Re: [PATCH v2 3/6] of_reserved_mem: add a helper for rmem device_init op

[Maxime Ripard]

On Tue, Mar 03, 2026 at 01:33:46PM +0100, Albert Esteve wrote:
> Add a helper function wrapping internal reserved memory
> device_init call and expose it externally.
> 
> Use the new helper function within of_reserved_mem_device_init_by_idx().
> 
> Signed-off-by: Albert Esteve <aesteve@xxxxxxxxxx>
> ---
>  drivers/of/of_reserved_mem.c    | 27 +++++++++++++++++++++++----
>  include/linux/of_reserved_mem.h |  8 ++++++++
>  2 files changed, 31 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 1fd28f8056108..3a350bef8f11e 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -605,6 +605,28 @@ struct rmem_assigned_device {
>  static LIST_HEAD(of_rmem_assigned_device_list);
>  static DEFINE_MUTEX(of_rmem_assigned_device_mutex);
>  
> +/**
> + * of_reserved_mem_device_init_with_mem() - assign reserved memory region to
> + *					    given device
> + * @dev:	Pointer to the device to configure
> + * @rmem:	Reserved memory region to assign
> + *
> + * This function assigns respective DMA-mapping operations based on the
> + * reserved memory region already provided in @rmem to the @dev device,
> + * without walking DT nodes.
> + *
> + * Returns error code or zero on success.
> + */
> +int of_reserved_mem_device_init_with_mem(struct device *dev,
> +					 struct reserved_mem *rmem)
> +{
> +	if (!dev || !rmem || !rmem->ops || !rmem->ops->device_init)
> +		return -EINVAL;
> +
> +	return rmem->ops->device_init(rmem, dev);
> +}
> +EXPORT_SYMBOL_GPL(of_reserved_mem_device_init_with_mem);
> +
>  /**
>   * of_reserved_mem_device_init_by_idx() - assign reserved memory region to
>   *					  given device
> @@ -643,14 +665,11 @@ int of_reserved_mem_device_init_by_idx(struct device *dev,
>  	rmem = of_reserved_mem_lookup(target);
>  	of_node_put(target);
>  
> -	if (!rmem || !rmem->ops || !rmem->ops->device_init)
> -		return -EINVAL;
> -
>  	rd = kmalloc_obj(struct rmem_assigned_device);
>  	if (!rd)
>  		return -ENOMEM;
>  
> -	ret = rmem->ops->device_init(rmem, dev);
> +	ret = of_reserved_mem_device_init_with_mem(dev, rmem);
>  	if (ret == 0) {
>  		rd->dev = dev;
>  		rd->rmem = rmem;

I think you need to take the allocation of rd, and everything below.
Otherwise, your device, despite being attechd, wouldn't be listed
anywhere.

Maxime

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