linux-kernel - Re: [PATCH v1 10/12] soc: mediatek: cmdq: add loop function

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Date:   Fri, 22 Nov 2019 17:46:00 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Dennis YC Hsieh <dennis-yc.hsieh@...iatek.com>
CC:     Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Jassi Brar <jassisinghbrar@...il.com>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <wsd_upstream@...iatek.com>,
        Bibby Hsieh <bibby.hsieh@...iatek.com>,
        Houlong Wei <houlong.wei@...iatek.com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v1 10/12] soc: mediatek: cmdq: add loop function

Hi, Dennis:

On Thu, 2019-11-21 at 17:12 +0800, Dennis YC Hsieh wrote:
> Add finalize loop function in cmdq helper functions which loop whole pkt
> in gce hardware thread without cpu operation.
> 
> Signed-off-by: Dennis YC Hsieh <dennis-yc.hsieh@...iatek.com>
> ---
>  drivers/soc/mediatek/mtk-cmdq-helper.c |   41 ++++++++++++++++++++++++++++++++
>  include/linux/soc/mediatek/mtk-cmdq.h  |    8 +++++++
>  2 files changed, 49 insertions(+)
> 
> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c b/drivers/soc/mediatek/mtk-cmdq-helper.c
> index 4235cf8..3b10241 100644
> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> @@ -385,12 +385,27 @@ int cmdq_pkt_assign(struct cmdq_pkt *pkt, u16 reg_idx, u32 value)
>  }
>  EXPORT_SYMBOL(cmdq_pkt_assign);
>  
> +static bool cmdq_pkt_finalized(struct cmdq_pkt *pkt)
> +{
> +	struct cmdq_instruction *inst;
> +
> +	if (pkt->cmd_buf_size < 2 * CMDQ_INST_SIZE)
> +		return false;
> +
> +	inst = pkt->va_base + pkt->cmd_buf_size - 2 * CMDQ_INST_SIZE;
> +	return inst->op == CMDQ_CODE_EOC;
> +}
> +
>  static int cmdq_pkt_finalize(struct cmdq_pkt *pkt)
>  {
>  	struct cmdq_client *cl = pkt->cl;
>  	struct cmdq_instruction inst = { {0} };
>  	int err;
>  
> +	/* do not finalize twice */
> +	if (cmdq_pkt_finalized(pkt))
> +		return 0;
> +
>  	/* insert EOC and generate IRQ for each command iteration */
>  	inst.op = CMDQ_CODE_EOC;
>  	inst.value = CMDQ_EOC_IRQ_EN;
> @@ -406,6 +421,32 @@ static int cmdq_pkt_finalize(struct cmdq_pkt *pkt)
>  	return err;
>  }
>  
> +int cmdq_pkt_finalize_loop(struct cmdq_pkt *pkt)
> +{
> +	struct cmdq_client *cl = pkt->cl;
> +	struct cmdq_instruction inst = { {0} };
> +	int err;
> +
> +	/* do not finalize twice */
> +	if (cmdq_pkt_finalized(pkt))
> +		return 0;

Why not just export cmdq_pkt_finalize() for user and do not call
cmdq_pkt_finalize() in cmdq_pkt_flush_async(), so you don't need to
check this.

I would be more like to export API such as cmdq_pkt_eoc(),
cmdq_pkt_jump(), this would provide more flexibility for user to
assemble the command it want.

Regards,
CK

> +
> +	/* insert EOC and generate IRQ for each command iteration */
> +	inst.op = CMDQ_CODE_EOC;
> +	err = cmdq_pkt_append_command(pkt, inst);
> +	if (err < 0)
> +		return err;
> +
> +	/* JUMP abaolute to begin */
> +	inst.op = CMDQ_CODE_JUMP;
> +	inst.offset = 1;
> +	inst.value = pkt->pa_base >> cmdq_mbox_shift(cl->chan);
> +	err = cmdq_pkt_append_command(pkt, inst);
> +
> +	return err;
> +}
> +EXPORT_SYMBOL(cmdq_pkt_finalize_loop);
> +
>  static void cmdq_pkt_flush_async_cb(struct cmdq_cb_data data)
>  {
>  	struct cmdq_pkt *pkt = (struct cmdq_pkt *)data.data;
> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h b/include/linux/soc/mediatek/mtk-cmdq.h
> index b3474f2..77e8944 100644
> --- a/include/linux/soc/mediatek/mtk-cmdq.h
> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> @@ -203,6 +203,14 @@ int cmdq_pkt_poll_mask(struct cmdq_pkt *pkt, u8 subsys,
>  int cmdq_pkt_assign(struct cmdq_pkt *pkt, u16 reg_idx, u32 value);
>  
>  /**
> + * cmdq_pkt_finalize_loop() - Append EOC and jump command to loop pkt.
> + * @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
>   * @pkt:	the CMDQ packet