Merge branch 'support-setting-lanes-via-ethtool'

Danielle Ratson says:

====================
Support setting lanes via ethtool

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 patchset 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
====================

Link: https://lore.kernel.org/r/20210202180612.325099-1-danieller@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/networking/ethtool-netlink.rst

@@ -431,16 +431,17 @@ Request contents:
   ``ETHTOOL_A_LINKMODES_SPEED``               u32     link speed (Mb/s)
   ``ETHTOOL_A_LINKMODES_DUPLEX``              u8      duplex mode
   ``ETHTOOL_A_LINKMODES_MASTER_SLAVE_CFG``    u8      Master/slave port mode
+  ``ETHTOOL_A_LINKMODES_LANES``               u32     lanes
   ==========================================  ======  ==========================
 
 ``ETHTOOL_A_LINKMODES_OURS`` bit set allows setting advertised link modes. If
 autonegotiation is on (either set now or kept from before), advertised modes
 are not changed (no ``ETHTOOL_A_LINKMODES_OURS`` attribute) and at least one
-of speed and duplex is specified, kernel adjusts advertised modes to all
-supported modes matching speed, duplex or both (whatever is specified). This
-autoselection is done on ethtool side with ioctl interface, netlink interface
-is supposed to allow requesting changes without knowing what exactly kernel
-supports.
+of speed, duplex and lanes is specified, kernel adjusts advertised modes to all
+supported modes matching speed, duplex, lanes or all (whatever is specified).
+This autoselection is done on ethtool side with ioctl interface, netlink
+interface is supposed to allow requesting changes without knowing what exactly
+kernel supports.
 
 
 LINKSTATE_GET

drivers/net/ethernet/mellanox/mlxsw/spectrum.h

@@ -328,15 +328,16 @@ struct mlxsw_sp_port_type_speed_ops {
 					 u32 ptys_eth_proto,
 					 struct ethtool_link_ksettings *cmd);
 	void (*from_ptys_link)(struct mlxsw_sp *mlxsw_sp, u32 ptys_eth_proto,
-			       u8 width, unsigned long *mode);
+			       unsigned long *mode);
 	u32 (*from_ptys_speed)(struct mlxsw_sp *mlxsw_sp, u32 ptys_eth_proto);
-	void (*from_ptys_speed_duplex)(struct mlxsw_sp *mlxsw_sp,
-				       bool carrier_ok, u32 ptys_eth_proto,
-				       struct ethtool_link_ksettings *cmd);
+	void (*from_ptys_link_mode)(struct mlxsw_sp *mlxsw_sp,
+				    bool carrier_ok, u32 ptys_eth_proto,
+				    struct ethtool_link_ksettings *cmd);
 	int (*ptys_max_speed)(struct mlxsw_sp_port *mlxsw_sp_port, u32 *p_max_speed);
-	u32 (*to_ptys_advert_link)(struct mlxsw_sp *mlxsw_sp, u8 width,
+	u32 (*to_ptys_advert_link)(struct mlxsw_sp *mlxsw_sp,
+				   const struct ethtool_link_ksettings *cmd);
+	u32 (*to_ptys_speed_lanes)(struct mlxsw_sp *mlxsw_sp, u8 width,
 				   const struct ethtool_link_ksettings *cmd);
-	u32 (*to_ptys_speed)(struct mlxsw_sp *mlxsw_sp, u8 width, u32 speed);
 	void (*reg_ptys_eth_pack)(struct mlxsw_sp *mlxsw_sp, char *payload,
 				  u8 local_port, u32 proto_admin, bool autoneg);
 	void (*reg_ptys_eth_unpack)(struct mlxsw_sp *mlxsw_sp, char *payload,

include/linux/ethtool.h

@@ -128,6 +128,8 @@ struct ethtool_link_ksettings {
 		__ETHTOOL_DECLARE_LINK_MODE_MASK(advertising);
 		__ETHTOOL_DECLARE_LINK_MODE_MASK(lp_advertising);
 	} link_modes;
+	u32	lanes;
+	enum ethtool_link_mode_bit_indices link_mode;
 };
 
