linux-kernel - Re: [RFC PATCH 09/77] dtc: Introduce mark_local

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Message-ID: <aWg5bD4zWYAQOYai@zatzit>
Date: Thu, 15 Jan 2026 11:48:44 +1100
From: David Gibson <david@...son.dropbear.id.au>
To: Herve Codina <herve.codina@...tlin.com>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Ayush Singh <ayush@...gleboard.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	devicetree-compiler@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree-spec@...r.kernel.org,
	Hui Pu <hui.pu@...ealthcare.com>,
	Ian Ray <ian.ray@...ealthcare.com>,
	Luca Ceresoli <luca.ceresoli@...tlin.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [RFC PATCH 09/77] dtc: Introduce mark_local_phandles()

On Mon, Jan 12, 2026 at 03:18:59PM +0100, Herve Codina wrote:
> In order to have the new FDT_REF_LOCAL tag present in a dtb, the phandle
> reference needs to be identify as a local reference.
> 
> This is the purpose of mark_local_phandles().
> 
> It identifies a phandle reference as a local reference when this
> reference points to a local node.
> 
> With that node, the related FDT_REF_LOCAL tag is set in the dtb.

I dislike caching redundant information (whether the ref is local) -
it's an opportunity for them to get out of sync and cause bugs.  Is
there a strong case that you can't just determine whether it's local
only when you actually go to use it?

> 
> Signed-off-by: Herve Codina <herve.codina@...tlin.com>
> ---
>  dtc.c      |  1 +
>  dtc.h      |  1 +
>  livetree.c | 26 ++++++++++++++++++++++++++
>  3 files changed, 28 insertions(+)
> 
> diff --git a/dtc.c b/dtc.c
> index 88f03ff..d0b4de3 100644
> --- a/dtc.c
> +++ b/dtc.c
> @@ -334,6 +334,7 @@ int main(int argc, char *argv[])
>  	}
>  
>  	update_phandles_ref(dti);
> +	mark_local_phandles(dti);
>  
>  	process_checks(force, dti);
>  
> diff --git a/dtc.h b/dtc.h
> index 351fe41..08c9f07 100644
> --- a/dtc.h
> +++ b/dtc.h
> @@ -346,6 +346,7 @@ void generate_fixups_tree(struct dt_info *dti, const char *name);
>  void generate_local_fixups_tree(struct dt_info *dti, const char *name);
>  
>  void update_phandles_ref(struct dt_info *dti);
> +void mark_local_phandles(struct dt_info *dti);
>  
>  /* Checks */
>  
> diff --git a/livetree.c b/livetree.c
> index 9e30a63..2a0a7ed 100644
> --- a/livetree.c
> +++ b/livetree.c
> @@ -1196,3 +1196,29 @@ void update_phandles_ref(struct dt_info *dti)
>  {
>  	update_phandles_ref_internal(dti, dti->dt);
>  }
> +
> +static void mark_local_phandles_internal(struct dt_info *dti,
> +					 struct node *node)
> +{
> +	struct node *c;
> +	struct property *prop;
> +	struct marker *m;
> +	struct node *refnode;
> +
> +	for_each_property(node, prop) {
> +		m = prop->val.markers;
> +		for_each_marker_of_type(m, REF_PHANDLE) {
> +			refnode = get_node_by_ref(dti->dt, m->ref);
> +			if (refnode)
> +				m->is_local = true;
> +		}
> +	}
> +
> +	for_each_child(node, c)
> +		mark_local_phandles_internal(dti, c);
> +}
> +
> +void mark_local_phandles(struct dt_info *dti)
> +{
> +	mark_local_phandles_internal(dti, dti->dt);
> +}
> -- 
> 2.52.0
> 
> 

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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