On Mon, 22 Mar 2021 19:56:05 +0000 Russell King - ARM Linux admin <linux@xxxxxxxxxxxxxxx> wrote: > On Mon, Mar 22, 2021 at 08:49:59PM +0100, Marek Behún wrote: > > diff --git a/Documentation/devicetree/bindings/net/ethernet-phy.yaml b/Documentation/devicetree/bindings/net/ethernet-phy.yaml > > index 2766fe45bb98..4c5b8fabbec3 100644 > > --- a/Documentation/devicetree/bindings/net/ethernet-phy.yaml > > +++ b/Documentation/devicetree/bindings/net/ethernet-phy.yaml > > @@ -136,6 +136,20 @@ properties: > > used. The absence of this property indicates the muxers > > should be configured so that the external PHY is used. > > > > + unsupported-mac-connection-types: > > + $ref: "ethernet-controller.yaml#/$defs/phy-connection-type-array" > > + description: > > + The PHY device may support different interface types for > > + connecting the Ethernet MAC device to the PHY device (i.e. > > + rgmii, sgmii, xaui, ...), but not all of these interface > > + types must necessarily be supported for a specific board > > + (either not all of them are wired, or there is a known bug > > + for a specific mode). > > + This property specifies a list of interface modes are not > > + supported on the board. > > I think this needs to be clearer. "This property specifies a list > of interface modes supported by the PHY hardware but are not > supported on the board." > > I would also suggest having a think about a PHY that supports some > interface types that we don't have support in the kernel for, but > which also are not part of the board. Should these be listed > somehow as well? If not, how do we deal with the kernel later gaining > support for those interface modes, potentially the PHY driver as well, > and then having a load of boards not listing this? > > My feeling is that listing negative properties presents something of > a problem, and we ought to stick with boards specifying what they > support, rather than what they don't. That is a good point. And if this alternative `supported-modes` property is missing, we can just assume that all modes are supported, in order to be backward compatible.
