linux-kernel - Re: [PATCH v2 13/14] soc: mediatek: cmdq: add wait no clear event function

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Date:   Wed, 11 Dec 2019 10:04:47 +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 v2 13/14] soc: mediatek: cmdq: add wait no clear event
 function

Hi, Dennis:

On Wed, 2019-11-27 at 09:58 +0800, Dennis YC Hsieh wrote:
> Add wait no clear event function in cmdq helper functions to wait specific
> event without clear to 0 after receive it.
> 
> Signed-off-by: Dennis YC Hsieh <dennis-yc.hsieh@...iatek.com>
> ---
>  drivers/soc/mediatek/mtk-cmdq-helper.c | 15 +++++++++++++++
>  include/linux/soc/mediatek/mtk-cmdq.h  | 10 ++++++++++
>  2 files changed, 25 insertions(+)
> 
> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c b/drivers/soc/mediatek/mtk-cmdq-helper.c
> index 10a9b4481e58..6f270fadfb50 100644
> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> @@ -330,6 +330,21 @@ int cmdq_pkt_wfe(struct cmdq_pkt *pkt, u16 event)
>  }
>  EXPORT_SYMBOL(cmdq_pkt_wfe);
>  
> +int cmdq_pkt_wait_no_clear(struct cmdq_pkt *pkt, u16 event)
> +{
> +	struct cmdq_instruction inst = { {0} };
> +
> +	if (event >= CMDQ_MAX_EVENT)
> +		return -EINVAL;
> +
> +	inst.op = CMDQ_CODE_WFE;
> +	inst.value = CMDQ_WFE_WAIT | CMDQ_WFE_WAIT_VALUE;
> +	inst.event = event;
> +
> +	return cmdq_pkt_append_command(pkt, inst);
> +}
> +EXPORT_SYMBOL(cmdq_pkt_wait_no_clear);

So the wait command has two version, one is wait and then clear event,
another is wait and not clear event. The name of cmdq_pkt_wfe() is 'wait
for event', so it's trivial that we think it does not clear event. I've
three suggestion for this:

1. Let cmdq_pkt_wfe() wait and not clear event, and
cmdq_pkt_wfe_clear_event() wait and clear event.

or 
2. Let cmdq_pkt_wfe() has a parameter to indicate that clear event or
not after wait.

or
3. Let cmdq_pkt_wfe() wait and not clear event, and not provide wait and
clear event version. For DRM and MDP, I think both just need wait and
not clear event.

Regards,
CK


> +
>  int cmdq_pkt_clear_event(struct cmdq_pkt *pkt, u16 event)
>  {
>  	struct cmdq_instruction inst = { {0} };
> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h b/include/linux/soc/mediatek/mtk-cmdq.h
> index d15d8c941992..40bc61ad8d31 100644
> --- a/include/linux/soc/mediatek/mtk-cmdq.h
> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> @@ -149,6 +149,16 @@ int cmdq_pkt_write_s_value(struct cmdq_pkt *pkt, dma_addr_t addr,
>   */
>  int cmdq_pkt_wfe(struct cmdq_pkt *pkt, u16 event);
>  
> +/**
> + * cmdq_pkt_wait_no_clear() - Append wait for event command to the CMDQ packet,
> + *			      without update event to 0 after receive it.
> + * @pkt:	the CMDQ packet
> + * @event:	the desired event type to wait
> + *
> + * Return: 0 for success; else the error code is returned
> + */
> +int cmdq_pkt_wait_no_clear(struct cmdq_pkt *pkt, u16 event);
> +
>  /**
>   * cmdq_pkt_clear_event() - append clear event command to the CMDQ packet
>   * @pkt:	the CMDQ packet