Currently, when auto negotiation is on, the user can advertise all the
linkmodes which correspond to a specific speed, but does not have a
similar selector for the number of lanes. This is significant when a
specific speed can be achieved using different number of lanes. For
example, 2x50 or 4x25.
Add 'ETHTOOL_A_LINKMODES_LANES' attribute and expand 'struct
ethtool_link_settings' with lanes field in order to implement a new
lanes-selector that will enable the user to advertise a specific number
of lanes as well.
When auto negotiation is off, lanes parameter can be forced only if the
driver supports it. Add a capability bit in 'struct ethtool_ops' that
allows ethtool know if the driver can handle the lanes parameter when
auto negotiation is off, so if it does not, an error message will be
returned when trying to set lanes.
Example:
$ ethtool -s swp1 lanes 4
$ ethtool swp1
Settings for swp1:
Supported ports: [ FIBRE ]
Supported link modes: 1000baseKX/Full
10000baseKR/Full
40000baseCR4/Full
40000baseSR4/Full
40000baseLR4/Full
25000baseCR/Full
25000baseSR/Full
50000baseCR2/Full
100000baseSR4/Full
100000baseCR4/Full
Supported pause frame use: Symmetric Receive-only
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 40000baseCR4/Full
40000baseSR4/Full
40000baseLR4/Full
100000baseSR4/Full
100000baseCR4/Full
Advertised pause frame use: No
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Speed: Unknown!
Duplex: Unknown! (255)
Auto-negotiation: on
Port: Direct Attach Copper
PHYAD: 0
Transceiver: internal
Link detected: no
Signed-off-by: Danielle Ratson <danieller@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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