linux-kernel - Re: How delete node or property in overlayd dts?

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Message-ID: <78f06f2d-7561-dde9-c155-9f1612f9067a@gmail.com>
Date:   Sat, 18 Aug 2018 18:38:44 +0800
From:   Zhang Bo <zbsdta@...il.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: How delete node or property in overlayd dts?


在 2018/8/18 1:47, Rob Herring 写道:
> On Tue, Aug 14, 2018 at 7:26 PM Frank Rowand <frowand.list@...il.com> wrote:
>> On 08/14/18 07:46, 张波 wrote:
>>> /delete-node/ /delete-prop/ could be used in dtsi files without device
>>> tree overlay.
>>>
>>> but with device tree overlay,  /delete-node/ and  /delete-prop/ are not work.
>>> How to delete property and node in overlay dts?
>>>
>>> for example,
>>> in basel.dts have following node
>>> node1 {
>>>      property1;
>>>      property3;
>>>      node2 {
>>>          property2;
>>>      }
>>> }
>>>
>>> in overlay.dts as following
>>>   node1 {
>>>      /delete-property/ property1;
>>>      /delete-node/ node2;
>>> }
>>>
>>> after overlay, property1 and node2 is not deleted.
>>>
>> The /delete-node/ and /delete-prop/ directives are only used by the
>> dtc compiler within a single compilation.
>>
>> There is nothing in the format of a devicetree blob to represent the
>> notion of deleting a property or a node.
>>
>> You can not delete a property or a node in an overlay dtb.
> Though you can add/override 'status' with 'status = "disabled";' which
> should be treated very similar to a node not being present. I say
> similar because it's a source of bugs for the OS to fail to pay
> attention to status property.

there is document in 
https://android.googlesource.com/kernel/msm/+/android-7.0.0_r0.11/Documentation/devicetree/overlay-notes.txt,

In above document, remove node or property by adding - operator before 
node or property. but I didn't find it in released kernel source code, 
Is there any update plan about this problem?

{

     property-a;       /* add property-a to the target */

     -proptery-b;     /* remove property-b from the target */

     -node-b {          /* remove an exiting node-b */

         ...

     }

}