debugfs entries for RRoCE general CC parameters must be exposed only when they are supported, otherwise when accessing them there may be a syndrome error in kernel log, for example: $ cat /sys/kernel/debug/mlx5/0000:08:00.1/cc_params/rtt_resp_dscp cat: '/sys/kernel/debug/mlx5/0000:08:00.1/cc_params/rtt_resp_dscp': Invalid argument $ dmesg mlx5_core 0000:08:00.1: mlx5_cmd_out_err:805:(pid 1253): QUERY_CONG_PARAMS(0x824) op_mod(0x0) failed, status bad parameter(0x3), syndrome (0x325a82), err(-22) Fixes: 66fb1d5df6ac ("IB/mlx5: Extend debug control for CC parameters") Reviewed-by: Edward Srouji <edwards@nvidia.com> Signed-off-by: Mark Zhang <markzhang@nvidia.com> Link: https://lore.kernel.org/r/e7ade70bad52b7468bdb1de4d41d5fad70c8b71c.1706433934.git.leon@kernel.org Signed-off-by: Leon Romanovsky <leon@kernel.org>