linux-kernel - Re: [PATCH v3 11/13] soc: mediatek: cmdq: add jump function

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Date:   Fri, 28 Feb 2020 22:59:41 +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>,
        <srv_heupstream@...iatek.com>,
        "Ming-Fan Chen" <ming-fan.chen@...iatek.com>
Subject: Re: [PATCH v3 11/13] soc: mediatek: cmdq: add jump function

Hi, Dennis:

On Fri, 2020-02-28 at 21:44 +0800, Dennis YC Hsieh wrote:
> Add jump function so that client can jump to any address which
> contains instruction.
> 
> Signed-off-by: Dennis YC Hsieh <dennis-yc.hsieh@...iatek.com>
> ---
>  drivers/soc/mediatek/mtk-cmdq-helper.c | 12 ++++++++++++
>  include/linux/soc/mediatek/mtk-cmdq.h  | 11 +++++++++++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c b/drivers/soc/mediatek/mtk-cmdq-helper.c
> index 58fec634dcf1..bbc68a7c81e9 100644
> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> @@ -372,6 +372,18 @@ int cmdq_pkt_assign(struct cmdq_pkt *pkt, u16 reg_idx, u32 value)
>  }
>  EXPORT_SYMBOL(cmdq_pkt_assign);
>  
> +int cmdq_pkt_jump(struct cmdq_pkt *pkt, dma_addr_t addr)
> +{
> +	struct cmdq_client *cl = pkt->cl;
> +	struct cmdq_instruction inst = { {0} };
> +
> +	inst.op = CMDQ_CODE_JUMP;
> +	inst.offset = 1;

Symbolize the value '1'.

> +	inst.value = addr >> cmdq_mbox_shift(cl->chan);

If you write as 'cmdq_mbox_shift(pkt->cl->chan)', you could drop local
variable 'cl'.

Regards,
CK

> +	return cmdq_pkt_append_command(pkt, inst);
> +}
> +EXPORT_SYMBOL(cmdq_pkt_jump);
> +
>  int cmdq_pkt_finalize(struct cmdq_pkt *pkt)
>  {
>  	struct cmdq_instruction inst = { {0} };
> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h b/include/linux/soc/mediatek/mtk-cmdq.h
> index 99e77155f967..1a6c56f3bec1 100644
> --- a/include/linux/soc/mediatek/mtk-cmdq.h
> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> @@ -213,6 +213,17 @@ 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_jump() - Append jump command to the CMDQ packet, ask GCE
> + *		     to execute an instruction that change current thread PC to
> + *		     a physical address which should contains more instruction.
> + * @pkt:        the CMDQ packet
> + * @addr:       physical address of target instruction buffer
> + *
> + * Return: 0 for success; else the error code is returned
> + */
> +int cmdq_pkt_jump(struct cmdq_pkt *pkt, dma_addr_t addr);
> +
>  /**
>   * cmdq_pkt_finalize() - Append EOC and jump command to pkt.
>   * @pkt:	the CMDQ packet