Re: [PATCH net-next v3 2/4] dt-bindings: net: Add Rx/Tx output configuration for 10base T1L
From: Rob Herring
Date: Wed Nov 04 2020 - 17:08:34 EST
On Fri, Oct 30, 2020 at 08:56:55PM +0100, Andrew Lunn wrote:
> On Fri, Oct 30, 2020 at 12:29:48PM -0500, Dan Murphy wrote:
> > Per the 802.3cg spec the 10base T1L can operate at 2 different
> > differential voltages 1v p2p and 2.4v p2p. The abiility of the PHY to
> > drive that output is dependent on the PHY's on board power supply.
>
> Hi Dan
>
> So this property is about the board being able to support the needed
> voltages? The PHY is not forced into 2.4v p2p, it just says the PHY
> can operate at 2.4v and the board will not melt, blow a fuse, etc?
>
> I actually think it is normal to specify the reverse. List the maximum
> that device can do because of board restrictions. e.g.
>
> - maximum-power-milliwatt : Maximum module power consumption
> Specifies the maximum power consumption allowable by a module in the
> slot, in milli-Watts. Presently, modules can be up to 1W, 1.5W or 2W.
>
> - max-link-speed:
> If present this property specifies PCI gen for link capability. Host
> drivers could add this as a strategy to avoid unnecessary operation for
> unsupported link speed, for instance, trying to do training for
> unsupported link speed, etc. Must be '4' for gen4, '3' for gen3, '2'
> for gen2, and '1' for gen1. Any other values are invalid.
>
> - max-microvolt : The maximum voltage value supplied to the haptic motor.
> [The unit of the voltage is a micro]
>
> So i think this property should be
>
> max-tx-rx-p2p = <1000>;
>
> to limit it to 1000mv p2p because of board PSU limitations, and it is
> free to do 22000mv is the property is not present.
'-microvolt' suffix please.
>
> Andrew
>