delete-node without label or address from overlay dts

delete-node without label or address from overlay dts

[Phil Dawson]

Hi,

Apologies if this is covered in documentation that I've missed.
Is there a way to use /delete-node/ to remove a node with no label or
address from a plugin/overlay dts file?

I have a device tree overlay file pl.dtsi that is auto generated by
vendor tools. Unfortunately many nodes in this file are generated
wrong and the overlay fails to apply.
I've been removing the broken nodes with /delete-node/ &label; syntax
in a second dtsi file and then compiling the two together with a
wrapper dts file and the commands:
gcc -E -nostdinc -undef -D__DTS__ -x assembler-with-cpp -o pl.dts.pp
<path redacted>/pl.dts
dtc -R 8 -b 0 -p 0 -@ -H epapr -o pl.dtbo -I dts -O dtb pl.dts.pp
(These are run as part of a larger yocto build so there may be some
other work around this I'm missing!)

The auto generated pl.dtsi also has a few broken nodes without labels
or addresses like this:

/dts-v1/;
/plugin/;
&amba {
    vcap_hdmi_input_1_v_proc_ss_1 {
    <contents removed for brevity>
    };
};

I am unable to figure out the syntax to remove these nodes with
/delete-node/, should this be possible?

I've tried using the below syntax:
&amba {
    /delete-node/ vcap_hdmi_input_1_v_proc_ss_1;
};

But while dtc doesn't complain, the nodes are not removed from the
resulting dtbo.

I also can't remove using the full path as there is no root node/full
path in the generated dtsi file.

According to this discussion on an unrelated project
(https://github.com/zephyrproject-rtos/zephyr/discussions/67228)
trying to delete a node with a name and address without using the
address won't work. But in my case the node has no address.

I can work around my issue by hacking the auto generated files (while
I try to persuade the vendor to fix them!) to add a label for these
nodes and then removing them using the label. But is there a correct
way of doing this just using my separate dtsi file and dtc?

Best Regards,
Phil Dawson

Re: delete-node without label or address from overlay dts

[David Gibson]

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On Thu, Jan 15, 2026 at 12:00:13PM +0000, Phil Dawson wrote:
> Hi,
> 
> Apologies if this is covered in documentation that I've missed.
> Is there a way to use /delete-node/ to remove a node with no label or
> address from a plugin/overlay dts file?

No.  /delete-node/ has no representation within overlay files.  One of
several examples of how plugin/overlays are misleading in that they
sort of resemble dtc's older build-time overlays, but not really.

> I have a device tree overlay file pl.dtsi that is auto generated by
> vendor tools. Unfortunately many nodes in this file are generated
> wrong and the overlay fails to apply.
> I've been removing the broken nodes with /delete-node/ &label; syntax
> in a second dtsi file and then compiling the two together with a
> wrapper dts file and the commands:
> gcc -E -nostdinc -undef -D__DTS__ -x assembler-with-cpp -o pl.dts.pp
> <path redacted>/pl.dts
> dtc -R 8 -b 0 -p 0 -@ -H epapr -o pl.dtbo -I dts -O dtb pl.dts.pp
> (These are run as part of a larger yocto build so there may be some
> other work around this I'm missing!)
> 
> The auto generated pl.dtsi also has a few broken nodes without labels
> or addresses like this:
> 
> /dts-v1/;
> /plugin/;
> &amba {
>     vcap_hdmi_input_1_v_proc_ss_1 {
>     <contents removed for brevity>
>     };
> };
> 
> I am unable to figure out the syntax to remove these nodes with
> /delete-node/, should this be possible?
> 
> I've tried using the below syntax:
> &amba {
>     /delete-node/ vcap_hdmi_input_1_v_proc_ss_1;
> };
> 
> But while dtc doesn't complain, the nodes are not removed from the
> resulting dtbo.

Hm, we probably should make this generate an error.  I'm unlikely to
get to that any time soon, though.

