RE: [PATCH v2 net-next 2/3] net: phy: tja11xx: replace "nxp,rmii-refclk-in" with "nxp,phy-output-refclk"

[Wei Fang]

> -----Original Message-----
> From: Conor Dooley <conor@xxxxxxxxxx>
> Sent: 2024年8月23日 0:14
> To: Wei Fang <wei.fang@xxxxxxx>
> Cc: davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx;
> pabeni@xxxxxxxxxx; robh@xxxxxxxxxx; krzk+dt@xxxxxxxxxx;
> conor+dt@xxxxxxxxxx; andrew@xxxxxxx; f.fainelli@xxxxxxxxx;
> hkallweit1@xxxxxxxxx; linux@xxxxxxxxxxxxxxx; Andrei Botila (OSS)
> <andrei.botila@xxxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v2 net-next 2/3] net: phy: tja11xx: replace
> "nxp,rmii-refclk-in" with "nxp,phy-output-refclk"
> 
> On Thu, Aug 22, 2024 at 09:37:11AM +0000, Wei Fang wrote:
> > > -----Original Message-----
> > > From: Conor Dooley <conor@xxxxxxxxxx>
> > > Sent: 2024年8月22日 16:47
> > > To: Wei Fang <wei.fang@xxxxxxx>
> > > Cc: davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx;
> > > pabeni@xxxxxxxxxx; robh@xxxxxxxxxx; krzk+dt@xxxxxxxxxx;
> > > conor+dt@xxxxxxxxxx; andrew@xxxxxxx; f.fainelli@xxxxxxxxx;
> > > hkallweit1@xxxxxxxxx; linux@xxxxxxxxxxxxxxx; Andrei Botila (OSS)
> > > <andrei.botila@xxxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx;
> > > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> > > Subject: Re: [PATCH v2 net-next 2/3] net: phy: tja11xx: replace
> > > "nxp,rmii-refclk-in" with "nxp,phy-output-refclk"
> > >
> > > On Thu, Aug 22, 2024 at 09:37:20AM +0800, Wei Fang wrote:
> > > > As the new property "nxp,phy-output-refclk" is added to instead of
> > > > the "nxp,rmii-refclk-in" property, so replace the "nxp,rmii-refclk-in"
> > > > property used in the driver with the "nxp,reverse-mode" property
> > > > and make slight modifications.
> > >
> > > Can you explain what makes this backwards compatible please?
> > >
> > It does not backward compatible, the related PHY nodes in DTS also
> > need to be updated. I have not seen "nxp,rmii-refclk-in" used in the
> > upstream.
> 
> Since you have switched the polarity, devicestrees that contain
> "nxp,rmii-refclk-in" would actually not need an update to preserve
> functionality. However...
> 
> > For nodes that do not use " nxp,rmii-refclk-in", they need to be
> > updated, but unfortunately I cannot confirm which DTS use TJA11XX PHY,
> > and there may be no relevant nodes in upstream DTS.
> 
> ...as you say here, all tja11xx phy nodes that do not have the property would
> need to be updated to retain functionality. Given you can't even determine
> which devicetrees would need to be updated, I'm going to have to NAK this
> change as an unnecessary ABI break.
> 

Okay, that make sense, "nxp,rmii-refclk-in" was added only for TJA1100 and
TJA1101, although it does not seem to be a suitable property now, it cannot
be changed at present. :(
Since TJA1103/TJA1104/TJA1120/TJA1121 use different driver than TJA1100
and TJA1101, which is nxp-c4-tja11xx. I think it's fine to add " nxp,phy-output-refclk "
for these PHYs, so I will remove this patch from the patch set.