From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Andrew Lunn <andrew@lunn.ch>
Cc: Antoine Tenart <antoine.tenart@bootlin.com>,
davem@davemloft.net, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, thomas.petazzoni@bootlin.com,
maxime.chevallier@bootlin.com, gregory.clement@bootlin.com,
miquel.raynal@bootlin.com, nadavh@marvell.com,
stefanc@marvell.com, ymarkman@marvell.com, mw@semihalf.com
Subject: Re: [PATCH net-next 1/2] net: phy: sfp: make the i2c-bus property really optional
Date: Thu, 17 May 2018 16:01:55 +0100 [thread overview]
Message-ID: <20180517150155.GB17671@n2100.armlinux.org.uk> (raw)
In-Reply-To: <20180517124127.GG8547@lunn.ch>
On Thu, May 17, 2018 at 02:41:28PM +0200, Andrew Lunn wrote:
> On Thu, May 17, 2018 at 10:29:06AM +0200, Antoine Tenart wrote:
> > The SFF,SFP documentation is clear about making all the DT properties,
> > with the exception of the compatible, optional. In practice this is not
> > the case and without an i2c-bus property provided the SFP code will
> > throw NULL pointer exceptions.
> >
> > This patch is an attempt to fix this.
>
> Hi Antoine, Russell
>
> How usable is an SFF/SFP module without access to the i2c EEPROM? I
> guess this comes down to link speed. Can it be manually configured?
While we can support forcing the speed/duplex through ethtool, there
is no obvious facility via ethtool to set the protocol currently (eg,
SGMII vs 1000base-X). There is, however, the possibility to use the
advertise mask to determine which mode we should be using, but that's
awkward to deal with via ethtool as ethtool wants a hex mask, which
really isn't user friendly.
The protocol matters - for example, a copper SFP module will typically
want to use SGMII, and if it encounters 1000base-X on the other side,
the PHY won't pass data because it will believe that the link to the
MAC is down.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up
According to speedtest.net: 8.21Mbps down 510kbps up
next prev parent reply other threads:[~2018-05-17 15:02 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-17 8:29 [PATCH net-next 0/2] net: sfp: small improvements Antoine Tenart
2018-05-17 8:29 ` [PATCH net-next 1/2] net: phy: sfp: make the i2c-bus property really optional Antoine Tenart
2018-05-17 12:41 ` Andrew Lunn
2018-05-17 12:56 ` Antoine Tenart
2018-05-17 13:04 ` Andrew Lunn
2018-05-17 13:13 ` Antoine Tenart
2018-05-17 15:08 ` Russell King - ARM Linux
2018-05-17 15:01 ` Russell King - ARM Linux [this message]
2018-05-17 8:29 ` [PATCH net-next 2/2] net: phy: sfp: warn the user when no tx_disable pin is available Antoine Tenart
2018-05-21 15:51 ` [PATCH net-next 0/2] net: sfp: small improvements David Miller
2018-05-22 9:24 ` Antoine Tenart
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