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

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Date: Thu, 15 Feb 2024 11:29:42 +0100
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Chun-Kuang Hu <chunkuang.hu@...nel.org>,
 Matthias Brugger <matthias.bgg@...il.com>,
 Mauro Carvalho Chehab <mchehab@...nel.org>,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
 Moudy Ho <moudy.ho@...iatek.com>
Subject: Re: [PATCH 6/9] media: platform: mtk-mdp3: drop calling
 cmdq_pkt_finalize()

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

> 
> 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;