> I also can't remove using the full path as there is no root node/full
> path in the generated dtsi file.
> 
> According to this discussion on an unrelated project
> (https://github.com/zephyrproject-rtos/zephyr/discussions/67228)
> trying to delete a node with a name and address without using the
> address won't work. But in my case the node has no address.
> 
> I can work around my issue by hacking the auto generated files (while
> I try to persuade the vendor to fix them!) to add a label for these
> nodes and then removing them using the label. But is there a correct
> way of doing this just using my separate dtsi file and dtc?
> 
> Best Regards,
> Phil Dawson
> 

-- 
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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Re: delete-node without label or address from overlay dts

[Phil Dawson]

On Fri, 16 Jan 2026 at 13:03, David Gibson <david@gibson.dropbear.id.au> wrote:
>
> On Thu, Jan 15, 2026 at 12:00:13PM +0000, Phil Dawson wrote:
> > Hi,
> >
> > Apologies if this is covered in documentation that I've missed.
> > Is there a way to use /delete-node/ to remove a node with no label or
> > address from a plugin/overlay dts file?
>
> No.  /delete-node/ has no representation within overlay files.  One of
> several examples of how plugin/overlays are misleading in that they
> sort of resemble dtc's older build-time overlays, but not really.
>
Just to be clear as my understanding is a bit muddy:

I know you cannot use an overlay to remove a node from the base tree
at runtime.

But is it correct that when constructing an overlay with dtc you can
only use /delete-node/ if the node you wish to remove has a label
or address?

> > I have a device tree overlay file pl.dtsi that is auto generated by
> > vendor tools. Unfortunately many nodes in this file are generated
> > wrong and the overlay fails to apply.
> > I've been removing the broken nodes with /delete-node/ &label; syntax
> > in a second dtsi file and then compiling the two together with a
> > wrapper dts file and the commands:
> > gcc -E -nostdinc -undef -D__DTS__ -x assembler-with-cpp -o pl.dts.pp
> > <path redacted>/pl.dts
> > dtc -R 8 -b 0 -p 0 -@ -H epapr -o pl.dtbo -I dts -O dtb pl.dts.pp
> > (These are run as part of a larger yocto build so there may be some
> > other work around this I'm missing!)
> >
> > The auto generated pl.dtsi also has a few broken nodes without labels
> > or addresses like this:
> >
> > /dts-v1/;
> > /plugin/;
> > &amba {
> >     vcap_hdmi_input_1_v_proc_ss_1 {
> > <contents removed for brevity>
> >     };
> > };
> >
> > I am unable to figure out the syntax to remove these nodes with
> > /delete-node/, should this be possible?
> >
> > I've tried using the below syntax:
> > &amba {
> >     /delete-node/ vcap_hdmi_input_1_v_proc_ss_1;
> > };
> >
> > But while dtc doesn't complain, the nodes are not removed from the
> > resulting dtbo.
>
> Hm, we probably should make this generate an error.  I'm unlikely to
> get to that any time soon, though.
>
> > I also can't remove using the full path as there is no root node/full
> > path in the generated dtsi file.
> >
> > According to this discussion on an unrelated project
> > (https://github.com/zephyrproject-rtos/zephyr/discussions/67228)
> > trying to delete a node with a name and address without using the
> > address won't work. But in my case the node has no address.
> >
> > I can work around my issue by hacking the auto generated files (while
> > I try to persuade the vendor to fix them!) to add a label for these
> > nodes and then removing them using the label. But is there a correct
> > way of doing this just using my separate dtsi file and dtc?
> >
> > Best Regards,
> > Phil Dawson
> >
>
> --
> 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

Thanks,
Phil

Re: delete-node without label or address from overlay dts

[David Gibson]

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On Fri, Jan 16, 2026 at 02:39:30PM +0000, Phil Dawson wrote:
> On Fri, 16 Jan 2026 at 13:03, David Gibson <david@gibson.dropbear.id.au> wrote:
> >
> > On Thu, Jan 15, 2026 at 12:00:13PM +0000, Phil Dawson wrote:
> > > Hi,
> > >
> > > Apologies if this is covered in documentation that I've missed.
> > > Is there a way to use /delete-node/ to remove a node with no label or
> > > address from a plugin/overlay dts file?
> >
> > No.  /delete-node/ has no representation within overlay files.  One of
> > several examples of how plugin/overlays are misleading in that they
> > sort of resemble dtc's older build-time overlays, but not really.
> >
> Just to be clear as my understanding is a bit muddy:
> 
> I know you cannot use an overlay to remove a node from the base tree
> at runtime.

