Re: [PATCH 07/13] remoteproc: Introduce function rproc_detach()

From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: Peng Fan <peng.fan@nxp.com>
Cc: "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
	"ohad@wizery.com" <ohad@wizery.com>,
	"linux-remoteproc@vger.kernel.org"
	<linux-remoteproc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 07/13] remoteproc: Introduce function rproc_detach()
Date: Thu, 22 Oct 2020 15:55:42 -0600	[thread overview]
Message-ID: <20201022215542.GB729430@xps15> (raw)
In-Reply-To: <DB6PR0402MB2760F33EF3C3BF69D737899688020@DB6PR0402MB2760.eurprd04.prod.outlook.com>

On Thu, Oct 15, 2020 at 01:52:16AM +0000, Peng Fan wrote:
> > Subject: [PATCH 07/13] remoteproc: Introduce function rproc_detach()
> > 
> > Introduce function rproc_detach() to enable the remoteproc core to release
> > the resources associated with a remote processor without stopping its
> > operation.
> > 
> > Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> > ---
> >  drivers/remoteproc/remoteproc_core.c | 65
> > +++++++++++++++++++++++++++-
> >  include/linux/remoteproc.h           |  1 +
> >  2 files changed, 65 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/remoteproc/remoteproc_core.c
> > b/drivers/remoteproc/remoteproc_core.c
> > index 7a1fc7e0620f..f3943a1e2754 100644
> > --- a/drivers/remoteproc/remoteproc_core.c
> > +++ b/drivers/remoteproc/remoteproc_core.c
> > @@ -1644,7 +1644,7 @@ static int rproc_stop(struct rproc *rproc, bool
> > crashed)
> >  /*
> >   * __rproc_detach(): Does the opposite of rproc_attach()
> >   */
> > -static int __maybe_unused __rproc_detach(struct rproc *rproc)
> > +static int __rproc_detach(struct rproc *rproc)
> >  {
> >  	struct device *dev = &rproc->dev;
> >  	int ret;
> > @@ -1887,6 +1887,69 @@ void rproc_shutdown(struct rproc *rproc)  }
> > EXPORT_SYMBOL(rproc_shutdown);
> > 
> > +/**
> > + * rproc_detach() - Detach the remote processor from the
> > + * remoteproc core
> > + *
> > + * @rproc: the remote processor
> > + *
> > + * Detach a remote processor (previously attached to with rproc_actuate()).
> > + *
> > + * In case @rproc is still being used by an additional user(s), then
> > + * this function will just decrement the power refcount and exit,
> > + * without disconnecting the device.
> > + *
> > + * Function rproc_detach() calls __rproc_detach() in order to let a
> > +remote
> > + * processor know that services provided by the application processor
> > +are
> > + * no longer available.  From there it should be possible to remove the
> > + * platform driver and even power cycle the application processor (if
> > +the HW
> > + * supports it) without needing to switch off the remote processor.
> > + */
> > +int rproc_detach(struct rproc *rproc)
> > +{
> > +	struct device *dev = &rproc->dev;
> > +	int ret;
> > +
> > +	ret = mutex_lock_interruptible(&rproc->lock);
> > +	if (ret) {
> > +		dev_err(dev, "can't lock rproc %s: %d\n", rproc->name, ret);
> > +		return ret;
> > +	}
> > +
> > +	if (rproc->state != RPROC_RUNNING && rproc->state !=
> > RPROC_ATTACHED) {
> > +		ret = -EPERM;
> > +		goto out;
> > +	}
> > +
> > +	/* if the remote proc is still needed, bail out */
> > +	if (!atomic_dec_and_test(&rproc->power)) {
> > +		ret = -EBUSY;
> > +		goto out;
> > +	}
> > +
> > +	ret = __rproc_detach(rproc);
> > +	if (ret) {
> > +		atomic_inc(&rproc->power);
> > +		goto out;
> > +	}
> > +
> > +	/* clean up all acquired resources */
> > +	rproc_resource_cleanup(rproc);
> > +
> > +	rproc_disable_iommu(rproc);
> > +
> > +	/*
> > +	 * Set the remote processor's table pointer to NULL.  Since mapping
> > +	 * of the resource table to a virtual address is done in the platform
> > +	 * driver, unmapping should also be done there.
> > +	 */
> > +	rproc->table_ptr = NULL;
> > +out:
> > +	mutex_unlock(&rproc->lock);
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL(rproc_detach);
> > +
> >  /**
> >   * rproc_get_by_phandle() - find a remote processor by phandle
> >   * @phandle: phandle to the rproc
> > diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h index
> > 1a57e165da2c..6250491ee851 100644
> > --- a/include/linux/remoteproc.h
> > +++ b/include/linux/remoteproc.h
> > @@ -656,6 +656,7 @@ rproc_of_resm_mem_entry_init(struct device *dev,
> > u32 of_resm_idx, size_t len,
> > 
> >  int rproc_boot(struct rproc *rproc);
> >  void rproc_shutdown(struct rproc *rproc);
> > +int rproc_detach(struct rproc *rproc);
> >  void rproc_report_crash(struct rproc *rproc, enum rproc_crash_type type);
> > int rproc_coredump_add_segment(struct rproc *rproc, dma_addr_t da, size_t
> > size);  int rproc_coredump_add_custom_segment(struct rproc *rproc,
> > --
> 
> 
> Reviewed-by: Peng Fan <peng.fan@nxp.com>
> 
> Not relevant to your patch, just see unregister_virtio_device not set device
> status when reading code, should that add device status setting in
> unregister_virtio_device?

I must admit that I don't understand the question - would you mind rephrasing or
expanding?

Thanks,
Mathieu

> 
> 