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Date:   Wed, 19 Aug 2020 13:45:04 -0600
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     Peng Fan <peng.fan@nxp.com>
Cc:     "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
        "o.rempel@pengutronix.de" <o.rempel@pengutronix.de>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "linux-remoteproc@vger.kernel.org" <linux-remoteproc@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "shawnguo@kernel.org" <shawnguo@kernel.org>,
        "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
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        "festevam@gmail.com" <festevam@gmail.com>,
        dl-linux-imx <linux-imx@nxp.com>,
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        <linux-arm-kernel@lists.infradead.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Subject: Re: [PATCH 04/10] remoteproc: imx_rproc: make syscon optional
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On Wed, Aug 19, 2020 at 12:51:27AM +0000, Peng Fan wrote:
> > Subject: Re: [PATCH 04/10] remoteproc: imx_rproc: make syscon optional
> > 
> > Hi Peng,
> > 
> > On Fri, Jul 24, 2020 at 04:08:07PM +0800, Peng Fan wrote:
> > > Make syscon optional, since i.MX8QM/QXP/7ULP not have SRC to control
> > M4.
> > > But currently i.MX8QM/QXP/7ULP not added, so still check regmap when
> > > start/stop to avoid unhappy things.
> > 
> > On the i.MX8QM/QXP/7ULP processors, the remote processors are not
> > handled by the remoteproc cores, as implemented in this patch.  In such a
> > scenario how does the remoteproc core know the remote processor has
> > crashed and how does it recover from such a condition?
> 
> For 7ULP dual boot case, A7 is under control of M4, so if m4 crash, I suppose
> A7 would not work properly.

In that case I assume the whole system gets rebooted, which puts the A7 in a
state where it can "attach" with the M4 again.

> 
> For 8QM/QXP partition case, M4 is in a standalone partition, if M4 crash or
> reboot, the system controller unit will restart M4 and notify Acore that M4
> restart.

And how does that notification work exactly?  Does rproc_report_crash() get
called somewhere in that process in order for the remoteproc core to attach to
the M4 again?

Many thanks for the help,
Mathieu

> 
> Thanks,
> Peng.
> 
> > 
> > Thanks,
> > Mathieu
> > 
> > >
> > > Reviewed-by: Richard Zhu <hongxing.zhu@nxp.com>
> > > Signed-off-by: Peng Fan <peng.fan@nxp.com>
> > > ---
> > >  drivers/remoteproc/imx_rproc.c | 11 +++++++++--
> > >  1 file changed, 9 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/remoteproc/imx_rproc.c
> > > b/drivers/remoteproc/imx_rproc.c index 82594a800a1b..4fad5c0b1c05
> > > 100644
> > > --- a/drivers/remoteproc/imx_rproc.c
> > > +++ b/drivers/remoteproc/imx_rproc.c
> > > @@ -162,6 +162,9 @@ static int imx_rproc_start(struct rproc *rproc)
> > >  	struct device *dev = priv->dev;
> > >  	int ret;
> > >
> > > +	if (!priv->regmap)
> > > +		return -EOPNOTSUPP;
> > > +
> > >  	ret = regmap_update_bits(priv->regmap, dcfg->src_reg,
> > >  				 dcfg->src_mask, dcfg->src_start);
> > >  	if (ret)
> > > @@ -177,6 +180,9 @@ static int imx_rproc_stop(struct rproc *rproc)
> > >  	struct device *dev = priv->dev;
> > >  	int ret;
> > >
> > > +	if (!priv->regmap)
> > > +		return -EOPNOTSUPP;
> > > +
> > >  	ret = regmap_update_bits(priv->regmap, dcfg->src_reg,
> > >  				 dcfg->src_mask, dcfg->src_stop);
> > >  	if (ret)
> > > @@ -325,9 +331,10 @@ static int imx_rproc_probe(struct platform_device
> > *pdev)
> > >  	regmap = syscon_regmap_lookup_by_phandle(np, "syscon");
> > >  	if (IS_ERR(regmap)) {
> > >  		dev_err(dev, "failed to find syscon\n");
> > > -		return PTR_ERR(regmap);
> > > +		regmap = NULL;
> > > +	} else {
> > > +		regmap_attach_dev(dev, regmap, &config);
> > >  	}
> > > -	regmap_attach_dev(dev, regmap, &config);
> > >
> > >  	/* set some other name then imx */
> > >  	rproc = rproc_alloc(dev, "imx-rproc", &imx_rproc_ops,
> > > --
> > > 2.16.4
> > >