Oh, sorry, I misunderstood your question.

> But is it correct that when constructing an overlay with dtc you can
> only use /delete-node/ if the node you wish to remove has a label
> or address?

I think that's correct, though kind of by accident.

> > > I have a device tree overlay file pl.dtsi that is auto generated by
> > > vendor tools. Unfortunately many nodes in this file are generated
> > > wrong and the overlay fails to apply.
> > > I've been removing the broken nodes with /delete-node/ &label; syntax
> > > in a second dtsi file and then compiling the two together with a
> > > wrapper dts file and the commands:
> > > gcc -E -nostdinc -undef -D__DTS__ -x assembler-with-cpp -o pl.dts.pp
> > > <path redacted>/pl.dts
> > > dtc -R 8 -b 0 -p 0 -@ -H epapr -o pl.dtbo -I dts -O dtb pl.dts.pp
> > > (These are run as part of a larger yocto build so there may be some
> > > other work around this I'm missing!)
> > >
> > > The auto generated pl.dtsi also has a few broken nodes without labels
> > > or addresses like this:
> > >
> > > /dts-v1/;
> > > /plugin/;
> > > &amba {
> > >     vcap_hdmi_input_1_v_proc_ss_1 {
> > > <contents removed for brevity>
> > >     };
> > > };
> > >
> > > I am unable to figure out the syntax to remove these nodes with
> > > /delete-node/, should this be possible?
> > >
> > > I've tried using the below syntax:
> > > &amba {
> > >     /delete-node/ vcap_hdmi_input_1_v_proc_ss_1;
> > > };
> > >
> > > But while dtc doesn't complain, the nodes are not removed from the
> > > resulting dtbo.

Right.  So this happens because when compiling a plugin each top-level
chunk is compiled into a separate "fragment" in the plugin.  The
/delete-node/ here would remove anything already defined in the same
fragment, but not things in earlier fragments.

In non-/plugin/ mode we merge all the chunks together, so
/delete-node/ (and /delete-property/ for that matter) will apply
properly regardless of which chunks everything appears in.

This is another ugly consequence of the rather haphazard ways
plugins/overlays are designed / implemented.  I think we could fix it
by not merging everything during the parse: instead generating a list
of chunks, then merging them in a later, explicit step.  We'd always
do that for full trees, and merge only those pieces that we can
resolve for plugins.

I think that would be a good fix, but I'm certainly not going to have
time to implement it in the forseeable future.

> > Hm, we probably should make this generate an error.  I'm unlikely to
> > get to that any time soon, though.
> >
> > > I also can't remove using the full path as there is no root node/full
> > > path in the generated dtsi file.
> > >
> > > According to this discussion on an unrelated project
> > > (https://github.com/zephyrproject-rtos/zephyr/discussions/67228)
> > > trying to delete a node with a name and address without using the
> > > address won't work. But in my case the node has no address.
> > >
> > > I can work around my issue by hacking the auto generated files (while
> > > I try to persuade the vendor to fix them!) to add a label for these
> > > nodes and then removing them using the label. But is there a correct
> > > way of doing this just using my separate dtsi file and dtc?
> > >
> > > Best Regards,
> > > Phil Dawson
> > >
> >
> > --
> > 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
> 
> Thanks,
> Phil
> 

-- 
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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Re: delete-node without label or address from overlay dts

[Phil Dawson]

