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Date: Mon, 17 Oct 2022 11:33:35 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Peng Fan <peng.fan@....com>
Cc: "Peng Fan (OSS)" <peng.fan@....nxp.com>,
"andersson@...nel.org" <andersson@...nel.org>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"krzysztof.kozlowski+dt@...aro.org"
<krzysztof.kozlowski+dt@...aro.org>,
"shawnguo@...nel.org" <shawnguo@...nel.org>,
"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
"kernel@...gutronix.de" <kernel@...gutronix.de>,
"festevam@...il.com" <festevam@...il.com>,
dl-linux-imx <linux-imx@....com>,
"linux-remoteproc@...r.kernel.org" <linux-remoteproc@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V7 6/7] remoteproc: imx_rproc: request mbox channel later
On Mon, Oct 17, 2022 at 03:13:16AM +0000, Peng Fan wrote:
> Hi Mathieu,
>
> > Subject: Re: [PATCH V7 6/7] remoteproc: imx_rproc: request mbox channel
> > later
> >
> > On Fri, Oct 14, 2022 at 11:10:36AM +0800, Peng Fan (OSS) wrote:
> > > From: Peng Fan <peng.fan@....com>
> > >
> > > 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@....com>
> > > ---
> > > drivers/remoteproc/imx_rproc.c | 39
> > > ++++++++++++++++++++++++++++++++--
> > > 1 file changed, 37 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/remoteproc/imx_rproc.c
> > > b/drivers/remoteproc/imx_rproc.c index 917e6db39572..1183de84a4c0
> > > 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;
> > > }
> > > @@ -592,6 +600,22 @@ static void imx_rproc_kick(struct rproc *rproc,
> > > int vqid)
> > >
> > > static int imx_rproc_attach(struct rproc *rproc) {
> > > + return imx_rproc_xtr_mbox_init(rproc); }
> > > +
> > > +static int imx_rproc_detach(struct rproc *rproc) {
> > > + struct imx_rproc *priv = rproc->priv;
> > > + const struct imx_rproc_dcfg *dcfg = priv->dcfg;
> > > +
> > > + if (dcfg->method != IMX_RPROC_SCU_API)
> > > + return -EOPNOTSUPP;
> > > +
> > > + if (imx_sc_rm_is_resource_owned(priv->ipc_handle, priv->rsrc_id))
> > > + return -EOPNOTSUPP;
> > > +
> > > + imx_rproc_free_mbox(rproc);
> > > +
> > > return 0;
> > > }
> > >
> > > @@ -610,6 +634,7 @@ static struct resource_table
> > > *imx_rproc_get_loaded_rsc_table(struct rproc *rproc static const struct
> > rproc_ops imx_rproc_ops = {
> > > .prepare = imx_rproc_prepare,
> > > .attach = imx_rproc_attach,
> > > + .detach = imx_rproc_detach,
> > > .start = imx_rproc_start,
> > > .stop = imx_rproc_stop,
> > > .kick = imx_rproc_kick,
> > > @@ -720,6 +745,9 @@ 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;
> > > +
> >
> > You did exactly the same things as in V6. I asked you why this is needed and
> > all you did is point me to the code in _probe(), which I can read on my own.
> >
>
> Sorry for not wrote down clear.
>
> > Again - why is this needed when we know it will be done in start() and
> > attach()?
>
> start() and attach() not able to handle mbox defer probe. So I add
We are finally at the heart of the problem. I had to go look at the
implementation of imx_rproc_xtr_mbox_init() to understand that it can return
-EPROBE_DEFER. Had there been a comment in the code to highlight _why_ the if()
condition is needed, I would have understood right away and all this waste of
time avoided.
> the mbox requesting in probe to handle mbox defer probe, and add
> a check when requesting mbox channel in start/attach. During first
> time attach/start remote core, the imx_rproc_xtr_mbox_init just
> return, because channel requested in probe flow.
>
> Since mbox requested in probe, why still add it in start() and attach()?
> It is to support runtime stop and start(M4 is under control of Linux),
> to support runtime detach(only for i.MX8QM/QXP attach recovery,
> m4 out of control from linux) and attach.
>
> Thanks,
> Peng.
> >
> >
> > > if (!of_get_property(dev->of_node, "mbox-names", NULL))
> > > return 0;
> > >
> > > @@ -749,8 +777,15 @@ 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)
> > > --
> > > 2.37.1
> > >
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