Re: [PATCH v8 4/9] nvmem: layouts: Support fixed-layout as the nvmem device node itself

On Fri, 3 Jul 2026 15:45:17 +0200, Loic Poulain
<[email protected]> said:
> of_nvmem_layout_get_container() only looks for a child node named
> "nvmem-layout" to locate the cell definitions. This does not cover
> providers whose device tree node is itself the fixed-layout container,
> such as an eMMC boot partition block device whose fwnode points directly
> at a "fixed-layout" compatible partitions node.
>
> When no "nvmem-layout" child is present, fall back to returning the nvmem
> device node itself if it is compatible with "fixed-layout", so that its
> cells are parsed by nvmem_add_cells_from_fixed_layout().
>
> Signed-off-by: Loic Poulain <[email protected]>
> ---
>  drivers/nvmem/layouts.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvmem/layouts.c b/drivers/nvmem/layouts.c
> index b90584e1b99eab4217cbe7ec48373e18a7caf0dc..efa631ce7283bdd6c8ecda75915911b5e3a33c99 100644
> --- a/drivers/nvmem/layouts.c
> +++ b/drivers/nvmem/layouts.c
> @@ -167,7 +167,18 @@ static int nvmem_layout_bus_populate(struct nvmem_device *nvmem,
>
>  struct device_node *of_nvmem_layout_get_container(struct nvmem_device *nvmem)
>  {
> -	return of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");
> +	struct device_node *np;
> +
> +	/* Search for nvmem-layout child */
> +	np = of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");
> +	if (np)
> +		return np;
> +
> +	/* The nvmem of_node is itself a fixed-layout node */
> +	if (of_device_is_compatible(nvmem->dev.of_node, "fixed-layout"))
> +		return of_node_get(nvmem->dev.of_node);
> +
> +	return NULL;
>  }
>  EXPORT_SYMBOL_GPL(of_nvmem_layout_get_container);
>
>
> --
> 2.34.1
>
>

I have it on my TODO list to convert nvmem layouts to be fwnode-agnostic. While
I'm not sure when I'll have the time to look into it, I think it makes sense
to not introduce any new OF-specific interfaces. Can you make it into:

  struct fwnode_handle *nvmem_layout_get_container_node(struct
nvmem_device *nvmem);

by replacing of_get_child_by_name() with fwnode_get_name_child_node() and
of_device_is_compatible() with device_is_compatible()? That would mean less
churn in the future.

Other than that, it looks good.

Bart