 /**
@@ -265,6 +267,8 @@ struct ethtool_pause_stats {
 
 /**
  * struct ethtool_ops - optional netdev operations
+ * @cap_link_lanes_supported: indicates if the driver supports lanes
+ *	parameter.
  * @supported_coalesce_params: supported types of interrupt coalescing.
  * @get_drvinfo: Report driver/device information.  Should only set the
  *	@driver, @version, @fw_version and @bus_info fields.  If not
@@ -420,6 +424,7 @@ struct ethtool_pause_stats {
  * of the generic netdev features interface.
  */
 struct ethtool_ops {
+	u32     cap_link_lanes_supported:1;
 	u32	supported_coalesce_params;
 	void	(*get_drvinfo)(struct net_device *, struct ethtool_drvinfo *);
 	int	(*get_regs_len)(struct net_device *);

include/uapi/linux/ethtool_netlink.h

@@ -227,6 +227,7 @@ enum {
 	ETHTOOL_A_LINKMODES_DUPLEX,		/* u8 */
 	ETHTOOL_A_LINKMODES_MASTER_SLAVE_CFG,	/* u8 */
 	ETHTOOL_A_LINKMODES_MASTER_SLAVE_STATE,	/* u8 */
+	ETHTOOL_A_LINKMODES_LANES,		/* u32 */
 
 	/* add new constants above here */
 	__ETHTOOL_A_LINKMODES_CNT,

net/ethtool/common.c

@@ -198,6 +198,153 @@ const char link_mode_names[][ETH_GSTRING_LEN] = {
 };
 static_assert(ARRAY_SIZE(link_mode_names) == __ETHTOOL_LINK_MODE_MASK_NBITS);
 
