RE: [PATCH V2] remoteproc: support self recovery after rproc crash

[Peng Fan]

> Subject: Re: [PATCH V2] remoteproc: support self recovery after rproc crash
> 
> Hi Peng,
> 
> On 1/26/22 09:51, Peng Fan (OSS) wrote:
> > From: Peng Fan <peng.fan@xxxxxxx>
> >
> > Current logic only support main processor to stop/start the remote
> > processor after rproc crash. However to SoC, such as i.MX8QM/QXP, the
> > remote processor could do self recovery after crash and trigger
> > watchdog reboot. It does not need main processor to load image,
> > stop/start M4 core.
> 
> 
> On stm32mp1 platform the remote processor watchdog generates an early
> interrupt that could be used to detach and reattach before the reset of the
> remote processor.
> I need to test race condition,but I suppose that this should works if the
> resource table is not reinitialized by the remote processor firmware.

In i.MX8QM/QXP partition setup, resource table will be reinitialized by
remote firmware.

> 
> Another option for the stm32mp1 is that remoteproc manages the reset of
> the remote processor.
> For instance this allows to save a core-dump before manually resetting the
> remote processor.
> But looks like this use case can be handled later, as mentioned below.
> 
> >
> > This patch add a new flag to indicate whether the SoC has self
> > recovery capability. And introduce two functions: rproc_self_recovery,
> > rproc_assisted_recovery for the two cases. Assisted recovery is as
> > before, let main processor to help recovery, while self recovery is
> > recover itself withou help. To self recovery, we only do detach and
> > attach.
> 
> 
> >
> > Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> > ---
> >
> > V2:
> >  Nothing change in V2.
> >  Only move this patch out from
> >
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatc
> >
> hwork.kernel.org%2Fproject%2Flinux-remoteproc%2Flist%2F%3Fseries%3D6
> 04
> >
> 364&amp;data=04%7C01%7Cpeng.fan%40nxp.com%7C9e8a4ea774124a896f
> ed08d9ef
> >
> e9ac6c%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637804609
> 168765154
> > %7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzI
> iLCJBTiI6I
> >
> k1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=ewUl7diAOfkomSQMiPDQ
> o5A6c2Hklgo
> > 8xYbMBk5A4Ic%3D&amp;reserved=0
> >
> >  drivers/remoteproc/remoteproc_core.c | 66
> ++++++++++++++++++++--------
> >  include/linux/remoteproc.h           |  2 +
> >  2 files changed, 49 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/remoteproc/remoteproc_core.c
> > b/drivers/remoteproc/remoteproc_core.c
> > index 69f51acf235e..4bd5544dab8f 100644
> > --- a/drivers/remoteproc/remoteproc_core.c
> > +++ b/drivers/remoteproc/remoteproc_core.c
> > @@ -1887,6 +1887,49 @@ static int __rproc_detach(struct rproc *rproc)
> >  	return 0;
> >  }
> >
> > +static int rproc_self_recovery(struct rproc *rproc) {
> > +	int ret;
> > +
> > +	mutex_unlock(&rproc->lock);
> > +	ret = rproc_detach(rproc);
> > +	mutex_lock(&rproc->lock);
> > +	if (ret)
> > +		return ret;
> 
> Here we would want to perform a core dump and manually reset the
> co-processor.

It is self recovery, not needed manual reset from main processor.

> I suppose that a new rproc ops could be called here in a next step.

Not very sure, but core dump could be added if needed.

> 
> > +
> > +	if (atomic_inc_return(&rproc->power) > 1)
> > +		return 0;
> 
> Do you identify a use case that needs to test rproc->power to skip the attach?
> If yes could you add a comment to describe it?

Just to avoid some error path. I think only when power is 1,
and self recovery could attach again.

