Re: [PATCH net-next v6 11/17] dt-bindings: net: pse-pd: Add another way of describing several PSE PIs

From: Rob Herring
Date: Wed Apr 03 2024 - 10:45:02 EST


On Tue, Apr 02, 2024 at 05:47:58PM +0200, Oleksij Rempel wrote:
> On Tue, Apr 02, 2024 at 08:26:37AM -0500, Rob Herring wrote:
> > > + pairsets:
> > > + $ref: /schemas/types.yaml#/definitions/phandle-array
> > > + description:
> > > + List of phandles, each pointing to the power supply for the
> > > + corresponding pairset named in 'pairset-names'. This property
> > > + aligns with IEEE 802.3-2022, Section 33.2.3 and 145.2.4.
> > > + PSE Pinout Alternatives (as per IEEE 802.3-2022 Table 145\u20133)
> > > + |-----------|---------------|---------------|---------------|---------------|
> > > + | Conductor | Alternative A | Alternative A | Alternative B | Alternative B |
> > > + | | (MDI-X) | (MDI) | (X) | (S) |
> > > + |-----------|---------------|---------------|---------------|---------------|
> > > + | 1 | Negative VPSE | Positive VPSE | \u2014 | \u2014 |
> > > + | 2 | Negative VPSE | Positive VPSE | \u2014 | \u2014 |
> > > + | 3 | Positive VPSE | Negative VPSE | \u2014 | \u2014 |
> > > + | 4 | \u2014 | \u2014 | Negative VPSE | Positive VPSE |
> > > + | 5 | \u2014 | \u2014 | Negative VPSE | Positive VPSE |
> > > + | 6 | Positive VPSE | Negative VPSE | \u2014 | \u2014 |
> > > + | 7 | \u2014 | \u2014 | Positive VPSE | Negative VPSE |
> > > + | 8 | \u2014 | \u2014 | Positive VPSE | Negative VPSE |
> > > + minItems: 1
> > > + maxItems: 2
> >
> > "pairsets" does not follow the normal design pattern of foos, foo-names,
> > and #foo-cells. You could add #foo-cells I suppose, but what would cells
> > convey? I don't think it's a good fit for what you need.
> >
> > The other oddity is the number of entries and the names are fixed. That
> > is usually defined per consumer.
> >
> > As each entry is just a power rail, why can't the regulator binding be
> > used here?
>
> I'm not against describing it consequent with regulator till the wire
> end, but right now I have no idea how it should be described by using
> regulator bindings. There are maximum 2 rails going in to PSE PI on one
> side and 4 rails with at least 5 combinations supported by standard on
> other side. Instead of inventing anything new, I suggested to describe
> supported output combinations by using IEEE 802.3 standard.

There's 4 combinations above, what's the 5th combination? SPE?

Seems to me you just describe the 2 rails going to the connector and
then describe all the variations the connector supports. The PSE
(h/w) has little to do with which variations are supported, right?
For example, MDI-X vs. MDI support is determined by the PHY, right? Or
it has to be supported by both the PHY and PSE?

Rob