On Mon, Feb 19, 2024 at 03:31:06PM +0100, Köry Maincent wrote: > On Fri, 16 Feb 2024 08:47:14 +0100 > Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx> wrote: > > > > > > So, either somebody needs to understand 1000BaseT and can say the > > > proposed binding works, or we explicitly document the binding is > > > limited to 10BaseT and 100BaseT. > > > > I asked the internet and found the answer: Some PSE/PD implementations > > are not compatible with 1000BaseT. > > > > See Figure 33–4—10BASE-T/100BASE-TX Endpoint PSE location overview. > > Alternative B show a variant where power is injected directly to pairs > > without using magnetics as it is done for Alternative A (phantom > > delivery - over magnetics). > > > > So, we have following variants of 2 pairs PoE: > > +---------+---------------+-------------------+---------------------+--------------------+ > > | Variant | Alternative | Polarity | Power Feeding Type | > > Compatibility with | | | (a/b) | (Direct/Reverse) | > > (Direct/Phantom) | 1000BaseT | > > +=========+===============+===================+=====================+====================+ > > | 1 | a | Direct | Phantom | Yes > > | > > +---------+---------------+-------------------+---------------------+--------------------+ > > | 2 | a | Reverse | Phantom | Yes > > | > > +---------+---------------+-------------------+---------------------+--------------------+ > > | 3 | b | Direct | Phantom | Yes > > | > > +---------+---------------+-------------------+---------------------+--------------------+ > > | 4 | b | Reverse | Phantom | Yes > > | > > +---------+---------------+-------------------+---------------------+--------------------+ > > | 5 | b | Direct | Direct | No > > | > > +---------+---------------+-------------------+---------------------+--------------------+ > > | 6 | b | Reverse | Direct | No > > | > > +---------+---------------+-------------------+---------------------+--------------------+ > > Maybe we could remove the polarity column on this table as it does not bring > more information. It is also already explained on the PI pinout alternatives > table. Ack. I'm still not sure if "Phantom" is correct description. > > Also we should document that a 4pairs PSE supporting only 10/100BaseT (which > mean no magnetics on pinout AlternativeB) may not be compatible with a 4pairs > 1GBaseT PD. Ack. s/may not/is not/ :) and 4pairs PSE is not always compatible with PoE4 as well. I assume this kind of knowledge we will get from PSE driver. Regards, Oleksij -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
