netdev - Re: [PATCH 5/5] net: phy: dp83867: Use unsigned variables to store unsigned properties

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Message-ID: <1557848224.4229.48.camel@impinj.com>
Date:   Tue, 14 May 2019 15:37:05 +0000
From:   Trent Piepho <tpiepho@...inj.com>
To:     "andrew@...n.ch" <andrew@...n.ch>
CC:     "hkallweit1@...il.com" <hkallweit1@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH 5/5] net: phy: dp83867: Use unsigned variables to store
 unsigned properties

On Mon, 2019-05-13 at 23:43 +0200, Andrew Lunn wrote:
> > > 
> > > Are there any in tree users of DP83867_CLK_O_SEL_REF_CLK? We have to
> > > be careful changing its meaning. But if nobody is actually using it...
> > 
> > Nope.  I doubt this will affect anyone.  They'd need to strap the phy
> > to get a different configuration, and the explicitly add a property,
> > which isn't in the example DTS files, to change the configuration to
> > something they didn't want, and then depend on a driver bug ignoring
> > the erroneous setting they added.
> 
> O.K, then this patch is O.K. Does the binding documentation need
> updating?

Device tree binding patch was split out of the commit and was patch 2
of the series, https://patchwork.ozlabs.org/patch/1098349/

> > > Patch 4:
> > > 
> > > This is harder. Ideally we want to fix this. At some point, somebody
> > > is going to want 'rgmii' to actually mean 'rgmii', because that is
> > > what their hardware needs.
> > > 
> > > Could you add a WARN_ON() for 'rgmii' but the PHY is actually adding a
> > > delay? And add a comment about setting the correct thing in device
> > > tree?  Hopefully we will then get patches correcting DT blobs. And if
> > > we later do need to fix 'rgmii', we will break less board.
> > 
> > Yes I can do this.  Should it warn on any use of "rgmii"?
> 
> No, i would only warn when there is a delay configured by
> strapping. If you want the PHY to be left alone, you should use
> PHY_INTERFACE_MODE_NA, which should be the default if there is no
> phy-mode property. If DT actually asked for "rgmii", it either means
> it is wrong and rgmii-id should be used to match the strapping, or
> both the strapping and the DT is wrong and somebody really does want
> "rgmii".

Ok, seems reasonable.  I've put in a phydev_warn() when the interface
is 'rgmii' and the strapping is set to have a delay.  I'm checking the
strapping config register for this, rather than the current phy
configuration of delay values.  The previous behavior of 'rgmii' mode
was "keep strapping default", rather than "keep current phy
configuration", which isn't exactly the same thing.

Here is the message:

phydev_warn(phydev,
            "PHY has delays via pin strapping, but phy-mode = 'rgmii'\n"
            "Should be 'rgmii-id' to use internal delays\n");