linux-kernel - Re: [PATCH net-next 5/7] net: phy: marvell10g: Force reading of 2.5/5G PMA extended abilities

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Message-ID: <20190121105206.mxxxosytk5qiysc2@e5254000004ec.dyn.armlinux.org.uk>
Date:   Mon, 21 Jan 2019 10:52:06 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Maxime Chevallier <maxime.chevallier@...tlin.com>
Cc:     Andrew Lunn <andrew@...n.ch>, davem@...emloft.net,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Florian Fainelli <f.fainelli@...il.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        linux-arm-kernel@...ts.infradead.org,
        Antoine Tenart <antoine.tenart@...tlin.com>,
        thomas.petazzoni@...tlin.com, gregory.clement@...tlin.com,
        miquel.raynal@...tlin.com, nadavh@...vell.com, stefanc@...vell.com,
        mw@...ihalf.com
Subject: Re: [PATCH net-next 5/7] net: phy: marvell10g: Force reading of
 2.5/5G PMA extended abilities

On Mon, Jan 21, 2019 at 11:35:31AM +0100, Maxime Chevallier wrote:
> Hello Andrew,
> 
> On Sun, 20 Jan 2019 20:08:09 +0100
> Andrew Lunn <andrew@...n.ch> wrote:
> 
> >On Fri, Jan 18, 2019 at 04:23:50PM +0100, Maxime Chevallier wrote:
> >> As per 802.3bz, if bit 14 of (1.11) "PMA Extended Abilities" indicates
> >> whether or not we should read register (1.21) "2.52/5G PMA Extended
> >> Abilities", which contains information on the support of 2.5GBASET and
> >> 5GBASET.
> >> 
> >> After testing on several variants of PHYS of this family, it appears
> >> that bit 14 in (1.11) isn't always set when it should be.
> >> 
> >> PHYs 88X3310 (on MacchiatoBin) and 88E2010 do support 2.5G and 5GBASET,
> >> but don't have 1.11.14 set. Their register 1.21 is filled with the
> >> correct values, indicating 2.5G and 5G support.
> >> 
> >> PHYs 88X2110 do have their 1.11.14 bit set, as it should.  
> >
> >Hi Maxime
> >
> >Is there anything about this in any Errata?
> 
> I haven't seen any Errata on that unfortunately.
> 
> I also thought about reading (1.4) "PMA/PMD Speed Ability", but the
> 2.5G and 5G speeds are also reported as not being supported on the
> 88X3310.

It's entirely possible that the 3310 switches to different hardware
blocks for 2.5G and 5G speeds, and reading _just_ the 1.4 register
is not sufficient.

The 88x3310 is multiple PHY devices in one package, with a CPU that
manages the routing between each individual device.

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