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Date:   Wed, 17 Feb 2021 14:22:51 -0700
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     Arnaud POULIQUEN <arnaud.pouliquen@foss.st.com>
Cc:     ohad@wizery.com, bjorn.andersson@linaro.org,
        arnaud.pouliquen@st.com, robh+dt@kernel.org,
        mcoquelin.stm32@gmail.com, alexandre.torgue@st.com,
        linux-remoteproc@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v5 07/19] remoteproc: Add new get_loaded_rsc_table() to
 rproc_ops
Message-ID: <20210217212251.GA2800385@xps15>
References: <20210211234627.2669674-1-mathieu.poirier@linaro.org>
 <20210211234627.2669674-8-mathieu.poirier@linaro.org>
 <406fe414-f454-c91d-8bbd-ce323a9612e7@foss.st.com>
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On Mon, Feb 15, 2021 at 02:10:10PM +0100, Arnaud POULIQUEN wrote:
> Hi Mathieu,
> 
> On 2/12/21 12:46 AM, Mathieu Poirier wrote:
> > Add a new get_loaded_rsc_table() operation in order to support
> > scenarios where the remoteproc core has booted a remote processor
> > and detaches from it.  When re-attaching to the remote processor,
> > the core needs to know where the resource table has been placed
> > in memory.
> > 
> > Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> > ---
> > New for V5:
> > - Added function rproc_set_loaded_rsc_table() to keep rproc_attach() clean.
> > - Setting ->cached_table, ->table_ptr and ->table_sz in the remoteproc core
> >   rather than the platform drivers.
> > ---
> >  drivers/remoteproc/remoteproc_core.c     | 35 ++++++++++++++++++++++++
> >  drivers/remoteproc/remoteproc_internal.h | 10 +++++++
> >  include/linux/remoteproc.h               |  6 +++-
> >  3 files changed, 50 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> > index e6606d10a4c8..741bc20de437 100644
> > --- a/drivers/remoteproc/remoteproc_core.c
> > +++ b/drivers/remoteproc/remoteproc_core.c
> > @@ -1537,6 +1537,35 @@ static int rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
> >  	return ret;
> >  }
> >  
> > +static int rproc_set_loaded_rsc_table(struct rproc *rproc)
> > +{
> > +	struct resource_table *table_ptr;
> > +	struct device *dev = &rproc->dev;
> > +	size_t table_sz;
> > +	int ret;
> > +
> > +	table_ptr = rproc_get_loaded_rsc_table(rproc, &table_sz);
> > +	if (IS_ERR_OR_NULL(table_ptr)) {
> > +		if (!table_ptr)
> > +			ret = -EINVAL;
> 
> I did few tests on this showing that this approach does not cover all use cases.
> 
> The first one is a firmware without resource table. In this case table_ptr
> should be null, or we have to consider the -ENOENT error as a non error usecase.
>

Right, I'll provision for those cases.
 
> The second one, more tricky, is a firmware started by the remoteproc framework.
> In this case the resource table address is retrieved from the ELF file by the
> core part.

Correct.

> So if we detach and reattach rproc_get_loaded_rsc_table cannot return the
> address. Look to me that we should have also an alocation of the clean_table in
> rproc_start and then to keep the memory allocated until a shutdown.

I assumed the address of the resource table found in the ELF image was the same
as the one known by the platform driver.  In hindsight I realise the platform
driver may not know that address.

> 
> That said regarding the complexity to re-attach, I wonder if it would not be
> better to focus first on a simple detach, and address the reattachment in a
> separate series, to move forward in stages.

I agree that OFFLINE -> RUNNING -> DETACHED -> ATTACHED is introducing some
complexity related to the management of the resource table that where not
expected.  We could concentrate on a simple detach and see where that takes us.
It would also mean to get rid of the "autonomous-on-core-shutdown" DT binding. 

Thanks,
Mathieu

> 
> Regards,
> Arnaud
> 
> > +		else
> > +			ret = PTR_ERR(table_ptr);
> > +
> > +		dev_err(dev, "can't load resource table: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	/*
> > +	 * The resource table is already loaded in device memory, no need
> > +	 * to work with a cached table.
> > +	 */
> > +	rproc->cached_table = NULL;
> > +	rproc->table_ptr = table_ptr;
> > +	rproc->table_sz = table_sz;
> > +
> > +	return 0;
> > +}
> > +
> >  /*
> >   * Attach to remote processor - similar to rproc_fw_boot() but without
> >   * the steps that deal with the firmware image.
> > @@ -1556,6 +1585,12 @@ static int rproc_attach(struct rproc *rproc)
> >  		return ret;
> >  	}
> >  
> > +	ret = rproc_set_loaded_rsc_table(rproc);
> > +	if (ret) {
> > +		dev_err(dev, "can't load resource table: %d\n", ret);
> > +		goto disable_iommu;
> > +	}
> > +
> >  	/* reset max_notifyid */
> >  	rproc->max_notifyid = -1;
> >  
> > diff --git a/drivers/remoteproc/remoteproc_internal.h b/drivers/remoteproc/remoteproc_internal.h
> > index c34002888d2c..4f73aac7e60d 100644
> > --- a/drivers/remoteproc/remoteproc_internal.h
> > +++ b/drivers/remoteproc/remoteproc_internal.h
> > @@ -177,6 +177,16 @@ struct resource_table *rproc_find_loaded_rsc_table(struct rproc *rproc,
> >  	return NULL;
> >  }
> >  
> > +static inline
> > +struct resource_table *rproc_get_loaded_rsc_table(struct rproc *rproc,
> > +						  size_t *size)
> > +{
> > +	if (rproc->ops->get_loaded_rsc_table)
> > +		return rproc->ops->get_loaded_rsc_table(rproc, size);
> > +
> > +	return NULL;
> > +}
> > +
> >  static inline
> >  bool rproc_u64_fit_in_size_t(u64 val)
> >  {
> > diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> > index 6b0a0ed30a03..51538a7d120d 100644
> > --- a/include/linux/remoteproc.h
> > +++ b/include/linux/remoteproc.h
> > @@ -368,7 +368,9 @@ enum rsc_handling_status {
> >   * RSC_HANDLED if resource was handled, RSC_IGNORED if not handled and a
> >   * negative value on error
> >   * @load_rsc_table:	load resource table from firmware image
> > - * @find_loaded_rsc_table: find the loaded resouce table
> > + * @find_loaded_rsc_table: find the loaded resource table from firmware image
> > + * @get_loaded_rsc_table: get resource table installed in memory
> > + *			  by external entity
> >   * @load:		load firmware to memory, where the remote processor
> >   *			expects to find it
> >   * @sanity_check:	sanity check the fw image
> > @@ -390,6 +392,8 @@ struct rproc_ops {
> >  			  int offset, int avail);
> >  	struct resource_table *(*find_loaded_rsc_table)(
> >  				struct rproc *rproc, const struct firmware *fw);
> > +	struct resource_table *(*get_loaded_rsc_table)(
> > +				struct rproc *rproc, size_t *size);
> >  	int (*load)(struct rproc *rproc, const struct firmware *fw);
> >  	int (*sanity_check)(struct rproc *rproc, const struct firmware *fw);
> >  	u64 (*get_boot_addr)(struct rproc *rproc, const struct firmware *fw);
> >