On Wed, Jan 22, 2025 at 06:55:17PM +0000, Russell King (Oracle) wrote: > On Wed, Jan 22, 2025 at 06:42:46PM +0100, Maxime Chevallier wrote: > > When referring to BaseT ethernet, we are most of the time thinking of > > BaseT4 ethernet on Cat5/6/7 cables. This is therefore BaseT4, although > > BaseT4 is also possible for 100BaseTX. This is even more true now that > > we have a special __LINK_MODE_LANES_T1 mode especially for Single Pair > > ethernet. > > > > Mark BaseT as being a 4-lanes mode. > > This is a problem: > > 1.4.50 10BASE-T: IEEE 802.3 Physical Layer specification for a 10 Mb/s > CSMA/CD local area network over two pairs of twisted-pair telephone > wire. (See IEEE Std 802.3, Clause 14.) > > Then we have the 100BASE-T* family, which can be T1, T2, T4 or TX. > T1 is over a single balanced twisted pair. T2 is over two pairs of > Cat 3 or better. T4 is over four pairs of Cat3/4/5. > > The common 100BASE-T* type is TX, which is over two pairs of Cat5. > This is sadly what the ethtool 100baseT link modes are used to refer > to. > > We do have a separate link mode for 100baseT1, but not 100baseT4. > > So, these ethtool modes that are of the form baseT so far are > describing generally two pairs, one pair in each direction. (T1 is > a single pair that is bidirectional.) > > It's only once we get to 1000BASE-T (1000baseT) that we get to an > ethtool link mode that has four lanes in a bidirectional fashion. > > So, simply redefining this ends up changing 10baseT and 100baseT from > a single lane in each direction to four lanes (and is a "lane" here > defined as the total number of pairs used for communication in both > directions, or the total number of lanes used in either direction. > > Hence, I'm not sure this makes sense. Looking at patch 2, I don't see why you need patch 1. It's not really improving the situation. Before the patch, the number of lanes for some BASE-T is wrong. After the patch, the number of lanes for some BASE-T is also wrong - just a different subset. I think you should drop this patch and just have patch 2. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
