From: Andrew Lunn <andrew@lunn.ch>
To: Steve Douthit <stephend@silicom-usa.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
"David S. Miller" <davem@davemloft.net>,
"intel-wired-lan@lists.osuosl.org"
<intel-wired-lan@lists.osuosl.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Florian Fainelli <f.fainelli@gmail.com>
Subject: Re: [PATCH net-next v2 1/2] ixgbe: register a mdiobus
Date: Mon, 3 Dec 2018 19:54:45 +0100 [thread overview]
Message-ID: <20181203185445.GO25748@lunn.ch> (raw)
In-Reply-To: <8ff5f4f0-9a4a-d601-3add-fcfc91b6414d@silicom-usa.com>
> You can actually strap the 6390 and friends for a multi-chip mode where
> they claim only a single address, instead of one per port, plus a couple
> more for global registers. It vastly slows things down because of the
> extra indirection, but it allows the switch to play nicely with other
> MDIO devs.
As you say, it slows things down a lot, so it is not used very often.
In fact, i don't know of any recent board which actually uses a single
address, for any DSA supported switch.
If you need multiple devices, e.g. an odd PHY as well as a switch, i
would use a couple of GPIO lines and do a bit-banging MDIO bus for the
PHY, and let the switch have all the address of the hardware MDIO bus.
This assumes you are using the kernel infrastructure, so you can
connect the MAC to any arbitrary PHY.
Andrew
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Lunn <andrew@lunn.ch>
To: intel-wired-lan@osuosl.org
Subject: [Intel-wired-lan] [PATCH net-next v2 1/2] ixgbe: register a mdiobus
Date: Mon, 3 Dec 2018 19:54:45 +0100 [thread overview]
Message-ID: <20181203185445.GO25748@lunn.ch> (raw)
In-Reply-To: <8ff5f4f0-9a4a-d601-3add-fcfc91b6414d@silicom-usa.com>
> You can actually strap the 6390 and friends for a multi-chip mode where
> they claim only a single address, instead of one per port, plus a couple
> more for global registers. It vastly slows things down because of the
> extra indirection, but it allows the switch to play nicely with other
> MDIO devs.
As you say, it slows things down a lot, so it is not used very often.
In fact, i don't know of any recent board which actually uses a single
address, for any DSA supported switch.
If you need multiple devices, e.g. an odd PHY as well as a switch, i
would use a couple of GPIO lines and do a bit-banging MDIO bus for the
PHY, and let the switch have all the address of the hardware MDIO bus.
This assumes you are using the kernel infrastructure, so you can
connect the MAC to any arbitrary PHY.
Andrew
next prev parent reply other threads:[~2018-12-03 18:54 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-03 16:32 [PATCH net-next v2 0/2] Add mii_bus to ixgbe driver for dsa devs Steve Douthit
2018-12-03 16:32 ` [Intel-wired-lan] " Steve Douthit
2018-12-03 16:32 ` [PATCH net-next v2 1/2] ixgbe: register a mdiobus Steve Douthit
2018-12-03 16:32 ` [Intel-wired-lan] " Steve Douthit
2018-12-03 16:54 ` Andrew Lunn
2018-12-03 16:54 ` [Intel-wired-lan] " Andrew Lunn
2018-12-03 17:02 ` Steve Douthit
2018-12-03 17:02 ` [Intel-wired-lan] " Steve Douthit
2018-12-03 17:21 ` Andrew Lunn
