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