Re: [Xen-devel] [PATCH v4 1/7] xen/arm: extend device_tree_for_each_node

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

On 06/08/2019 22:49, Stefano Stabellini wrote:
> Add new parameters to device_tree_for_each_node: node, depth,
> address_cells, size_cells.
address_cells (resp. size_cells) are named address_cells_p (resp. size_cells_p) 
in the code.
But I am not convinced you need them. Per the DT spec (v0.2 section 2.3.5), the 
parent should either contain the #address-cells and #size-cells or default 
values (resp. 2 and 1) will be used. It is clearly stated that values are not 
inherited from the ancestors.
So technically the implementation of device_tree_for_each_node() is incorrect. 
If you follow the spec here, then the address_cells_p and size_cells_p would 
become unnecessary.
> Node is the parent node to start the search from;
> depth is the min depth of the search (the depth of the parent node);
> address_cells and size_cells are the respective parameters at the parent
> node. Passing 0, 0, 0, 0 triggers the old behavior. >
> We need this change because in follow-up patches we want to be able to
> use reuse device_tree_for_each_node to call a function for each children
> nodes of a provided node.
>
> Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
> ---
> Changes in v4:
> - add address_cells and size_cells parameters
>
> Changes in v3:
> - improve commit message
> - improve in-code comments
> - improve code style
>
> Changes in v2:
> - new
> ---
>   xen/arch/arm/acpi/boot.c      |  2 +-
>   xen/arch/arm/bootfdt.c        | 21 +++++++++++++++------
>   xen/include/xen/device_tree.h |  6 ++++--
>   3 files changed, 20 insertions(+), 9 deletions(-)
>
> diff --git a/xen/arch/arm/acpi/boot.c b/xen/arch/arm/acpi/boot.c
> index 9b29769a10..d275f8c535 100644
> --- a/xen/arch/arm/acpi/boot.c
> +++ b/xen/arch/arm/acpi/boot.c
> @@ -248,7 +248,7 @@ int __init acpi_boot_table_init(void)
>        */
>       if ( param_acpi_off || ( !param_acpi_force
>                                && 
> device_tree_for_each_node(device_tree_flattened,
> -                                                   dt_scan_depth1_nodes, 
> NULL)))
> +                                 0, 0, 0, 0, dt_scan_depth1_nodes, NULL)))
NIT: Can we split the if?

Cheers,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel