linux-kernel - Re: [PATCH 3/6] i3c: master: svc: fix ibi may not return mandatory data byte

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Message-ID: <ZS70zTwcGOjxB6MS@lizhi-Precision-Tower-5810>
Date:   Tue, 17 Oct 2023 16:55:41 -0400
From:   Frank Li <Frank.li@....com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     conor.culhane@...vaco.com, alexandre.belloni@...tlin.com,
        joe@...ches.com, linux-i3c@...ts.infradead.org,
        linux-kernel@...r.kernel.org, imx@...ts.linux.dev
Subject: Re: [PATCH 3/6] i3c: master: svc: fix ibi may not return mandatory
 data byte

On Tue, Oct 17, 2023 at 04:27:07PM +0200, Miquel Raynal wrote:
> Hi Frank,
> 
> Frank.Li@....com wrote on Mon, 16 Oct 2023 11:32:29 -0400:
> 
> > MSTATUS[RXPEND] is only updated after the data transfer cycle started. This
> > creates an issue when the I3C clock is slow, and the CPU is running fast
> > enough that MSTATUS[RXPEND] may not be updated when the code reach checking
> > point. As a result, mandatory data are being missed.
> 
> 					can be missed.
> 
> > Add a wait for MSTATUS[COMPLETE] to ensure that all mandatory data already
> > in FIFO.
> 
> is already in the FIFO
> 
> > 
> > Fixes: dd3c52846d59 ("i3c: master: svc: Add Silvaco I3C master driver")
> > Cc: stable@...r.kernel.org
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> >  drivers/i3c/master/svc-i3c-master.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
> > index 0f57a5f75e39..c252446b2bc5 100644
> > --- a/drivers/i3c/master/svc-i3c-master.c
> > +++ b/drivers/i3c/master/svc-i3c-master.c
> > @@ -331,6 +331,7 @@ static int svc_i3c_master_handle_ibi(struct svc_i3c_master *master,
> >  	struct i3c_ibi_slot *slot;
> >  	unsigned int count;
> >  	u32 mdatactrl;
> > +	int ret, val;
> >  	u8 *buf;
> >  
> >  	slot = i3c_generic_ibi_get_free_slot(data->ibi_pool);
> > @@ -340,6 +341,13 @@ static int svc_i3c_master_handle_ibi(struct svc_i3c_master *master,
> >  	slot->len = 0;
> >  	buf = slot->data;
> >  
> > +	ret = readl_relaxed_poll_timeout(master->regs + SVC_I3C_MSTATUS, val,
> > +						SVC_I3C_MSTATUS_COMPLETE(val), 0, 1000);
> 
> Are you sure !MSTATUS_COMPLETE(val) is never a valid condition?
> Especially with non-mandatory bytes?
> 
> Also, are you sure of the indentation here?

If no-mandatory data, it is equal RDTERAM is 0. It takes some times to
change my slave code to create such test case.

Frank Li

> 
> > +	if (ret) {
> > +		dev_err(master->dev, "Timeout when polling for COMPLETE\n");
> > +		return ret;
> > +	}
> > +
> >  	while (SVC_I3C_MSTATUS_RXPEND(readl(master->regs + SVC_I3C_MSTATUS))  &&
> >  	       slot->len < SVC_I3C_FIFO_SIZE) {
> >  		mdatactrl = readl(master->regs + SVC_I3C_MDATACTRL);
> 
> 
> Thanks,
> Miquèl