On Tue, 20 Jan 2026 at 04:53, David Gibson <david@gibson.dropbear.id.au> wrote:
>
> On Fri, Jan 16, 2026 at 02:39:30PM +0000, Phil Dawson wrote:
> > On Fri, 16 Jan 2026 at 13:03, David Gibson <david@gibson.dropbear.id.au> wrote:
> > >
> > > On Thu, Jan 15, 2026 at 12:00:13PM +0000, Phil Dawson wrote:
> > > > Hi,
> > > >
> > > > Apologies if this is covered in documentation that I've missed.
> > > > Is there a way to use /delete-node/ to remove a node with no label or
> > > > address from a plugin/overlay dts file?
> > >
> > > No.  /delete-node/ has no representation within overlay files.  One of
> > > several examples of how plugin/overlays are misleading in that they
> > > sort of resemble dtc's older build-time overlays, but not really.
> > >
> > Just to be clear as my understanding is a bit muddy:
> >
> > I know you cannot use an overlay to remove a node from the base tree
> > at runtime.
>
> Oh, sorry, I misunderstood your question.
>
> > But is it correct that when constructing an overlay with dtc you can
> > only use /delete-node/ if the node you wish to remove has a label
> > or address?
>
> I think that's correct, though kind of by accident.
>
> > > > I have a device tree overlay file pl.dtsi that is auto generated by
> > > > vendor tools. Unfortunately many nodes in this file are generated
> > > > wrong and the overlay fails to apply.
> > > > I've been removing the broken nodes with /delete-node/ &label; syntax
> > > > in a second dtsi file and then compiling the two together with a
> > > > wrapper dts file and the commands:
> > > > gcc -E -nostdinc -undef -D__DTS__ -x assembler-with-cpp -o pl.dts.pp
> > > > <path redacted>/pl.dts
> > > > dtc -R 8 -b 0 -p 0 -@ -H epapr -o pl.dtbo -I dts -O dtb pl.dts.pp
> > > > (These are run as part of a larger yocto build so there may be some
> > > > other work around this I'm missing!)
> > > >
> > > > The auto generated pl.dtsi also has a few broken nodes without labels
> > > > or addresses like this:
> > > >
> > > > /dts-v1/;
> > > > /plugin/;
> > > > &amba {
> > > >     vcap_hdmi_input_1_v_proc_ss_1 {
> > > > <contents removed for brevity>
> > > >     };
> > > > };
> > > >
> > > > I am unable to figure out the syntax to remove these nodes with
> > > > /delete-node/, should this be possible?
> > > >
> > > > I've tried using the below syntax:
> > > > &amba {
> > > >     /delete-node/ vcap_hdmi_input_1_v_proc_ss_1;
> > > > };
> > > >
> > > > But while dtc doesn't complain, the nodes are not removed from the
> > > > resulting dtbo.
>
> Right.  So this happens because when compiling a plugin each top-level
> chunk is compiled into a separate "fragment" in the plugin.  The
> /delete-node/ here would remove anything already defined in the same
> fragment, but not things in earlier fragments.
>
> In non-/plugin/ mode we merge all the chunks together, so
> /delete-node/ (and /delete-property/ for that matter) will apply
> properly regardless of which chunks everything appears in.
>
> This is another ugly consequence of the rather haphazard ways
> plugins/overlays are designed / implemented.  I think we could fix it
> by not merging everything during the parse: instead generating a list
> of chunks, then merging them in a later, explicit step.  We'd always
> do that for full trees, and merge only those pieces that we can
> resolve for plugins.
>
> I think that would be a good fix, but I'm certainly not going to have
> time to implement it in the forseeable future.

I agree this sounds like a good fix but obviously time constraints are
always hard!

I've worked around my issue by scripting a process to add labels to
the nodes without them and then removing them at compile time
with /delete-node/.

Thank you for your help.
>
> > > Hm, we probably should make this generate an error.  I'm unlikely to
> > > get to that any time soon, though.
> > >
> > > > I also can't remove using the full path as there is no root node/full
> > > > path in the generated dtsi file.
> > > >
> > > > According to this discussion on an unrelated project
> > > > (https://github.com/zephyrproject-rtos/zephyr/discussions/67228)
> > > > trying to delete a node with a name and address without using the
> > > > address won't work. But in my case the node has no address.
> > > >
> > > > I can work around my issue by hacking the auto generated files (while
> > > > I try to persuade the vendor to fix them!) to add a label for these
> > > > nodes and then removing them using the label. But is there a correct
> > > > way of doing this just using my separate dtsi file and dtc?
> > > >
> > > > Best Regards,
> > > > Phil Dawson
> > > >
> > >
> > > --
> > > 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
> >
> > Thanks,
> > Phil
> >
>
> --
> 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