+#define __LINK_MODE_LANES_CR		1
+#define __LINK_MODE_LANES_CR2		2
+#define __LINK_MODE_LANES_CR4		4
+#define __LINK_MODE_LANES_CR8		8
+#define __LINK_MODE_LANES_DR		1
+#define __LINK_MODE_LANES_DR2		2
+#define __LINK_MODE_LANES_DR4		4
+#define __LINK_MODE_LANES_DR8		8
+#define __LINK_MODE_LANES_KR		1
+#define __LINK_MODE_LANES_KR2		2
+#define __LINK_MODE_LANES_KR4		4
+#define __LINK_MODE_LANES_KR8		8
+#define __LINK_MODE_LANES_SR		1
+#define __LINK_MODE_LANES_SR2		2
+#define __LINK_MODE_LANES_SR4		4
+#define __LINK_MODE_LANES_SR8		8
+#define __LINK_MODE_LANES_ER		1
+#define __LINK_MODE_LANES_KX		1
+#define __LINK_MODE_LANES_KX4		4
+#define __LINK_MODE_LANES_LR		1
+#define __LINK_MODE_LANES_LR4		4
+#define __LINK_MODE_LANES_LR4_ER4	4
+#define __LINK_MODE_LANES_LR_ER_FR	1
+#define __LINK_MODE_LANES_LR2_ER2_FR2	2
+#define __LINK_MODE_LANES_LR4_ER4_FR4	4
+#define __LINK_MODE_LANES_LR8_ER8_FR8	8
+#define __LINK_MODE_LANES_LRM		1
+#define __LINK_MODE_LANES_MLD2		2
+#define __LINK_MODE_LANES_T		1
+#define __LINK_MODE_LANES_T1		1
+#define __LINK_MODE_LANES_X		1
+#define __LINK_MODE_LANES_FX		1
+
+#define __DEFINE_LINK_MODE_PARAMS(_speed, _type, _duplex)	\
+	[ETHTOOL_LINK_MODE(_speed, _type, _duplex)] = {		\
+		.speed  = SPEED_ ## _speed, \
+		.lanes  = __LINK_MODE_LANES_ ## _type, \
+		.duplex	= __DUPLEX_ ## _duplex \
+	}
+#define __DUPLEX_Half DUPLEX_HALF
+#define __DUPLEX_Full DUPLEX_FULL
+#define __DEFINE_SPECIAL_MODE_PARAMS(_mode) \
+	[ETHTOOL_LINK_MODE_ ## _mode ## _BIT] = { \
+		.speed	= SPEED_UNKNOWN, \
+		.lanes	= 0, \
+		.duplex	= DUPLEX_UNKNOWN, \
+	}
+
+const struct link_mode_info link_mode_params[] = {
+	__DEFINE_LINK_MODE_PARAMS(10, T, Half),
+	__DEFINE_LINK_MODE_PARAMS(10, T, Full),
+	__DEFINE_LINK_MODE_PARAMS(100, T, Half),
+	__DEFINE_LINK_MODE_PARAMS(100, T, Full),
+	__DEFINE_LINK_MODE_PARAMS(1000, T, Half),
+	__DEFINE_LINK_MODE_PARAMS(1000, T, Full),
+	__DEFINE_SPECIAL_MODE_PARAMS(Autoneg),
+	__DEFINE_SPECIAL_MODE_PARAMS(TP),
+	__DEFINE_SPECIAL_MODE_PARAMS(AUI),
+	__DEFINE_SPECIAL_MODE_PARAMS(MII),
+	__DEFINE_SPECIAL_MODE_PARAMS(FIBRE),
+	__DEFINE_SPECIAL_MODE_PARAMS(BNC),
+	__DEFINE_LINK_MODE_PARAMS(10000, T, Full),
+	__DEFINE_SPECIAL_MODE_PARAMS(Pause),
+	__DEFINE_SPECIAL_MODE_PARAMS(Asym_Pause),
+	__DEFINE_LINK_MODE_PARAMS(2500, X, Full),
+	__DEFINE_SPECIAL_MODE_PARAMS(Backplane),
+	__DEFINE_LINK_MODE_PARAMS(1000, KX, Full),
+	__DEFINE_LINK_MODE_PARAMS(10000, KX4, Full),
+	__DEFINE_LINK_MODE_PARAMS(10000, KR, Full),
+	[ETHTOOL_LINK_MODE_10000baseR_FEC_BIT] = {
+		.speed	= SPEED_10000,
+		.duplex = DUPLEX_FULL,
+	},
+	__DEFINE_LINK_MODE_PARAMS(20000, MLD2, Full),
+	__DEFINE_LINK_MODE_PARAMS(20000, KR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(40000, KR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(40000, CR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(40000, SR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(40000, LR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(56000, KR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(56000, CR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(56000, SR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(56000, LR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(25000, CR, Full),
+	__DEFINE_LINK_MODE_PARAMS(25000, KR, Full),
+	__DEFINE_LINK_MODE_PARAMS(25000, SR, Full),
+	__DEFINE_LINK_MODE_PARAMS(50000, CR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(50000, KR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, KR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, SR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, CR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, LR4_ER4, Full),
+	__DEFINE_LINK_MODE_PARAMS(50000, SR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(1000, X, Full),
+	__DEFINE_LINK_MODE_PARAMS(10000, CR, Full),
+	__DEFINE_LINK_MODE_PARAMS(10000, SR, Full),
+	__DEFINE_LINK_MODE_PARAMS(10000, LR, Full),
+	__DEFINE_LINK_MODE_PARAMS(10000, LRM, Full),
+	__DEFINE_LINK_MODE_PARAMS(10000, ER, Full),
+	__DEFINE_LINK_MODE_PARAMS(2500, T, Full),
+	__DEFINE_LINK_MODE_PARAMS(5000, T, Full),
+	__DEFINE_SPECIAL_MODE_PARAMS(FEC_NONE),
+	__DEFINE_SPECIAL_MODE_PARAMS(FEC_RS),
+	__DEFINE_SPECIAL_MODE_PARAMS(FEC_BASER),
+	__DEFINE_LINK_MODE_PARAMS(50000, KR, Full),
+	__DEFINE_LINK_MODE_PARAMS(50000, SR, Full),
+	__DEFINE_LINK_MODE_PARAMS(50000, CR, Full),
+	__DEFINE_LINK_MODE_PARAMS(50000, LR_ER_FR, Full),
+	__DEFINE_LINK_MODE_PARAMS(50000, DR, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, KR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, SR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, CR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, LR2_ER2_FR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, DR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(200000, KR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(200000, SR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(200000, LR4_ER4_FR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(200000, DR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(200000, CR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(100, T1, Full),
+	__DEFINE_LINK_MODE_PARAMS(1000, T1, Full),
+	__DEFINE_LINK_MODE_PARAMS(400000, KR8, Full),
+	__DEFINE_LINK_MODE_PARAMS(400000, SR8, Full),
+	__DEFINE_LINK_MODE_PARAMS(400000, LR8_ER8_FR8, Full),
+	__DEFINE_LINK_MODE_PARAMS(400000, DR8, Full),
+	__DEFINE_LINK_MODE_PARAMS(400000, CR8, Full),
+	__DEFINE_SPECIAL_MODE_PARAMS(FEC_LLRS),
+	__DEFINE_LINK_MODE_PARAMS(100000, KR, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, SR, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, LR_ER_FR, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, DR, Full),
+	__DEFINE_LINK_MODE_PARAMS(100000, CR, Full),
+	__DEFINE_LINK_MODE_PARAMS(200000, KR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(200000, SR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(200000, LR2_ER2_FR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(200000, DR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(200000, CR2, Full),
+	__DEFINE_LINK_MODE_PARAMS(400000, KR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(400000, SR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(400000, LR4_ER4_FR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(400000, DR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(400000, CR4, Full),
+	__DEFINE_LINK_MODE_PARAMS(100, FX, Half),
+	__DEFINE_LINK_MODE_PARAMS(100, FX, Full),
+};
+static_assert(ARRAY_SIZE(link_mode_params) == __ETHTOOL_LINK_MODE_MASK_NBITS);
+
 const char netif_msg_class_names[][ETH_GSTRING_LEN] = {
 	[NETIF_MSG_DRV_BIT]		= "drv",
 	[NETIF_MSG_PROBE_BIT]		= "probe",

