RE: [PATCH V6 6/7] remoteproc: imx_rproc: request mbox channel later

[Peng Fan]

Hi Mathieu,

> Subject: Re: [PATCH V6 6/7] remoteproc: imx_rproc: request mbox channel
> later
> 
> On Thu, Sep 29, 2022 at 02:17:03PM +0800, Peng Fan (OSS) wrote:
> > From: Peng Fan <peng.fan@xxxxxxx>
> >
> > It is possible that when remote processor crash, the communication
> > channel will be broken with garbage value in mailbox, such as when
> > Linux is issuing a message through mailbox, remote processor crashes,
> > we need free & rebuild the mailbox channels to make sure no garbage
> > value in mailbox channels.
> >
> > So move the request/free to start/stop for managing remote procesosr
> > in Linux, move to attach/detach for remote processor is out of control
> > of Linux.
> >
> > Previous, we just request mbox when attach for CM4 boot early before
> > Linux, but if mbox defer probe, remoteproc core will do resource
> > cleanup and corrupt resource table for later probe.
> >
> > So move request mbox ealier and still keep mbox request when attach
> > for self recovery case, but keep a check when request/free mbox.
> >
> > Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> > ---
> >  drivers/remoteproc/imx_rproc.c | 26 +++++++++++++++++++++++---
> >  1 file changed, 23 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/remoteproc/imx_rproc.c
> > b/drivers/remoteproc/imx_rproc.c index 8175c4c9aa22..bece44b46719
> > 100644
> > --- a/drivers/remoteproc/imx_rproc.c
> > +++ b/drivers/remoteproc/imx_rproc.c
> > @@ -84,6 +84,8 @@ struct imx_rproc_mem {
> >  #define ATT_CORE_MASK   0xffff
> >  #define ATT_CORE(I)     BIT((I))
> >
> > +static int imx_rproc_xtr_mbox_init(struct rproc *rproc); static void
> > +imx_rproc_free_mbox(struct rproc *rproc);
> >  static int imx_rproc_detach_pd(struct rproc *rproc);
> >
> >  struct imx_rproc {
> > @@ -357,6 +359,10 @@ static int imx_rproc_start(struct rproc *rproc)
> >  	struct arm_smccc_res res;
> >  	int ret;
> >
> > +	ret = imx_rproc_xtr_mbox_init(rproc);
> > +	if (ret)
> > +		return ret;
> > +
> >  	switch (dcfg->method) {
> >  	case IMX_RPROC_MMIO:
> >  		ret = regmap_update_bits(priv->regmap, dcfg->src_reg,
> > dcfg->src_mask, @@ -407,6 +413,8 @@ static int imx_rproc_stop(struct
> > rproc *rproc)
> >
> >  	if (ret)
> >  		dev_err(dev, "Failed to stop remote core\n");
> > +	else
> > +		imx_rproc_free_mbox(rproc);
> >
> >  	return ret;
> >  }
> > @@ -592,7 +600,7 @@ static void imx_rproc_kick(struct rproc *rproc,
> > int vqid)
> >
> >  static int imx_rproc_attach(struct rproc *rproc)  {
> > -	return 0;
> > +	return imx_rproc_xtr_mbox_init(rproc);
> >  }
> >
> >  static struct resource_table *imx_rproc_get_loaded_rsc_table(struct
> > rproc *rproc, size_t *table_sz) @@ -720,6 +728,9 @@ static int
> imx_rproc_xtr_mbox_init(struct rproc *rproc)
> >  	struct device *dev = priv->dev;
> >  	struct mbox_client *cl;
> >
> > +	if (priv->tx_ch && priv->rx_ch)
> > +		return 0;
> > +
> 
> Why is this needed?  The remoteproc core's state machine driven by rproc-
> >state guarantees that imx_rproc_start(), imx_rproc_stop() and
> imx_rproc_attach are not called more than once.
> 
> And why is imx_rproc_xtr_mbox_init() in imx_rproc_probe() not removed?

I not remove it, code piece in probe function:

        ret = imx_rproc_xtr_mbox_init(rproc);
        if (ret)
                goto err_put_wkq;

        ret = imx_rproc_addr_init(priv, pdev);
        if (ret) {
                dev_err(dev, "failed on imx_rproc_addr_init\n");
                goto err_put_mbox;
        }

        ret = imx_rproc_detect_mode(priv);
        if (ret)
                goto err_put_mbox;
> 
> >  	if (!of_get_property(dev->of_node, "mbox-names", NULL))
> >  		return 0;
> >
> > @@ -749,8 +760,15 @@ static void imx_rproc_free_mbox(struct rproc
> > *rproc)  {
> >  	struct imx_rproc *priv = rproc->priv;
> >
> > -	mbox_free_channel(priv->tx_ch);
> > -	mbox_free_channel(priv->rx_ch);
> > +	if (priv->tx_ch) {
> > +		mbox_free_channel(priv->tx_ch);
> > +		priv->tx_ch = NULL;
> > +	}
> > +
> > +	if (priv->rx_ch) {
> > +		mbox_free_channel(priv->rx_ch);
> > +		priv->rx_ch = NULL;
> > +	}
> >  }
> >
> >  static void imx_rproc_put_scu(struct rproc *rproc) @@ -779,6 +797,8
> > @@ static int imx_rproc_partition_notify(struct notifier_block *nb,
> >  	if (!((event & BIT(priv->rproc_pt)) && (*(u8 *)group ==
> IMX_SC_IRQ_GROUP_REBOOTED)))
> >  		return 0;
> >
> > +	imx_rproc_free_mbox(priv->rproc);
> 
> Why putting this here when it will be called again in imx_rproc_stop()?  If
> you need it for the attached scenario, create imx_rproc_detach() and add it
> there.

This is when got notification from CM4, Linux free the mbox channel. 
The noficiation only work when CM4 runs in separated partition, linux not
able to start/stop CM4.
Patch 7/7 attach recovery will move this out. Here is just free mbox after CM4
crash, and linux not has permission to stop CM4.

Thanks,
Peng.
> 
> > +
> >  	rproc_report_crash(priv->rproc, RPROC_WATCHDOG);
> >
> >  	pr_info("Partition%d reset!\n", priv->rproc_pt);
> > --
> > 2.37.1
> >