From: Danielle Ratson <daniel...@nvidia.com>

Some speeds can be achieved with different number of lanes. For example,
100Gbps can be achieved using two lanes of 50Gbps or four lanes of
25Gbps. This patch set adds a new selector that allows ethtool to
advertise link modes according to their number of lanes and also force a
specific number of lanes when autonegotiation is off.

Advertising all link modes with a speed of 100Gbps that use two lanes:

$ ethtool -s swp1 speed 100000 lanes 2 autoneg on

Forcing a speed of 100Gbps using four lanes:

$ ethtool -s swp1 speed 100000 lanes 4 autoneg off

Patch set overview:

Patch #1 allows user space to configure the desired number of lanes.

Patch #2-#3 adjusts ethtool to dump to user space the number of lanes
currently in use.

Patches #4-#6 add support for lanes configuration in mlxsw.

Patch #7 adds a selftest.

v2:
        * Patch #1: Remove ETHTOOL_LANES defines and simply use a number
          instead.
        * Patches #2,#6: Pass link mode from driver to ethtool instead
        * of the parameters themselves.
        * Patch #5: Add an actual width field for spectrum-2 link modes
          in order to set the suitable link mode when lanes parameter is
          passed.
        * Patch #6: Changed lanes to be unsigned in
          'struct link_mode_info'.
        * Patch #7: Remove the test for recieving max_width when lanes
        * is not set by user. When not setting lanes, we don't promise
          anything regarding what number of lanes will be chosen.

Danielle Ratson (7):
  ethtool: Extend link modes settings uAPI with lanes
  ethtool: Get link mode in use instead of speed and duplex parameters
  ethtool: Expose the number of lanes in use
  mlxsw: ethtool: Remove max lanes filtering
  mlxsw: ethtool: Add support for setting lanes when autoneg is off
  mlxsw: ethtool: Pass link mode in use to ethtool
  net: selftests: Add lanes setting test

 Documentation/networking/ethtool-netlink.rst  |  12 +-
 .../net/ethernet/mellanox/mlxsw/spectrum.h    |  13 +-
 .../mellanox/mlxsw/spectrum_ethtool.c         | 168 +++++----
 include/linux/ethtool.h                       |   5 +
 include/uapi/linux/ethtool.h                  |   4 +
 include/uapi/linux/ethtool_netlink.h          |   1 +
 net/ethtool/linkmodes.c                       | 321 +++++++++++-------
 net/ethtool/netlink.h                         |   2 +-
 .../selftests/net/forwarding/ethtool_lanes.sh | 186 ++++++++++
 .../selftests/net/forwarding/ethtool_lib.sh   |  34 ++
 tools/testing/selftests/net/forwarding/lib.sh |  28 ++
 11 files changed, 570 insertions(+), 204 deletions(-)
 create mode 100755 tools/testing/selftests/net/forwarding/ethtool_lanes.sh

-- 
2.26.2

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