[PATCH net-next 09/13] dt-bindings: net: airoha: Add airoha,npu phandle property

[Conor Dooley]

On Wed, Feb 05, 2025 at 09:54:43PM +0100, Lorenzo Bianconi wrote:
> > On Wed, Feb 05, 2025 at 08:01:26PM +0000, Conor Dooley wrote:
> > > On Wed, Feb 05, 2025 at 08:33:13PM +0100, Lorenzo Bianconi wrote:
> > > > > On Wed, Feb 05, 2025 at 07:21:28PM +0100, Lorenzo Bianconi wrote:
> > > > > > Introduce the airoha,npu property for the npu syscon node available on
> > > > > > EN7581 SoC. The airoha Network Processor Unit (NPU) is used to offload
> > > > > > network traffic forwarded between Packet Switch Engine (PSE) ports.
> > > > > > 
> > > > > > Signed-off-by: Lorenzo Bianconi <lorenzo at kernel.org>
> > > > > > ---
> > > > > >  Documentation/devicetree/bindings/net/airoha,en7581-eth.yaml | 8 ++++++++
> > > > > >  1 file changed, 8 insertions(+)
> > > > > > 
> > > > > > diff --git a/Documentation/devicetree/bindings/net/airoha,en7581-eth.yaml b/Documentation/devicetree/bindings/net/airoha,en7581-eth.yaml
> > > > > > index c578637c5826db4bf470a4d01ac6f3133976ae1a..6388afff64e990a20230b0c4e58534aa61f984da 100644
> > > > > > --- a/Documentation/devicetree/bindings/net/airoha,en7581-eth.yaml
> > > > > > +++ b/Documentation/devicetree/bindings/net/airoha,en7581-eth.yaml
> > > > > > @@ -63,6 +63,12 @@ properties:
> > > > > >    "#size-cells":
> > > > > >      const: 0
> > > > > >  
> > > > > > +  airoha,npu:
> > > > > > +    $ref: /schemas/types.yaml#/definitions/phandle
> > > > > > +    description:
> > > > > > +      Phandle to the syscon node used to configure the NPU module
> > > > > > +      used for traffic offloading.
> > > > > 
> > > > > Why do you need a phandle for this, instead of a lookup by compatible?
> > > > > Do you have multiple instances of this ethernet controller on the
> > > > > device, that each need to look up a different npu?
> > > > 
> > > > actually not, but looking up via the compatible string has been naked by
> > > > Krzysztof on a different series [0].
> > > 
> > > Hmm, I disagree with adding phandles that are not needed. I don't agree
> > > that there's no reuse, if you can treat the phandle identically on a new
> > > device, in all likelihood, that node should have a fallback to the
> > > existing one.
> > 
> > Also, where is the binding for this npu? It looks like a brand-new
> > module that you're adding a driver for in this series and a phandle to
> > the node for here but I see no binding for it.
> 
> The driver loads the NPU node just as syscon so I have not added the binding
> for it to the series. I will add it in v2.

I don't think it is "just as syscon", you've got an entire driver for it
that you're loading via the phandle, it's not just some generic syscon that
you're looking up here - at least that's what it seemed like to me after
my scan of the driver patches.
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