On Tue, Mar 16, 2021 at 13:24, Vladimir Oltean <olte...@gmail.com> wrote: > From: Vladimir Oltean <vladimir.olt...@nxp.com> > > Add a short summary of the methods that a driver writer must implement > for offloading a link aggregation group, and what is still missing. > > Cc: Tobias Waldekranz <tob...@waldekranz.com> > Signed-off-by: Vladimir Oltean <vladimir.olt...@nxp.com> > Reviewed-by: Florian Fainelli <f.faine...@gmail.com> > ---
Reviewed-by: Tobias Waldekranz <tob...@waldekranz.com> > Documentation/networking/dsa/dsa.rst | 33 ++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/Documentation/networking/dsa/dsa.rst > b/Documentation/networking/dsa/dsa.rst > index af604fe976b3..e8576e81735c 100644 > --- a/Documentation/networking/dsa/dsa.rst > +++ b/Documentation/networking/dsa/dsa.rst > @@ -724,6 +724,39 @@ Bridge VLAN filtering > function that the driver has to call for each MAC address known to be > behind > the given port. A switchdev object is used to carry the VID and MDB info. > > +Link aggregation > +---------------- > + > +Link aggregation is implemented in the Linux networking stack by the bonding > +and team drivers, which are modeled as virtual, stackable network interfaces. > +DSA is capable of offloading a link aggregation group (LAG) to hardware that > +supports the feature, and supports bridging between physical ports and LAGs, > +as well as between LAGs. A bonding/team interface which holds multiple > physical > +ports constitutes a logical port, although DSA has no explicit concept of a > +logical port at the moment. Due to this, events where a LAG joins/leaves a > +bridge are treated as if all individual physical ports that are members of > that > +LAG join/leave the bridge. Switchdev port attributes (VLAN filtering, STP > +state, etc) and objects (VLANs, MDB entries) offloaded to a LAG as bridge > port > +are treated similarly: DSA offloads the same switchdev object / port > attribute > +on all members of the LAG. Static bridge FDB entries on a LAG are not yet > +supported, since the DSA driver API does not have the concept of a logical > port > +ID. > + > +- ``port_lag_join``: function invoked when a given switch port is added to a > + LAG. The driver may return ``-EOPNOTSUPP``, and in this case, DSA will fall > + back to a software implementation where all traffic from this port is sent > to > + the CPU. > +- ``port_lag_leave``: function invoked when a given switch port leaves a LAG > + and returns to operation as a standalone port. > +- ``port_lag_change``: function invoked when the link state of any member of > + the LAG changes, and the hashing function needs rebalancing to only make > use > + of the subset of physical LAG member ports that are up. > + > +Drivers that benefit from having an ID associated with each offloaded LAG > +can optionally populate ``ds->num_lag_ids`` from the > ``dsa_switch_ops::setup`` > +method. The LAG ID associated with a bonding/team interface can then be > +retrieved by a DSA switch driver using the ``dsa_lag_id`` function. > + > TODO > ==== > > -- > 2.25.1