net/ethtool/common.h

@@ -14,6 +14,12 @@
 
 #define __SOF_TIMESTAMPING_CNT (const_ilog2(SOF_TIMESTAMPING_LAST) + 1)
 
+struct link_mode_info {
+	int				speed;
+	u8				lanes;
+	u8				duplex;
+};
+
 extern const char
 netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN];
 extern const char
@@ -23,6 +29,7 @@ tunable_strings[__ETHTOOL_TUNABLE_COUNT][ETH_GSTRING_LEN];
 extern const char
 phy_tunable_strings[__ETHTOOL_PHY_TUNABLE_COUNT][ETH_GSTRING_LEN];
 extern const char link_mode_names[][ETH_GSTRING_LEN];
+extern const struct link_mode_info link_mode_params[];
 extern const char netif_msg_class_names[][ETH_GSTRING_LEN];
 extern const char wol_mode_names[][ETH_GSTRING_LEN];
 extern const char sof_timestamping_names[][ETH_GSTRING_LEN];

net/ethtool/ioctl.c

@@ -426,13 +426,29 @@ struct ethtool_link_usettings {
 int __ethtool_get_link_ksettings(struct net_device *dev,
 				 struct ethtool_link_ksettings *link_ksettings)
 {
+	const struct link_mode_info *link_info;
+	int err;
+
 	ASSERT_RTNL();
 
 	if (!dev->ethtool_ops->get_link_ksettings)
 		return -EOPNOTSUPP;
 
 	memset(link_ksettings, 0, sizeof(*link_ksettings));
-	return dev->ethtool_ops->get_link_ksettings(dev, link_ksettings);
+
+	link_ksettings->link_mode = -1;
+	err = dev->ethtool_ops->get_link_ksettings(dev, link_ksettings);
+	if (err)
+		return err;
+
+	if (link_ksettings->link_mode != -1) {
+		link_info = &link_mode_params[link_ksettings->link_mode];
+		link_ksettings->base.speed = link_info->speed;
+		link_ksettings->lanes = link_info->lanes;
+		link_ksettings->base.duplex = link_info->duplex;
+	}
+
+	return 0;
 }
 EXPORT_SYMBOL(__ethtool_get_link_ksettings);
 

net/ethtool/netlink.h

@@ -351,7 +351,7 @@ extern const struct nla_policy ethnl_strset_get_policy[ETHTOOL_A_STRSET_COUNTS_O
 extern const struct nla_policy ethnl_linkinfo_get_policy[ETHTOOL_A_LINKINFO_HEADER + 1];
 extern const struct nla_policy ethnl_linkinfo_set_policy[ETHTOOL_A_LINKINFO_TP_MDIX_CTRL + 1];
 extern const struct nla_policy ethnl_linkmodes_get_policy[ETHTOOL_A_LINKMODES_HEADER + 1];
-extern const struct nla_policy ethnl_linkmodes_set_policy[ETHTOOL_A_LINKMODES_MASTER_SLAVE_CFG + 1];
+extern const struct nla_policy ethnl_linkmodes_set_policy[ETHTOOL_A_LINKMODES_LANES + 1];
 extern const struct nla_policy ethnl_linkstate_get_policy[ETHTOOL_A_LINKSTATE_HEADER + 1];
 extern const struct nla_policy ethnl_debug_get_policy[ETHTOOL_A_DEBUG_HEADER + 1];
 extern const struct nla_policy ethnl_debug_set_policy[ETHTOOL_A_DEBUG_MSGMASK + 1];

