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From:   Vladimir Oltean <olteanv@gmail.com>
Date:   Tue, 10 Dec 2019 19:05:08 +0200
Message-ID: <CA+h21hp12UGQ04W4rDo2PdFa2_5oMmX05KKUecdz5-+hv-JqAA@mail.gmail.com>
Subject: Re: [PATCH net-next 4/6] net: dsa: mt7530: Add the support of MT7531 switch
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     Landen Chao <landen.chao@mediatek.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vivien Didelot <vivien.didelot@savoirfairelinux.com>,
        matthias.bgg@gmail.com, Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        devicetree@vger.kernel.org, netdev <netdev@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        linux-mediatek@lists.infradead.org,
        "David S. Miller" <davem@davemloft.net>, sean.wang@mediatek.com,
        =?UTF-8?Q?Ren=C3=A9_van_Dorst?= <opensource@vdorst.com>,
        frank-w@public-files.de
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Hi Landen, Andrew,

On Tue, 10 Dec 2019 at 18:36, Andrew Lunn <andrew@lunn.ch> wrote:
>
> On Tue, Dec 10, 2019 at 04:14:40PM +0800, Landen Chao wrote:
> > Add new support for MT7531:
> >
> > MT7531 is the next generation of MT7530. It is also a 7-ports switch with
> > 5 giga embedded phys, 2 cpu ports, and the same MAC logic of MT7530. Cpu
> > port 6 only supports HSGMII interface. Cpu port 5 supports either RGMII
> > or HSGMII in different HW sku.
>
> Hi Landen
>
> Looking at the code, you seem to treat HSGMII as 2500Base-X. Is this
> correct? Or is it SGMII over clocked to 2.5Gbps?
>
>          Andrew

I think the better question is: what is being understood by HSGMII?
What does the AN base page look like? Do you support AN with the 2500
baud speed? Do you support AN with lower speeds? Do you support lower
speeds at all? What PHYs do you interoperate with in this mode? If you
don't support AN, then what's so SGMII about it? And for that matter,
if you don't support AN, what's so 2500Base-X (802.3z) about it? I see
you unconditionally force the speed and disable AN in this mode. Do
you have any reference for what SerDes protocol your hardware
implements in this mode?

Thanks,
-Vladimir