> 
> > +	return rproc_attach(rproc);
> > +}
> > +
> > +static int rproc_assisted_recovery(struct rproc *rproc) {
> > +	const struct firmware *firmware_p;
> > +	struct device *dev = &rproc->dev;
> > +	int ret;
> > +
> > +	ret = rproc_stop(rproc, true);
> > +	if (ret)
> > +		return ret;
> > +
> > +	/* generate coredump */
> > +	rproc->ops->coredump(rproc);
> > +
> > +	/* load firmware */
> > +	ret = request_firmware(&firmware_p, rproc->firmware, dev);
> > +	if (ret < 0) {
> > +		dev_err(dev, "request_firmware failed: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	/* boot the remote processor up again */
> > +	ret = rproc_start(rproc, firmware_p);
> > +
> > +	release_firmware(firmware_p);
> > +
> > +	return ret;
> > +}
> > +
> >  /**
> >   * rproc_trigger_recovery() - recover a remoteproc
> >   * @rproc: the remote processor
> > @@ -1901,7 +1944,6 @@ static int __rproc_detach(struct rproc *rproc)
> >   */
> >  int rproc_trigger_recovery(struct rproc *rproc)  {
> > -	const struct firmware *firmware_p;
> >  	struct device *dev = &rproc->dev;
> >  	int ret;
> >
> > @@ -1915,24 +1957,10 @@ int rproc_trigger_recovery(struct rproc
> > *rproc)
> >
> >  	dev_err(dev, "recovering %s\n", rproc->name);
> >
> > -	ret = rproc_stop(rproc, true);
> > -	if (ret)
> > -		goto unlock_mutex;
> > -
> > -	/* generate coredump */
> > -	rproc->ops->coredump(rproc);
> > -
> > -	/* load firmware */
> > -	ret = request_firmware(&firmware_p, rproc->firmware, dev);
> > -	if (ret < 0) {
> > -		dev_err(dev, "request_firmware failed: %d\n", ret);
> > -		goto unlock_mutex;
> > -	}
> > -
> > -	/* boot the remote processor up again */
> > -	ret = rproc_start(rproc, firmware_p);
> > -
> > -	release_firmware(firmware_p);
> > +	if (rproc->self_recovery)
> > +		ret = rproc_self_recovery(rproc);
> 
> If some platforms have to manually reset the remote processor (without
> reloading the firmware) the name could not be relevant...
> 
> Following comments are only suggestions that needs to be commented by
> maintainers
> 
> What about rproc_attach_recovery ?

Looks better.

> 
> > +	else
> > +		ret = rproc_assisted_recovery(rproc);
> 
> and rproc_firmware_recovery ?

Yeah, better.

> 
> 
> >
> >  unlock_mutex:
> >  	mutex_unlock(&rproc->lock);
> > diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> > index e0600e1e5c17..b32ef46f8aa4 100644
> > --- a/include/linux/remoteproc.h
> > +++ b/include/linux/remoteproc.h
> > @@ -529,6 +529,7 @@ struct rproc_dump_segment {
> >   * @elf_machine: firmware ELF machine
> >   * @cdev: character device of the rproc
> >   * @cdev_put_on_release: flag to indicate if remoteproc should be
> > shutdown on @char_dev release
> > + * @self_recovery: flag to indicate if remoteproc support self
> > + recovery
> >   */
> >  struct rproc {
> >  	struct list_head node;
> > @@ -568,6 +569,7 @@ struct rproc {
> >  	u16 elf_machine;
> >  	struct cdev cdev;
> >  	bool cdev_put_on_release;
> > +	bool self_recovery;
> 
> This bool seems needed because we have lost the previous state before crash.
> I wonder if a new rproc->state such as RPROC_REBOOT could avoid this
> boolean.

REBOOT not able to differentiable self recovery or firmware recovery?
Anyway I'll check to add a BIT instead a bool.

> 
> 
> I will try to test you patch on stm32mp1 next week

Thanks,
Peng.

> 
> Regards,
> Arnaud
> 
> >  };
> >
> >  /**