linux-kernel - Re: [PATCH] net: phy: use generic clause 45 autonegotiation done

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Date:   Thu, 19 Jul 2018 13:56:35 +0100
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Camelia Alexandra Groza <camelia.groza@....com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: phy: use generic clause 45 autonegotiation done

On Thu, Jul 19, 2018 at 12:47:18PM +0000, Camelia Alexandra Groza wrote:
> > -----Original Message-----
> > From: Andrew Lunn [mailto:andrew@...n.ch]
> > Sent: Wednesday, July 18, 2018 17:39
> > To: Camelia Alexandra Groza <camelia.groza@....com>
> > Cc: f.fainelli@...il.com; davem@...emloft.net; netdev@...r.kernel.org;
> > linux-kernel@...r.kernel.org
> > Subject: Re: [PATCH] net: phy: use generic clause 45 autonegotiation done
> > 
> > On Wed, Jul 18, 2018 at 04:12:15PM +0300, Camelia Groza wrote:
> > > Only Clause 22 PHYs can use genphy_aneg_done(). Use
> > > genphy_c45_aneg_done() for PHYs that implement Clause 45 without the
> > > Clause 22 register set.
> > >
> > > This change follows the model of phy_restart_aneg() which
> > > differentiates between the two implementations in a similar way.
> > 
> > Hi Camelia
> > 
> > What about phy_config_aneg()? I would assume any sort of auto-neg action
> > needs to check for c45 without c22, before calling a genphy_ function. Do you
> > think it is possible to write a genphy_c45_config_aneg()? If not, we might
> > want to return -EOPNOTSUPP.
> 
> Hi Andrew,
> 
> Adding Russell to the thread as well, since he wrote the c45 helpers.
> 
> Sure, I'll send a v2 with an additional generic phy_config_aneg(). I'll
> stick to returning -EOPNOTSUPP for c22-less PHYs for now.

Be aware that there are no generic registers for configuring (eg) 1G
speeds in C45 phys - that is vendor specific.

It may be that the expectation in the 802.3 specs is that such PHYs
implement the C22 register set in devad 0, but I've no visibility of
that (and the 10G PHYs that phylib does have, apart from marvell10g,
are particularly poor in the features they implement.)

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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