netdev - Re: [PATCH net-next v3 2/3] net: ethernet: mediatek: Re-add support SGMII

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Message-ID: <20190824131117.Horde.vSCF_CQ5jCMHcSTWkh7Woxm@www.vdorst.com>
Date:   Sat, 24 Aug 2019 13:11:17 +0000
From:   René van Dorst <opensource@...rst.com>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>
Cc:     John Crispin <john@...ozen.org>,
        Sean Wang <sean.wang@...iatek.com>,
        Nelson Chang <nelson.chang@...iatek.com>,
        "David S . Miller" <davem@...emloft.net>,
        Matthias Brugger <matthias.bgg@...il.com>,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-mips@...r.kernel.org,
        Frank Wunderlich <frank-w@...lic-files.de>,
        Stefan Roese <sr@...x.de>
Subject: Re: [PATCH net-next v3 2/3] net: ethernet: mediatek: Re-add support
 SGMII

Hi Russell,

Quoting Russell King - ARM Linux admin <linux@...linux.org.uk>:

> On Fri, Aug 23, 2019 at 03:45:15PM +0200, René van Dorst wrote:
>> +	switch (state->interface) {
>> +	case PHY_INTERFACE_MODE_SGMII:
>> +		phylink_set(mask, 10baseT_Half);
>> +		phylink_set(mask, 10baseT_Full);
>> +		phylink_set(mask, 100baseT_Half);
>> +		phylink_set(mask, 100baseT_Full);
>
> You also want 1000baseX_Full here - the connected PHY could have a fiber
> interface on it.

Ok, I shall add that mode too.

>
>> +		/* fall through */
>> +	case PHY_INTERFACE_MODE_TRGMII:
>>  		phylink_set(mask, 1000baseT_Full);
>
> I don't know enough about this interface type to comment whether it
> should support 1000baseX_Full - if this is connected to a PHY that may
> support fiber, then it ought to set it.

Mediatek calls it Turbo RGMII. It is a overclock version of RGMII mode.
It is used between first GMAC and port 6 of the mt7530 switch. Can be  
used with
an internal and an external mt7530 switch.

TRGMII speed are:
* mt7621: 1200Mbit
* mt7623: 2000Mbit and 2600Mbit.

I think that TRGMII is only used in a fixed-link situation in  
combination with a
mt7530 switch and running and maximum speed/full duplex. So reporting
1000baseT_Full seems to me the right option.

>
>> +		break;
>> +	case PHY_INTERFACE_MODE_2500BASEX:
>> +		phylink_set(mask, 2500baseX_Full);
>> +		/* fall through */
>> +	case PHY_INTERFACE_MODE_1000BASEX:
>> +		phylink_set(mask, 1000baseX_Full);
>
> Both should be set.  The reasoning here is that if you have a
> Fiberchannel 4Gbaud SFP plugged in and connected directly to the
> MAC, it can operate at either 2500Base-X or 1000Base-X.  If we
> decide to operate at 2500Base-X, then PHY_INTERFACE_MODE_2500BASEX
> will be chosen.  Otherwise, PHY_INTERFACE_MODE_1000BASEX will be
> used.
>
> The user can use ethtool to control which interface mode is used
> by adjusting the advertise mask and/or placing the interface in
> manual mode and setting the speed directly.  This will change
> the PHY_INTERFACE_MODE_xxxxBASEX (via phylink_helper_basex_speed())
> between the two settings.
>
> If we lose 2500baseX_Full when 1000Base-X is selected, the user
> will not be able to go back to 2500Base-X mode.
>
> Yes, it's a little confusing and has slightly different rules
> from the other modes - partly due to phylink_helper_basex_speed().
> These are the only interface modes that we dynamically switch
> between depending on the settings that the user configures via
> ethtool.

Thanks for this extra information.


I made a list for each mode what that mode should report back when chosen.

PHY_INTERFACE_MODE_SGMII:
	  10baseT_Half
	  10baseT_Full
	 100baseT_Half
	 100baseT_Full
	1000baseT_Full
	1000baseX_Full

PHY_INTERFACE_MODE_1000BASEX:
PHY_INTERFACE_MODE_2500BASEX:
	1000baseX_Full
	2500baseX_Full

PHY_INTERFACE_MODE_TRGMII:
	1000baseT_Full

PHY_INTERFACE_MODE_RGMII:
PHY_INTERFACE_MODE_RGMII_ID:
PHY_INTERFACE_MODE_RGMII_RXID:
PHY_INTERFACE_MODE_RGMII_TXID:
	  10baseT_Half
	  10baseT_Full
	 100baseT_Half
	 100baseT_Full
	1000baseT_Half
	1000baseT_Full
	1000baseX_Full

PHY_INTERFACE_MODE_GMII:
	  10baseT_Half
	  10baseT_Full
	 100baseT_Half
	 100baseT_Full
	1000baseT_Half
	1000baseT_Full

PHY_INTERFACE_MODE_MII:
PHY_INTERFACE_MODE_RMII:
PHY_INTERFACE_MODE_REVMII:
	 10baseT_Half
	 10baseT_Full
	100baseT_Half
	100baseT_Full

case PHY_INTERFACE_MODE_NA:
	  10baseT_Half
	  10baseT_Full
	 100baseT_Half
	 100baseT_Full
	1000baseT_Half
	1000baseT_Full
	1000baseX_Full
	2500baseX_Full

I think this is the full list.
Or do I miss something?

Greats,

René

>
> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
> According to speedtest.net: 11.9Mbps down 500kbps up