tools/testing/selftests/drivers/net/mlxsw/ethtool_lanes.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+lib_dir=$(dirname $0)/../../../net/forwarding
+
+ALL_TESTS="
+	autoneg
+	autoneg_force_mode
+"
+
+NUM_NETIFS=2
+: ${TIMEOUT:=30000} # ms
+source $lib_dir/lib.sh
+source $lib_dir/ethtool_lib.sh
+
+setup_prepare()
+{
+	swp1=${NETIFS[p1]}
+	swp2=${NETIFS[p2]}
+
+	ip link set dev $swp1 up
+	ip link set dev $swp2 up
+
+	busywait "$TIMEOUT" wait_for_port_up ethtool $swp2
+	check_err $? "ports did not come up"
+
+	local lanes_exist=$(ethtool $swp1 | grep 'Lanes:')
+	if [[ -z $lanes_exist ]]; then
+		log_test "SKIP: driver does not support lanes setting"
+		exit 1
+	fi
+
+	ip link set dev $swp2 down
+	ip link set dev $swp1 down
+}
+
+check_lanes()
+{
+	local dev=$1; shift
+	local lanes=$1; shift
+	local max_speed=$1; shift
+	local chosen_lanes
+
+	chosen_lanes=$(ethtool $dev | grep 'Lanes:')
+	chosen_lanes=${chosen_lanes#*"Lanes: "}
+
+	((chosen_lanes == lanes))
+	check_err $? "swp1 advertise $max_speed and $lanes, devs sync to $chosen_lanes"
+}
+
+check_unsupported_lanes()
+{
+	local dev=$1; shift
+	local max_speed=$1; shift
+	local max_lanes=$1; shift
+	local autoneg=$1; shift
+	local autoneg_str=""
+
+	local unsupported_lanes=$((max_lanes *= 2))
+
+	if [[ $autoneg -eq 0 ]]; then
+		autoneg_str="autoneg off"
+	fi
+
+	ethtool -s $swp1 speed $max_speed lanes $unsupported_lanes $autoneg_str &> /dev/null
+	check_fail $? "Unsuccessful $unsupported_lanes lanes setting was expected"
+}
+
+max_speed_and_lanes_get()
+{
+	local dev=$1; shift
+	local arr=("$@")
+	local max_lanes
+	local max_speed
+	local -a lanes_arr
+	local -a speeds_arr
+	local -a max_values
+
+	for ((i=0; i<${#arr[@]}; i+=2)); do
+		speeds_arr+=("${arr[$i]}")
+		lanes_arr+=("${arr[i+1]}")
+	done
+
+	max_values+=($(get_max "${speeds_arr[@]}"))
+	max_values+=($(get_max "${lanes_arr[@]}"))
+
+	echo ${max_values[@]}
+}
+
+search_linkmode()
+{
+	local speed=$1; shift
+	local lanes=$1; shift
+	local arr=("$@")
+
+	for ((i=0; i<${#arr[@]}; i+=2)); do
+		if [[ $speed -eq ${arr[$i]} && $lanes -eq ${arr[i+1]} ]]; then
+			return 1
+		fi
+	done
+	return 0
+}
+
+autoneg()
+{
+	RET=0
+
+	local lanes
+	local max_speed
+	local max_lanes
+
+	local -a linkmodes_params=($(dev_linkmodes_params_get $swp1 1))
+	local -a max_values=($(max_speed_and_lanes_get $swp1 "${linkmodes_params[@]}"))
+	max_speed=${max_values[0]}
+	max_lanes=${max_values[1]}
+
+	lanes=$max_lanes
+
+	while [[ $lanes -ge 1 ]]; do
+		search_linkmode $max_speed $lanes "${linkmodes_params[@]}"
+		if [[ $? -eq 1 ]]; then
+			ethtool_set $swp1 speed $max_speed lanes $lanes
+			ip link set dev $swp1 up
+			ip link set dev $swp2 up
+			busywait "$TIMEOUT" wait_for_port_up ethtool $swp2
+			check_err $? "ports did not come up"
+
+			check_lanes $swp1 $lanes $max_speed
+			log_test "$lanes lanes is autonegotiated"
+		fi
+		let $((lanes /= 2))
+	done
+
+	check_unsupported_lanes $swp1 $max_speed $max_lanes 1
+	log_test "Lanes number larger than max width is not set"
+
+	ip link set dev $swp2 down
+	ip link set dev $swp1 down
+}
+
+autoneg_force_mode()
+{
+	RET=0
+
+	local lanes
+	local max_speed
+	local max_lanes
+
+	local -a linkmodes_params=($(dev_linkmodes_params_get $swp1 1))
+	local -a max_values=($(max_speed_and_lanes_get $swp1 "${linkmodes_params[@]}"))
+	max_speed=${max_values[0]}
+	max_lanes=${max_values[1]}
+
+	lanes=$max_lanes
+
+	while [[ $lanes -ge 1 ]]; do
+		search_linkmode $max_speed $lanes "${linkmodes_params[@]}"
+		if [[ $? -eq 1 ]]; then
+			ethtool_set $swp1 speed $max_speed lanes $lanes autoneg off
+			ethtool_set $swp2 speed $max_speed lanes $lanes autoneg off
+			ip link set dev $swp1 up
+			ip link set dev $swp2 up
+			busywait "$TIMEOUT" wait_for_port_up ethtool $swp2
+			check_err $? "ports did not come up"
+
+			check_lanes $swp1 $lanes $max_speed
+			log_test "Autoneg off, $lanes lanes detected during force mode"
+		fi
+		let $((lanes /= 2))
+	done
+
+	check_unsupported_lanes $swp1 $max_speed $max_lanes 0
+	log_test "Lanes number larger than max width is not set"
+
+	ip link set dev $swp2 down
+	ip link set dev $swp1 down
+
+	ethtool -s $swp2 autoneg on
+	ethtool -s $swp1 autoneg on
+}
+
+check_ethtool_lanes_support
+setup_prepare
+
+tests_run
+
+exit $EXIT_STATUS

