On Sat, 17 Feb 2024 13:14:29 +0100
Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx> wrote:
> On Thu, Feb 15, 2024 at 05:02:55PM +0100, Kory Maincent wrote:
> > Add the PD692x0 I2C Power Sourcing Equipment controller device tree
> > bindings documentation.
> >
> > This patch is sponsored by Dent Project <dentproject@xxxxxxxxxxxxxxxxxxx>.
> >
> > Signed-off-by: Kory Maincent <kory.maincent@xxxxxxxxxxx>
> > ---
> ...
> > + pse_pis {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > +
> > + pse_pi0: pse_pi@0 {
> > + reg = <0>;
> > + #pse-cells = <0>;
> > + pairset-names = "alternative-a", "alternative-b";
> > + pairsets = <&phys0>, <&phys1>;
> > + };
> > + pse_pi1: pse_pi@1 {
> > + reg = <1>;
> > + #pse-cells = <0>;
> > + pairset-names = "alternative-a";
> > + pairsets = <&phys2>;
>
> According to latest discussions, PSE PI nodes will need some
> additional, board specific, information:
> - this controller do not implements polarity switching, we need to know
> what polarity is implemented on this board. The 802.3 spec provide not
> really consistent names for polarity configurations:
> - Alternative A MDI-X
> - Alternative A MDI
> - Alternative B X
> - Alternative B S
> The board may implement one of polarity configurations per alternative
> or have additional helpers to switch them without using PSE
> controller.
> Even if specification explicitly say:
> "The PD shall be implemented to be insensitive to the polarity of the power
> supply and shall be able to operate per the PD Mode A column and the PD
> Mode B column in Table 33–13"
> it is possible to find reports like this:
> https://community.ui.com/questions/M5-cant-take-reversed-power-polarity-/d834d9a8-579d-4f08-80b1-623806cc5070
Mmh not sure we want to support broken cases that does not follow the spec.
Should we?
Regards,
--
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com
