net/enic: fix filter mode detection

[ upstream commit fb92745 ]

vnic_dev_capable_filter_mode() currently fails when
CMD_CAPABILITY(CMD_ADD_FILTER) returns ERR_EPERM. In turn, this
failure causes the driver initialization to fail.

But, firmware may legitimately return ERR_EPERM. For example, VF vNIC
returns ERR_EPERM when it does not support filtering at all. So, treat
ERR_EPERM as "no filtering available" instead of an unexpected error.

Fixes: 322b355 ("net/enic/base: bring NIC interface functions up to date")

Signed-off-by: Hyong Youb Kim <hyonkim@cisco.com>
Reviewed-by: John Daley <johndale@cisco.com>

drivers/net/enic/base/vnic_dev.c

@@ -570,8 +570,8 @@ static int vnic_dev_flowman_enable(struct vnic_dev *vdev, u32 *mode,
 	return 1;
 }
 
-/*  Determine the "best" filtering mode VIC is capaible of. Returns one of 4
- *  value or 0 on error:
+/*  Determine the "best" filtering mode VIC is capable of. Returns one of 4
+ *  value or 0 if filtering is unavailble:
  *	FILTER_FLOWMAN- flowman api capable
  *	FILTER_DPDK_1- advanced filters availabile
  *	FILTER_USNIC_IP_FLAG - advanced filters but with the restriction that
@@ -606,6 +606,14 @@ int vnic_dev_capable_filter_mode(struct vnic_dev *vdev, u32 *mode,
 		args[0] = CMD_ADD_FILTER;
 		args[1] = 0;
 		err = vnic_dev_cmd_args(vdev, CMD_CAPABILITY, args, 2, 1000);
+		/*
+		 * ERR_EPERM may be returned if, for example, vNIC is
+		 * on a VF. It simply means no filtering is available
+		 */
+		if (err == -ERR_EPERM) {
+			*mode = 0;
+			return 0;
+		}
 		if (err)
 			return err;
 		max_level = args[1];