RE: Re: [PATCH v4 1/4] dt-bindings: net: phy: Add support for NXP TJA11xx

RE: Re: [PATCH v4 1/4] dt-bindings: net: phy: Add support for NXP TJA11xx

[Christian Herber]

>On Sun, Mar 22, 2020 at 3:09 PM Florian Fainelli <f.fainelli@gmail.com> wrote:
>>
>> On 3/20/2020 4:05 PM, Rob Herring wrote:
>> >>>> Because the primary PHY0 can be autodetected by the bus scan.
>> >>>> But I have nothing against your suggestions. Please, some one should say the
>> >>>> last word here, how exactly it should be implemented?
>> >>
>> >> It's not for me to decide, I was hoping the Device Tree maintainers
>> >> could chime in, your current approach would certainly work although it
>> >> feels visually awkward.
>> >
>> > Something like this is what I'd do:
>> >
>> > ethernet-phy@4 {
>> >   compatible = "nxp,tja1102";
>> >   reg = <4 5>;
>> > };
>>
>> But the parent (MDIO bus controller) has #address-cells = 1 and
>> #size-cells = 0, so how can this be made to work without creating two
>> nodes or a first node encapsulating another one?
>
>That is the size of the address, not how many addresses there are. If
>the device has 2 addresses, then 2 address entries seems entirely
>appropriate.
>
>Rob

Yes, it is one device with two address. This is if you call the entire IC a device. If you look at it from a PHY perspective, it is two devices with 1 address.
If you just look at it as a single device, it gets difficult to add PHY specific properties in the future, e.g. master/slave selection.
In my opinion its important to have some kind of container for the entire IC, but likewise for the individual PHYs.

Christian

Re: Re: [PATCH v4 1/4] dt-bindings: net: phy: Add support for NXP TJA11xx

[Andrew Lunn]

> Yes, it is one device with two address. This is if you call the entire IC a device. If you look at it from a PHY perspective, it is two devices with 1 address.
> If you just look at it as a single device, it gets difficult to add PHY specific properties in the future, e.g. master/slave selection.

> In my opinion its important to have some kind of container for the
> entire IC, but likewise for the individual PHYs.

Yes, we need some sort of representation of two devices.

Logically, the two PHYs are on the same MDIO bus, so you could have
two nodes on the main bus.

Or you consider the secondary PHY as being on an internal MDIO bus
which is transparently bridged to the main bus. This is what was
proposed in the last patchset.

Because this bridge is transparent, the rest of the PHY/MDIO framework
has no idea about it. So i prefer that we keep with two PHY nodes on
the main bus. But i still think we need the master PHY to register the
secondary PHY, due to the missing PHY ID, and the other constrains
like resets which the master PHY has to handle.

     Andrew

Re: Re: [PATCH v4 1/4] dt-bindings: net: phy: Add support for NXP TJA11xx

[Oleksij Rempel]

Hi,

On Mon, Mar 23, 2020 at 04:14:23PM +0100, Andrew Lunn wrote:
> > Yes, it is one device with two address. This is if you call the entire IC a device. If you look at it from a PHY perspective, it is two devices with 1 address.
> > If you just look at it as a single device, it gets difficult to add PHY specific properties in the future, e.g. master/slave selection.
> 
> > In my opinion its important to have some kind of container for the
> > entire IC, but likewise for the individual PHYs.
> 
> Yes, we need some sort of representation of two devices.
> 
> Logically, the two PHYs are on the same MDIO bus, so you could have
> two nodes on the main bus.
> 
> Or you consider the secondary PHY as being on an internal MDIO bus
> which is transparently bridged to the main bus. This is what was
> proposed in the last patchset.
> 
> Because this bridge is transparent, the rest of the PHY/MDIO framework
> has no idea about it. So i prefer that we keep with two PHY nodes on
> the main bus. But i still think we need the master PHY to register the
> secondary PHY, due to the missing PHY ID, and the other constrains
> like resets which the master PHY has to handle.

this discussion is stalled.
What is the final decision? What is the proper and mainlinable way?

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 |

Re: Re: [PATCH v4 1/4] dt-bindings: net: phy: Add support for NXP TJA11xx

[Oleksij Rempel]

On Mon, Mar 23, 2020 at 04:14:23PM +0100, Andrew Lunn wrote:
> > Yes, it is one device with two address. This is if you call the entire IC a device. If you look at it from a PHY perspective, it is two devices with 1 address.
> > If you just look at it as a single device, it gets difficult to add PHY specific properties in the future, e.g. master/slave selection.
> 
> > In my opinion its important to have some kind of container for the
> > entire IC, but likewise for the individual PHYs.
> 
> Yes, we need some sort of representation of two devices.
> 
> Logically, the two PHYs are on the same MDIO bus, so you could have
> two nodes on the main bus.
> 
> Or you consider the secondary PHY as being on an internal MDIO bus
> which is transparently bridged to the main bus. This is what was
> proposed in the last patchset.
> 
> Because this bridge is transparent, the rest of the PHY/MDIO framework
> has no idea about it. So i prefer that we keep with two PHY nodes on
> the main bus. But i still think we need the master PHY to register the
> secondary PHY, due to the missing PHY ID, and the other constrains
> like resets which the master PHY has to handle.

Yes, this is the way how current patches are implemented.

Should dt-binding documentation and PHY changes go via David's tree
upstream?  If nobody has strong opinion against it, @David can you
please take them.

Regards,
Oleksij & Marc
-- 
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 |