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From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
To: Antoine Tenart <antoine.tenart@bootlin.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>,
	davem@davemloft.net, kishon@ti.com, linux@armlinux.org.uk,
	gregory.clement@bootlin.com, andrew@lunn.ch,
	jason@lakedaemon.net, sebastian.hesselbarth@gmail.com,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	maxime.chevallier@bootlin.com, miquel.raynal@bootlin.com,
	nadavh@marvell.com, stefanc@marvell.com, ymarkman@marvell.com,
	mw@semihalf.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH net-next v2 02/13] net: phy: sfp: handle non-wired SFP connectors
Date: Sat, 5 May 2018 17:39:45 +0200	[thread overview]
Message-ID: <20180505173945.0754d0df@windsurf> (raw)
In-Reply-To: <20180504172337.GC13899@kwain>

Hello,

On Fri, 4 May 2018 19:23:37 +0200, Antoine Tenart wrote:

> On Fri, May 04, 2018 at 10:04:48AM -0700, Florian Fainelli wrote:
> > On 05/04/2018 06:56 AM, Antoine Tenart wrote:  
> > > SFP connectors can be solder on a board without having any of their pins
> > > (LOS, i2c...) wired. In such cases the SFP link state cannot be guessed,
> > > and the overall link status reporting is left to other layers.
> > > 
> > > In order to achieve this, a new SFP_DEV status is added, named UNKNOWN.
> > > This mode is set when it is not possible for the SFP code to get the
> > > link status and as a result the link status is reported to be always UP
> > > from the SFP point of view.  
> > 
> > Why represent the SFP in Device Tree then? Why not just declare this is
> > a fixed link which would avoid having to introduce this "unknown" state.  
> 
> The other solution would have been to represent this as a fixed-link.
> But such a representation would report the link as being up all the
> time, which is something we wanted to avoid as the GoP in PPv2 can
> report some link status. This is achieved using SFP+phylink+PPv2.
> 
> And representing the SFP cage in the device tree, although it's a
> "dummy" one, helps describing the hardware.

Just to add to this: the board physically has a SFP cage, and a cable
can be connected to it, or not. So it is absolutely not a fixed link
(cable can be connected or not) and it really is a SFP cage.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

  reply	other threads:[~2018-05-05 15:39 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-04 13:56 [PATCH net-next v2 00/13] net: mvpp2: phylink conversion Antoine Tenart
2018-05-04 13:56 ` [PATCH net-next v2 01/13] net: phy: sfp: make the i2c-bus property really optional Antoine Tenart
2018-05-04 17:03   ` Florian Fainelli
2018-05-04 17:19     ` Antoine Tenart
2018-05-04 13:56 ` [PATCH net-next v2 02/13] net: phy: sfp: handle non-wired SFP connectors Antoine Tenart
2018-05-04 17:04   ` Florian Fainelli
2018-05-04 17:17     ` Andrew Lunn
2018-05-04 17:23     ` Antoine Tenart
2018-05-05 15:39       ` Thomas Petazzoni [this message]
2018-05-05 17:48         ` Andrew Lunn
2018-05-08 11:52   ` Russell King - ARM Linux
2018-05-14  9:26     ` Antoine Tenart
2018-05-04 13:56 ` [PATCH net-next v2 03/13] net: phy: sfp: warn the user when no tx_disable pin is available Antoine Tenart
2018-05-04 17:07   ` Florian Fainelli
2018-05-04 17:14     ` Andrew Lunn
2018-05-05 20:38       ` Florian Fainelli
2018-05-05 20:52         ` Andrew Lunn
2018-05-08 12:45           ` Russell King - ARM Linux
2018-05-08 11:53   ` Russell King - ARM Linux
2018-05-04 13:56 ` [PATCH net-next v2 04/13] net: mvpp2: align the ethtool ops definition Antoine Tenart
2018-05-04 13:56 ` [PATCH net-next v2 05/13] net: mvpp2: phylink support Antoine Tenart
2018-05-04 13:56 ` [PATCH net-next v2 06/13] phy: add 2.5G SGMII mode to the phy_mode enum Antoine Tenart
2018-05-08 12:34   ` Russell King - ARM Linux
2018-05-14  8:37     ` Antoine Tenart
2018-05-04 13:56 ` [PATCH net-next v2 07/13] phy: cp110-comphy: 2.5G SGMII mode Antoine Tenart
2018-05-04 13:56 ` [PATCH net-next v2 08/13] net: mvpp2: 1000baseX support Antoine Tenart
2018-05-04 13:56 ` [PATCH net-next v2 09/13] net: mvpp2: 2500baseX support Antoine Tenart
2018-05-04 13:56 ` [PATCH net-next v2 10/13] arm64: dts: marvell: mcbin: add 10G SFP support Antoine Tenart
2018-05-04 13:56 ` [PATCH net-next v2 11/13] arm64: dts: marvell: mcbin: enable the fourth network interface Antoine Tenart
2018-05-04 13:56 ` [PATCH net-next v2 12/13] arm64: dts: marvell: 7040-db: describe the 10G SFP cage Antoine Tenart
2018-05-04 13:56 ` [PATCH net-next v2 13/13] arm64: dts: marvell: 8040-db: describe the 10G SFP cages Antoine Tenart
2018-05-08  3:18 ` [PATCH net-next v2 00/13] net: mvpp2: phylink conversion David Miller

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