Re: [PATCH 04/18] of: partition: support of_partition_ensure_probed on parent device

[Marco Felsch <m.felsch@pengutronix.de>]

Hi Ahmad,

On 23-05-31, Ahmad Fatoum wrote:
> barebox-state code uses of_partition_ensure_probed to resolve the
> backend property. We want to allow backend to point directly at a
> storage device instead of a partition. We can't determine whether a DT
> device is a storage device though before it's probed, so let's have
> of_partition_ensure_probed support either case.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  drivers/of/partition.c | 26 ++++++++++++++++++++++----
>  drivers/of/platform.c  |  2 +-
>  2 files changed, 23 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/of/partition.c b/drivers/of/partition.c
> index 40c47f554ad2..a70e503cec9e 100644
> --- a/drivers/of/partition.c
> +++ b/drivers/of/partition.c
> @@ -110,14 +110,32 @@ int of_parse_partitions(struct cdev *cdev, struct device_node *node)
>  	return 0;
>  }
>  
> +/**
> + * of_partition_ensure_probed - ensure a parition is probed
> + * @np: pointer to a partition or to a partitionable device
> + *      Unfortunately, there is no completely reliable way
> + *      to differentiate partitions from devices prior to
> + *      probing, because partitions may also have compatibles.
> + *      We only handle nvmem-cells, so anything besides that
> + *      is assumed to be a device that should be probed directly.
> + *
> + * Returns zero on success or a negative error code otherwise
> + */
>  int of_partition_ensure_probed(struct device_node *np)
>  {
> -	np = of_get_parent(np);
> +	struct device_node *parent = of_get_parent(np);
>  
> -	if (of_device_is_compatible(np, "fixed-partitions"))
> -		np = of_get_parent(np);
> +	if (parent && of_device_is_compatible(parent, "fixed-partitions"))

When is the parent not present? This should only be the case when 'np'
points to the root_node. So in case of !parent I would return -EINVAL
early.

> +		return of_device_ensure_probed(of_get_parent(np));
							     ^
							   parent?

Not related to this patch but the logic would become easier if would
have devices for each mtd-part, like the kernel does. In such case we
could avoid these special handlings and just use
of_device_ensure_probed() at least for the mtd-parts, nvmem-cells still
need a special handling.

Regards,
  Marco

> -	return np ? of_device_ensure_probed(np) : -EINVAL;
> +	if (of_get_compatible_child(np, "fixed-partitions"))
> +		return of_device_ensure_probed(np);
> +
> +	if (!of_property_present(np, "compatible") ||
> +	    of_device_is_compatible(np, "nvmem-cells"))
> +		return of_device_ensure_probed(parent);
> +
> +	return of_device_ensure_probed(np);
>  }
>  EXPORT_SYMBOL_GPL(of_partition_ensure_probed);
>  
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index ab737629325a..78b8a31331db 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -484,7 +484,7 @@ int of_device_ensure_probed(struct device_node *np)
>  {
>  	struct device *dev;
>  
> -	if (!deep_probe_is_supported())
> +	if (!np || !deep_probe_is_supported())
>  		return 0;
>  
>  	dev = of_device_create_on_demand(np);
> -- 
> 2.39.2
> 
> 
>