Re: [PATCH RFT 1/2] phylib: add device reset GPIO support

[Sergei Shtylyov]

Hello.

On 05/14/2016 10:50 PM, Andrew Lunn wrote:

> > > > > > > Another issue is that on some boards we have one reset line tied to
> > > > > > > multiple PHYs.How do we prevent multiple resets being taking place when each of
> > > > > > > the PHYs are registered?
> > > > > >
> > > > > >  My patch just doesn't address this case -- it's about the
> > > > > > individual resets only.
> > > > >
> > > > > This actually needs to be addresses a layer above. What you have is a
> > > > > bus reset, not a device reset.
> > > >
> > > >   No.
> > > >   There's simply no such thing as a bus reset for the xMII/MDIO
> > > > busses, there's simply no reset signaling on them. Every device has
> > > > its own reset signal and its own timing requirements.
> > >
> > > Except in the case above, where two phys are sharing the same reset
> > > signal. So although it is not part of the mdio standard to have a bus
> > > reset, this is in effect what the gpio line is doing, resetting all
> > > devices on the bus. If you don't model that as a bus reset, how do you
> > > model it?
> >
> >    I'm not suggesting that the shared reset should be handled by my
> > patch. Contrariwise, I suggested to use the mii_bus::reset() method
>
> I think we miss understood each other somewhere.
>
> Your code is great for one gpio reset line for one phy.
>
> I think there could be similar code one layer above to handle one gpio
> line for multiple phys.

   Ah, you want me to recognize some MAC/MDIO bound prop (e.g. 
"mdio-reset-gpios") in of_mdiobus_register()? I'll think about it now that my 
patch needs fixing anyway...

>      Andrew

MBR, Sergei