Hi, Anand,
Attempt to force link speed to 40000 ends up in the following:
# ethtool -s p2p1 speed 40000
Cannot set new settings: Operation not supported
not setting speed
# dmesg -c
mlx4_en_QUERY_PORT: ENTER
mlx4_en_QUERY_PORT-105: Link speed reported @10GBPS
mlx4_en_QUERY_PORT: ENTER
mlx4_en_QUERY_PORT-105: Link speed reported @10GBPS
mlx4_en: p2p1: Changing port state properties (auto-negotiation , speed/duplex) is not supported. Current: auto-negotiation=0 speed/duplex=10000/FULL
Driver reports non-supported operations for the port (first four lines my debug prink's from the driver).
Regards,
Philip