tools/testing/selftests/net/forwarding/ethtool_lib.sh

@@ -22,6 +22,40 @@ ethtool_set()
 	check_err $out "error in configuration. $cmd"
 }
 
+dev_linkmodes_params_get()
+{
+	local dev=$1; shift
+	local adver=$1; shift
+	local -a linkmodes_params
+	local param_count
+	local arr
+
+	if (($adver)); then
+		mode="Advertised link modes"
+	else
+		mode="Supported link modes"
+	fi
+
+	local -a dev_linkmodes=($(dev_speeds_get $dev 1 $adver))
+	for ((i=0; i<${#dev_linkmodes[@]}; i++)); do
+		linkmodes_params[$i]=$(echo -e "${dev_linkmodes[$i]}" | \
+			# Replaces all non numbers with spaces
+			sed -e 's/[^0-9]/ /g' | \
+			# Squeeze spaces in sequence to 1 space
+			tr -s ' ')
+		# Count how many numbers were found in the linkmode
+		param_count=$(echo "${linkmodes_params[$i]}" | wc -w)
+		if [[ $param_count -eq 1 ]]; then
+			linkmodes_params[$i]="${linkmodes_params[$i]} 1"
+		elif [[ $param_count -ge 3 ]]; then
+			arr=(${linkmodes_params[$i]})
+			# Take only first two params
+			linkmodes_params[$i]=$(echo "${arr[@]:0:2}")
+		fi
+	done
+	echo ${linkmodes_params[@]}
+}
+
 dev_speeds_get()
 {
 	local dev=$1; shift

tools/testing/selftests/net/forwarding/lib.sh

@@ -69,6 +69,15 @@ check_tc_action_hw_stats_support()
 	fi
 }
 
+check_ethtool_lanes_support()
+{
+	ethtool --help 2>&1| grep lanes &> /dev/null
+	if [[ $? -ne 0 ]]; then
+		echo "SKIP: ethtool too old; it is missing lanes support"
+		exit 1
+	fi
+}
+
 if [[ "$(id -u)" -ne 0 ]]; then
 	echo "SKIP: need root privileges"
 	exit 0
@@ -263,6 +272,20 @@ not()
 	[[ $? != 0 ]]
 }
 
+get_max()
+{
+	local arr=("$@")
+
+	max=${arr[0]}
+	for cur in ${arr[@]}; do
+		if [[ $cur -gt $max ]]; then
+			max=$cur
+		fi
+	done
+
+	echo $max
+}
+
 grep_bridge_fdb()
 {
 	local addr=$1; shift
@@ -279,6 +302,11 @@ grep_bridge_fdb()
 	$@ | grep $addr | grep $flag "$word"
 }
 
+wait_for_port_up()
+{
+	"$@" | grep -q "Link detected: yes"
+}
+
 wait_for_offload()
 {
 	"$@" | grep -q offload