linux-kernel - Re: [PATCH 4/5] i3c: master: svc return actual transfer data len

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Message-ID: <ZTA/X333KBXDN49p@lizhi-Precision-Tower-5810>
Date:   Wed, 18 Oct 2023 16:26:07 -0400
From:   Frank Li <Frank.li@....com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     alexandre.belloni@...tlin.com, conor.culhane@...vaco.com,
        joe@...ches.com, linux-i3c@...ts.infradead.org,
        linux-kernel@...r.kernel.org, imx@...ts.linux.dev
Subject: Re: [PATCH 4/5] i3c: master: svc return actual transfer data len

On Tue, Oct 17, 2023 at 04:10:07PM +0200, Miquel Raynal wrote:
> Hi Frank,
> 
> Frank.Li@....com wrote on Mon, 16 Oct 2023 11:46:31 -0400:
> 
> > I3C allow devices early terminate data transfer. So set "actual" to
> > indicate how much data get by i3c_priv_xfer.
> > 
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> >  drivers/i3c/master/svc-i3c-master.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> > index 3570b709cf60..444825aafa6f 100644
> > --- a/drivers/i3c/master/svc-i3c-master.c
> > +++ b/drivers/i3c/master/svc-i3c-master.c
> > @@ -138,6 +138,7 @@ struct svc_i3c_cmd {
> >  	const void *out;
> >  	unsigned int len;
> >  	unsigned int actual_len;
> > +	struct i3c_priv_xfer *xfer;
> >  	bool continued;
> >  };
> >  
> > @@ -1045,6 +1046,7 @@ static int svc_i3c_master_xfer(struct svc_i3c_master *master,
> >  
> >  	if (readl(master->regs + SVC_I3C_MERRWARN) & SVC_I3C_MERRWARN_NACK) {
> >  		ret = -ENXIO;
> > +		*actual_len = 0;
> >  		goto emit_stop;
> >  	}
> >  
> > @@ -1062,6 +1064,7 @@ static int svc_i3c_master_xfer(struct svc_i3c_master *master,
> >  	 */
> >  	if (SVC_I3C_MSTATUS_IBIWON(reg)) {
> >  		ret = -ENXIO;
> > +		*actual_len = 0;
> >  		goto emit_stop;
> >  	}
> >  
> > @@ -1157,6 +1160,9 @@ static void svc_i3c_master_start_xfer_locked(struct svc_i3c_master *master)
> >  					  cmd->addr, cmd->in, cmd->out,
> >  					  cmd->len, &cmd->actual_len,
> >  					  cmd->continued);
> > +		if (cmd->xfer)
> > +			cmd->xfer->actual = cmd->actual_len;
> 
> Just to be sure, wouldn't it be more natural to always fill cmd->xfer
> rather than checking it here?

cmd->xfer is NULL for i2c and ccc transfer. So need check it. 
I will add comments here

Frank
> 
> > +
> >  		if (ret)
> >  			break;
> >  	}
> > @@ -1344,6 +1350,7 @@ static int svc_i3c_master_priv_xfers(struct i3c_dev_desc *dev,
> >  	for (i = 0; i < nxfers; i++) {
> >  		struct svc_i3c_cmd *cmd = &xfer->cmds[i];
> >  
> > +		cmd->xfer = xfers + i;
> 
> Please follow the same pattern as below: = &xfers[i]
> 
> >  		cmd->addr = master->addrs[data->index];
> >  		cmd->rnw = xfers[i].rnw;
> >  		cmd->in = xfers[i].rnw ? xfers[i].data.in : NULL;
> 
> 
> Thanks,
> Miquèl