2018-12-03 17:21 ` [Intel-wired-lan] " Andrew Lunn
2018-12-03 17:59 ` Steve Douthit
2018-12-03 17:59 ` [Intel-wired-lan] " Steve Douthit
2018-12-03 18:18 ` Andrew Lunn
2018-12-03 18:18 ` [Intel-wired-lan] " Andrew Lunn
2018-12-03 18:38 ` Steve Douthit
2018-12-03 18:38 ` [Intel-wired-lan] " Steve Douthit
2018-12-03 18:54 ` Andrew Lunn [this message]
2018-12-03 18:54 ` Andrew Lunn
2018-12-03 16:33 ` [PATCH net-next v2 2/2] ixgbe: use mii_bus to handle MII related ioctls Steve Douthit
2018-12-03 16:33 ` [Intel-wired-lan] " Steve Douthit
2018-12-03 18:55 ` [PATCH net-next v3 0/2] Add mii_bus to ixgbe driver for dsa devs Steve Douthit
2018-12-03 18:55 ` [Intel-wired-lan] " Steve Douthit
2018-12-03 18:55 ` [PATCH net-next v3 1/2] ixgbe: register a mdiobus Steve Douthit
2018-12-03 18:55 ` [Intel-wired-lan] " Steve Douthit
2018-12-03 19:00 ` Andrew Lunn
2018-12-03 19:00 ` [Intel-wired-lan] " Andrew Lunn
2018-12-03 19:07 ` Florian Fainelli
2018-12-03 19:07 ` [Intel-wired-lan] " Florian Fainelli
2018-12-03 19:44 ` Steve Douthit
2018-12-03 19:44 ` [Intel-wired-lan] " Steve Douthit
2018-12-03 19:45 ` Florian Fainelli
2018-12-03 19:45 ` [Intel-wired-lan] " Florian Fainelli
2018-12-03 18:55 ` [PATCH net-next v3 2/2] ixgbe: use mii_bus to handle MII related ioctls Steve Douthit
2018-12-03 18:55 ` [Intel-wired-lan] " Steve Douthit
2018-12-03 19:01 ` Andrew Lunn
2018-12-03 19:01 ` [Intel-wired-lan] " Andrew Lunn
2018-12-03 19:07 ` Florian Fainelli
2018-12-03 19:07 ` [Intel-wired-lan] " Florian Fainelli
2018-12-03 20:14 ` [PATCH net-next v4 0/2] Add mii_bus to ixgbe driver for dsa devs Steve Douthit
2018-12-03 20:14 ` [Intel-wired-lan] " Steve Douthit
2018-12-03 20:15 ` [PATCH net-next v4 1/2] ixgbe: register a mdiobus Steve Douthit
2018-12-03 20:15 ` [Intel-wired-lan] " Steve Douthit
2018-12-04 16:58 ` Bowers, AndrewX
2018-12-04 16:58 ` [Intel-wired-lan] " Bowers, AndrewX
2018-12-03 20:15 ` [PATCH net-next v4 2/2] ixgbe: use mii_bus to handle MII related ioctls Steve Douthit
2018-12-03 20:15 ` [Intel-wired-lan] " Steve Douthit
2018-12-04 16:59 ` Bowers, AndrewX
2018-12-04 16:59 ` [Intel-wired-lan] " Bowers, AndrewX
2018-12-03 20:51 ` [PATCH net-next v4 0/2] Add mii_bus to ixgbe driver for dsa devs Florian Fainelli
2018-12-03 20:51 ` [Intel-wired-lan] " Florian Fainelli
2018-12-03 23:42 ` Steve Douthit
2018-12-03 23:42 ` [Intel-wired-lan] " Steve Douthit
2018-12-03 23:46 ` Florian Fainelli
2018-12-03 23:46 ` [Intel-wired-lan] " Florian Fainelli
2018-12-04 10:40 ` Andrew Lunn
2018-12-04 10:40 ` [Intel-wired-lan] " Andrew Lunn
2018-12-04 16:02 ` Steve Douthit
2018-12-04 16:02 ` [Intel-wired-lan] " Steve Douthit
2018-12-06 15:50 ` [PATCH net-next v5 " Steve Douthit
2018-12-06 15:50 ` [Intel-wired-lan] " Steve Douthit
2018-12-06 15:50 ` [PATCH net-next v5 1/2] ixgbe: register a mdiobus Steve Douthit
2018-12-06 15:50 ` [Intel-wired-lan] " Steve Douthit
2018-12-06 15:50 ` [PATCH net-next v5 2/2] ixgbe: use mii_bus to handle MII related ioctls Steve Douthit
2018-12-06 15:50 ` [Intel-wired-lan] " Steve Douthit
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