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

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Message-ID: <1566878857.29523.4.camel@mtksdaap41>
Date:   Tue, 27 Aug 2019 12:07:37 +0800
From:   Bibby Hsieh <bibby.hsieh@...iatek.com>
To:     Matthias Brugger <matthias.bgg@...il.com>
CC:     Jassi Brar <jassisinghbrar@...il.com>,
        Rob Herring <robh+dt@...nel.org>, CK HU <ck.hu@...iatek.com>,
        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 Fri, 2019-08-23 at 16:05 +0200, Matthias Brugger wrote:
> 
> 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?

It's better to have two function: cmdq_pkt_poll_mask and cmdq_pkt_poll,
client can choose which they need by themselves.

Thanks for the comments.

Bibby
> > +		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
> >