Re: [PATCH v5 07/19] remoteproc: Add new get_loaded_rsc_table() to rproc_ops

[Arnaud POULIQUEN]

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@xxxxxxxxxx>
> ---
> 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.

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.
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.

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.

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);
>