netdev - RE: [PATCH v1] net: phy: adin: Add flags to disable enhanced link detection

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Message-ID: <DU0PR08MB9003DF34A62F764A90F70FE5ECAC9@DU0PR08MB9003.eurprd08.prod.outlook.com>
Date:   Tue, 28 Feb 2023 15:28:43 +0000
From:   Ken Sloat <ken.s@...iscite.com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     Michael Hennerich <michael.hennerich@...log.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Ken Sloat <ken.s@...iscite.com>
Subject: RE: [PATCH v1] net: phy: adin: Add flags to disable enhanced link
 detection

Thanks Andrew!

> -----Original Message-----
> From: Andrew Lunn <andrew@...n.ch>
> Sent: Tuesday, February 28, 2023 10:19 AM
> To: Ken Sloat <ken.s@...iscite.com>
> Cc: Michael Hennerich <michael.hennerich@...log.com>; Heiner Kallweit
> <hkallweit1@...il.com>; Russell King <linux@...linux.org.uk>; David S.
> Miller <davem@...emloft.net>; Jakub Kicinski <kuba@...nel.org>;
> netdev@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH v1] net: phy: adin: Add flags to disable enhanced link
> detection
> 
> On Tue, Feb 28, 2023 at 03:13:59PM +0000, Ken Sloat wrote:
> > Hi Andrew,
> >
> > Thanks for your quick reply!
> >
> > > -----Original Message-----
> > > From: Andrew Lunn <andrew@...n.ch>
> > > Sent: Tuesday, February 28, 2023 9:53 AM
> > > To: Ken Sloat <ken.s@...iscite.com>
> > > Cc: Michael Hennerich <michael.hennerich@...log.com>; Heiner
> > > Kallweit <hkallweit1@...il.com>; Russell King <linux@...linux.org.uk>;
> David S.
> > > Miller <davem@...emloft.net>; Jakub Kicinski <kuba@...nel.org>;
> > > netdev@...r.kernel.org; linux-kernel@...r.kernel.org
> > > Subject: Re: [PATCH v1] net: phy: adin: Add flags to disable
> > > enhanced link detection
> > >
> > > On Tue, Feb 28, 2023 at 09:40:56AM -0500, Ken Sloat wrote:
> > > > Enhanced link detection is an ADI PHY feature that allows for
> > > > earlier detection of link down if certain signal conditions are
> > > > met. This feature is for the most part enabled by default on the
> > > > PHY. This is not suitable for all applications and breaks the IEEE
> > > > standard as explained in the ADI datasheet.
> > > >
> > > > To fix this, add override flags to disable enhanced link detection
> > > > for 1000BASE-T and 100BASE-TX respectively by clearing any related
> > > > feature enable bits.
> > > >
> > > > This new feature was tested on an ADIN1300 but according to the
> > > > datasheet applies equally for 100BASE-TX on the ADIN1200.
> > > >
> > > > Signed-off-by: Ken Sloat <ken.s@...iscite.com>
> > > Hi Ken
> > >
> > > > +static int adin_config_fld_en(struct phy_device *phydev)
> > >
> > > Could we have a better name please. I guess it means Fast Link Down,
> > > but the commit messages talks about Enhanced link detection. This
> > > function is also not enabling fast link down, but disabling it, so _en seems
> wrong.
> > >
> > "Enhanced Link Detection" is the ADI term, but the associated register for
> controlling this feature is called "FLD_EN." I considered "ELD" as that makes
> more sense language wise but it did not match the datasheet and did not
> want to invent a new term. I was not sure what the F was but perhaps you
> are right, as the link is brought down as part of this feature when conditions
> are met. I am guessing then that this FLD is a carryover from some initial
> name of the feature that was later re-branded.
> >
> > I am happy to change fld -> eld or something else that might make more
> sense for users and am open to any suggestions.
> 
> The Marvell PHYs also support a fast link down mode, so i think using fast link
> down everywhere, in the code and the commit message would be good.
> How about adin_fast_down_disable().
> 
I am good with that. I'll probably also make mention in the comment along with that ADI's term for thoroughness.

What about for the bindings, how is something like "adi,disable-fast-down-1000base-t?"

> > > You need to document these two properties in the device tree binding.
> > >
> >
> > I already have a separate patch for this. I will send both patches
> > when I re-submit and CC additional parties.
> 
> It is normal to submit them together as a patch set. What generally happens
> is that the DT maintainers ACK the documentation patch, and then it gets
> merged via the netdev tree.
> 
Good to know thanks!

>    Andrew

Sincerely,
Ken Sloat