linux-kernel - Re: [RESEND, PATCH v13 10/12] soc: mediatek: cmdq: add polling function

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Message-ID: <2dfb6a69-c325-9caf-e11b-bf0f0fbf4bb6@gmail.com>
Date:   Fri, 23 Aug 2019 16:05:27 +0200
From:   Matthias Brugger <matthias.bgg@...il.com>
To:     Bibby Hsieh <bibby.hsieh@...iatek.com>,
        Jassi Brar <jassisinghbrar@...il.com>,
        Rob Herring <robh+dt@...nel.org>, CK HU <ck.hu@...iatek.com>
Cc:     Daniel Kurtz <djkurtz@...omium.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, srv_heupstream@...iatek.com,
        Sascha Hauer <kernel@...gutronix.de>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Nicolas Boichat <drinkcat@...omium.org>,
        YT Shen <yt.shen@...iatek.com>,
        Daoyuan Huang <daoyuan.huang@...iatek.com>,
        Jiaguang Zhang <jiaguang.zhang@...iatek.com>,
        Dennis-YC Hsieh <dennis-yc.hsieh@...iatek.com>,
        Houlong Wei <houlong.wei@...iatek.com>, ginny.chen@...iatek.com
Subject: Re: [RESEND, PATCH v13 10/12] soc: mediatek: cmdq: add polling
 function



On 20/08/2019 10:49, Bibby Hsieh wrote:
> add polling function in cmdq helper functions
> 
> Signed-off-by: Bibby Hsieh <bibby.hsieh@...iatek.com>
> Reviewed-by: CK Hu <ck.hu@...iatek.com>
> ---
>  drivers/soc/mediatek/mtk-cmdq-helper.c   | 28 ++++++++++++++++++++++++
>  include/linux/mailbox/mtk-cmdq-mailbox.h |  1 +
>  include/linux/soc/mediatek/mtk-cmdq.h    | 15 +++++++++++++
>  3 files changed, 44 insertions(+)
> 
> diff --git a/drivers/soc/mediatek/mtk-cmdq-helper.c b/drivers/soc/mediatek/mtk-cmdq-helper.c
> index e3d5b0be8e79..c53f8476c68d 100644
> --- a/drivers/soc/mediatek/mtk-cmdq-helper.c
> +++ b/drivers/soc/mediatek/mtk-cmdq-helper.c
> @@ -221,6 +221,34 @@ int cmdq_pkt_clear_event(struct cmdq_pkt *pkt, u16 event)
>  }
>  EXPORT_SYMBOL(cmdq_pkt_clear_event);
>  
> +int cmdq_pkt_poll(struct cmdq_pkt *pkt, u8 subsys,
> +		  u16 offset, u32 value, u32 mask)
> +{
> +	struct cmdq_instruction *inst;
> +
> +	if (mask != 0xffffffff) {

Is this necessary? Can't we just always set the mask, even if it's 0xffffffff?

Regarding interfaces, depending on how often you expect the mask being ~0 we
might think of adding a cmdq_pkt_poll_mask call.
What I want to say, if in the end most of the callers will use the mask with
0xffffffff, then we should add a call cmdq_pkt_poll_mask which actually allows
to set the mask and let cmdq_pkt_poll set the mask in it's function body.
As I already said, this depends on how often you think a caller will use/not-use
the mask.
Does this make sense?

> +		inst = cmdq_pkt_append_command(pkt);
> +		if (!inst)
> +			return -ENOMEM;
> +
> +		inst->op = CMDQ_CODE_MASK;
> +		inst->value = ~mask;
> +		offset = offset | 0x1;
> +	}
> +
> +	inst = cmdq_pkt_append_command(pkt);
> +	if (!inst)
> +		return -ENOMEM;
> +
> +	inst->op = CMDQ_CODE_POLL;
> +	inst->value = value;
> +	inst->offset = offset;
> +	inst->subsys = subsys;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(cmdq_pkt_poll);
> +
>  static int cmdq_pkt_finalize(struct cmdq_pkt *pkt)
>  {
>  	struct cmdq_instruction *inst;
> diff --git a/include/linux/mailbox/mtk-cmdq-mailbox.h b/include/linux/mailbox/mtk-cmdq-mailbox.h
> index c8adedefaf42..9e3502945bc1 100644
> --- a/include/linux/mailbox/mtk-cmdq-mailbox.h
> +++ b/include/linux/mailbox/mtk-cmdq-mailbox.h
> @@ -46,6 +46,7 @@
>  enum cmdq_code {
>  	CMDQ_CODE_MASK = 0x02,
>  	CMDQ_CODE_WRITE = 0x04,
> +	CMDQ_CODE_POLL = 0x08,
>  	CMDQ_CODE_JUMP = 0x10,
>  	CMDQ_CODE_WFE = 0x20,
>  	CMDQ_CODE_EOC = 0x40,
> diff --git a/include/linux/soc/mediatek/mtk-cmdq.h b/include/linux/soc/mediatek/mtk-cmdq.h
> index 9618debb9ceb..a345870a6d10 100644
> --- a/include/linux/soc/mediatek/mtk-cmdq.h
> +++ b/include/linux/soc/mediatek/mtk-cmdq.h
> @@ -99,6 +99,21 @@ int cmdq_pkt_wfe(struct cmdq_pkt *pkt, u16 event);
>   */
>  int cmdq_pkt_clear_event(struct cmdq_pkt *pkt, u16 event);
>  
> +/**
> + * cmdq_pkt_poll() - Append polling command to the CMDQ packet, ask GCE to
> + *		     execute an instruction that wait for a specified hardware
> + *		     register to check for the value. All GCE hardware
> + *		     threads will be blocked by this instruction.
> + * @pkt:	the CMDQ packet
> + * @subsys:	the CMDQ sub system code
> + * @offset:	register offset from CMDQ sub system
> + * @value:	the specified target register value
> + * @mask:	the specified target register mask
> + *
> + * Return: 0 for success; else the error code is returned
> + */
> +int cmdq_pkt_poll(struct cmdq_pkt *pkt, u8 subsys,
> +		  u16 offset, u32 value, u32 mask);
>  /**
>   * cmdq_pkt_flush_async() - trigger CMDQ to asynchronously execute the CMDQ
>   *                          packet and call back at the end of done packet
>