linux-kernel - Re: [PATCH 08/15] soc: mediatek: Add cmdq_pkt_finalize

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Date:   Tue, 19 Sep 2023 01:38:50 +0000
From:   CK Hu (胡俊光) <ck.hu@...iatek.com>
To:     "jassisinghbrar@...il.com" <jassisinghbrar@...il.com>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        Jason-JH Lin (林睿祥) 
        <Jason-JH.Lin@...iatek.com>,
        "chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Singo Chang (張興國) 
        <Singo.Chang@...iatek.com>,
        Johnson Wang (王聖鑫) 
        <Johnson.Wang@...iatek.com>,
        Jason-ch Chen (陳建豪) 
        <Jason-ch.Chen@...iatek.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Shawn Sung (宋孝謙) 
        <Shawn.Sung@...iatek.com>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        Nancy Lin (林欣螢) <Nancy.Lin@...iatek.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "conor+dt@...nel.org" <conor+dt@...nel.org>,
        Elvis Wang (王军) <Elvis.Wang@...iatek.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Project_Global_Chrome_Upstream_Group 
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH 08/15] soc: mediatek: Add cmdq_pkt_finalize_loop to CMDQ
 driver

Hi, Jason:

On Tue, 2023-09-19 at 03:21 +0800, Jason-JH.Lin wrote:
> Add cmdq_pkt_finalize_loop to CMDQ driver.
> 
> cmdq_pkt_finalize_loop appends end of command(EOC) instruction and
> jump to start of command buffer instruction to make the command
> buffer loopable.
> 
> Signed-off-by: Jason-JH.Lin <jason-jh.lin@...iatek.com>
> ---
>  drivers/soc/mediatek/mtk-cmdq-helper.c | 23 +++++++++++++++++++++++
>  include/linux/soc/mediatek/mtk-cmdq.h  |  8 ++++++++
>  2 files changed, 31 insertions(+)
> 
> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c
> b/drivers/soc/mediatek/mtk-cmdq-helper.c
> index 4be2a18a4a02..bbb127620bb3 100644
> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> @@ -475,6 +475,29 @@ int cmdq_pkt_finalize(struct cmdq_pkt *pkt)
>  }
>  EXPORT_SYMBOL(cmdq_pkt_finalize);
>  
> +int cmdq_pkt_finalize_loop(struct cmdq_pkt *pkt)
> +{
> +	struct cmdq_instruction inst = { {0} };
> +	int err;
> +
> +	/* insert EOC and generate IRQ for each command iteration */
> +	inst.op = CMDQ_CODE_EOC;
> +	inst.value = CMDQ_EOC_IRQ_EN;
> +	err = cmdq_pkt_append_command(pkt, inst);
> +	if (err < 0)
> +		return err;
> +
> +	/* JUMP to start of pkt */
> +	err = cmdq_pkt_jump(pkt, pkt->pa_base);
> +	if (err < 0)
> +		return err;

Could you explain the case that a loop thread would trigger an
interrupt? In DRM crc function, the loop thread need not to trigger
interrupt, so I'm curious about this.

Regards,
CK

> +
> +	pkt->loop = true;
> +
> +	return err;
> +}
> +EXPORT_SYMBOL(cmdq_pkt_finalize_loop);
> +
>  int cmdq_pkt_flush_async(struct cmdq_pkt *pkt)
>  {
>  	int err;
> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h
> b/include/linux/soc/mediatek/mtk-cmdq.h
> index 837ad8656adc..38a8e47da338 100644
> --- a/include/linux/soc/mediatek/mtk-cmdq.h
> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> @@ -323,6 +323,14 @@ int cmdq_pkt_jump(struct cmdq_pkt *pkt,
> dma_addr_t addr);
>   */
>  int cmdq_pkt_finalize(struct cmdq_pkt *pkt);
>  
> +/**
> + * cmdq_pkt_finalize_loop() - Append EOC and jump to start command.
> + * @pkt:	the CMDQ packet
> + *
> + * Return: 0 for success; else the error code is returned
> + */
> +int cmdq_pkt_finalize_loop(struct cmdq_pkt *pkt);
> +
>  /**
>   * cmdq_pkt_flush_async() - trigger CMDQ to asynchronously execute
> the CMDQ
>   *                          packet and call back at the end of done
> packet