NOP
> > > packet to be appended after EOC.
> > > 
> > > Besides, honestly I'm not even sure if the NOP is always required
> > > in
> > > MDP3, so...
> > > 
> > > ...Moudy, you know the MDP3 way better than anyone else - can you
> > > please
> > > check if NOP is actually needed here?
> > > 
> > > Thanks!
> > > Angelo
> > > 
> > 
> > Hi Angelo,
> > 
> > After confirming with the hardware designer and performing the
> > video
> > playback test, it was discovered that MDP3 is capable of excluding
> > the
> > NOP(jump) instruction.
> > 
> 
> Thank you for this extremely fast clarification.

As discuss with Jason, there is one precondition that mdp3 could drop
nop. mpd3 still need to append jump command in the end of packet. The
precondition is that if the jump command is append by mailbox
controller, then client driver is not necessary to append nop. But
currently, mailbox controller just modify nop to jump, not append jump.
Because this modification is not related to this series of removing
pkt->cl, so I would keep append nop in the end of packet for mdp3
driver.

Regards,
CK

> 
> Cheers,
> Angelo
> 
> > Sincerely,
> > Moudy
> > > > 
> > > > Signed-off-by: Chun-Kuang Hu <chunkuang.hu@...nel.org>
> > > > ---
> > > >    drivers/media/platform/mediatek/mdp3/mtk-mdp3-cmdq.c | 3 ++-
> > > >    drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c | 2 ++
> > > >    drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.h | 1 +
> > > >    3 files changed, 5 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-
> > > > cmdq.c
> > > > b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-cmdq.c
> > > > index 6adac857a477..a420d492d879 100644
> > > > --- a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-cmdq.c
> > > > +++ b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-cmdq.c
> > > > @@ -471,7 +471,8 @@ int mdp_cmdq_send(struct mdp_dev *mdp,
> > > > struct
> > > > mdp_cmdq_param *param)
> > > >    		dev_err(dev, "mdp_path_config error\n");
> > > >    		goto err_free_path;
> > > >    	}
> > > > -	cmdq_pkt_finalize(&cmd->pkt);
> > > > +	cmdq_pkt_eoc(&cmd->pkt);
> > > > +	cmdq_pkt_nop(&cmd->pkt, mdp->cmdq_shift_pa);
> > > >    
> > > >    	for (i = 0; i < num_comp; i++)
> > > >    		memcpy(&comps[i], path->comps[i].comp,
> > > > diff --git a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-
> > > > core.c
> > > > b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
> > > > index 94f4ed78523b..2214744c937c 100644
> > > > --- a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
> > > > +++ b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c
> > > > @@ -231,6 +231,8 @@ static int mdp_probe(struct platform_device
> > > > *pdev)
> > > >    		goto err_put_scp;
> > > >    	}
> > > >    
> > > > +	mdp->cmdq_shift_pa = cmdq_get_shift_pa(mdp->cmdq_clt-
> > > > >chan);
> > > > +
> > > >    	init_waitqueue_head(&mdp->callback_wq);
> > > >    	ida_init(&mdp->mdp_ida);
> > > >    	platform_set_drvdata(pdev, mdp);
> > > > diff --git a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-
> > > > core.h
> > > > b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.h
> > > > index 7e21d226ceb8..ed61e0bb69ee 100644
> > > > --- a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.h
> > > > +++ b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.h
> > > > @@ -83,6 +83,7 @@ struct mdp_dev {
> > > >    	u32					id_count;
> > > >    	struct ida				mdp_ida;
> > > >    	struct cmdq_client			*cmdq_clt;
> > > > +	u8					cmdq_shift_pa;
> > > >    	wait_queue_head_t			callback_wq;
> > > >    
> > > >    	struct v4l2_device			v4l2_dev;
> > > 
> > > 
> 
> 
> 
>