net: mscc: ocelot: add support for preemptible traffic classes

In order to not transmit (preemptible) frames which will be received by
the link partner as corrupted (because it doesn't support FP), the
hardware requires the driver to program the QSYS_PREEMPTION_CFG_P_QUEUES
register only after the MAC Merge layer becomes active (verification
succeeds, or was disabled).

There are some cases when FP is known (through experimentation) to be
broken. Give priority to FP over cut-through switching, and disable FP
for known broken link modes.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c
index e055b3980ccc5fedd1bca89bf0850ffe6c99ea07..cfb3faeaa5bfa9ee282fe28e3084bf8dbc5d1e5c 100644 (file)
--- a/drivers/net/dsa/ocelot/felix_vsc9959.c
+++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
@@ -2519,6 +2519,7 @@ static void vsc9959_cut_through_fwd(struct ocelot *ocelot)
 
        for (port = 0; port < ocelot->num_phys_ports; port++) {
                struct ocelot_port *ocelot_port = ocelot->ports[port];
+               struct ocelot_mm_state *mm = &ocelot->mm[port];
                int min_speed = ocelot_port->speed;
                unsigned long mask = 0;
                u32 tmp, val = 0;
@@ -2559,10 +2560,12 @@ static void vsc9959_cut_through_fwd(struct ocelot *ocelot)
 
                /* Enable cut-through forwarding for all traffic classes that
                 * don't have oversized dropping enabled, since this check is
-                * bypassed in cut-through mode.
+                * bypassed in cut-through mode. Also exclude preemptible
+                * traffic classes, since these would hang the port for some
+                * reason, if sent as cut-through.
                 */
                if (ocelot_port->speed == min_speed) {
-                       val = GENMASK(7, 0);
+                       val = GENMASK(7, 0) & ~mm->active_preemptible_tcs;
 
                        for (tc = 0; tc < OCELOT_NUM_TC; tc++)
                                if (vsc9959_port_qmaxsdu_get(ocelot, port, tc))

diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
index 8dc5fb1bc61b804763e85de82b04614e85e24138..1f5f00b3044180ff036082e073a7854c6e412492 100644 (file)
--- a/drivers/net/ethernet/mscc/ocelot.c
+++ b/drivers/net/ethernet/mscc/ocelot.c
@@ -1006,7 +1006,12 @@ void ocelot_phylink_mac_link_up(struct ocelot *ocelot, int port,
         */
        if (ocelot->ops->cut_through_fwd) {
                mutex_lock(&ocelot->fwd_domain_lock);
-               ocelot->ops->cut_through_fwd(ocelot);
+               /* Workaround for hardware bug - FP doesn't work
+                * at all link speeds for all PHY modes. The function
+                * below also calls ocelot->ops->cut_through_fwd(),
+                * so we don't need to do it twice.
+                */
+               ocelot_port_update_active_preemptible_tcs(ocelot, port);
                mutex_unlock(&ocelot->fwd_domain_lock);
        }
 
@@ -2705,6 +2710,7 @@ static void ocelot_port_reset_mqprio(struct ocelot *ocelot, int port)
        struct net_device *dev = ocelot->ops->port_to_netdev(ocelot, port);
 
        netdev_reset_tc(dev);
+       ocelot_port_change_fp(ocelot, port, 0);
 }
 
 int ocelot_port_mqprio(struct ocelot *ocelot, int port,
@@ -2741,6 +2747,8 @@ int ocelot_port_mqprio(struct ocelot *ocelot, int port,
        if (err)
                goto err_reset_tc;
 
+       ocelot_port_change_fp(ocelot, port, mqprio->preemptible_tcs);
+
        return 0;
 
 err_reset_tc:

diff --git a/drivers/net/ethernet/mscc/ocelot.h b/drivers/net/ethernet/mscc/ocelot.h
index d920ca930690abecef502d39723ce00bbb182ff3..14440a3b04c3c09d1ee5bfe950cf5ebf67bea9b9 100644 (file)
--- a/drivers/net/ethernet/mscc/ocelot.h
+++ b/drivers/net/ethernet/mscc/ocelot.h
@@ -119,6 +119,9 @@ int ocelot_stats_init(struct ocelot *ocelot);
 void ocelot_stats_deinit(struct ocelot *ocelot);
 
 int ocelot_mm_init(struct ocelot *ocelot);
+void ocelot_port_change_fp(struct ocelot *ocelot, int port,
+                          unsigned long preemptible_tcs);
+void ocelot_port_update_active_preemptible_tcs(struct ocelot *ocelot, int port);
 
 extern struct notifier_block ocelot_netdevice_nb;
 extern struct notifier_block ocelot_switchdev_nb;

diff --git a/drivers/net/ethernet/mscc/ocelot_mm.c b/drivers/net/ethernet/mscc/ocelot_mm.c
index 3e458f72f645ed3d2c2ca3830daf0dbf7a191241..fb3145118d686fd7c3fa77748a34566a987601a5 100644 (file)
--- a/drivers/net/ethernet/mscc/ocelot_mm.c
+++ b/drivers/net/ethernet/mscc/ocelot_mm.c
@@ -49,6 +49,59 @@ static enum ethtool_mm_verify_status ocelot_mm_verify_status(u32 val)
        }
 }
 
+void ocelot_port_update_active_preemptible_tcs(struct ocelot *ocelot, int port)
+{
+       struct ocelot_port *ocelot_port = ocelot->ports[port];
+       struct ocelot_mm_state *mm = &ocelot->mm[port];
+       u32 val = 0;
+
+       lockdep_assert_held(&ocelot->fwd_domain_lock);
+
+       /* Only commit preemptible TCs when MAC Merge is active.
+        * On NXP LS1028A, when using QSGMII, the port hangs if transmitting
+        * preemptible frames at any other link speed than gigabit, so avoid
+        * preemption at lower speeds in this PHY mode.
+        */
+       if ((ocelot_port->phy_mode != PHY_INTERFACE_MODE_QSGMII ||
+            ocelot_port->speed == SPEED_1000) && mm->tx_active)
+               val = mm->preemptible_tcs;
+
+       /* Cut through switching doesn't work for preemptible priorities,
+        * so first make sure it is disabled.
+        */
+       mm->active_preemptible_tcs = val;
+       ocelot->ops->cut_through_fwd(ocelot);
+
+       dev_dbg(ocelot->dev,
+               "port %d %s/%s, MM TX %s, preemptible TCs 0x%x, active 0x%x\n",
+               port, phy_modes(ocelot_port->phy_mode),
+               phy_speed_to_str(ocelot_port->speed),
+               mm->tx_active ? "active" : "inactive", mm->preemptible_tcs,
+               mm->active_preemptible_tcs);
+
+       ocelot_rmw_rix(ocelot, QSYS_PREEMPTION_CFG_P_QUEUES(val),
+                      QSYS_PREEMPTION_CFG_P_QUEUES_M,
+                      QSYS_PREEMPTION_CFG, port);
+}
+
+void ocelot_port_change_fp(struct ocelot *ocelot, int port,
+                          unsigned long preemptible_tcs)
+{
+       struct ocelot_mm_state *mm = &ocelot->mm[port];
+
+       mutex_lock(&ocelot->fwd_domain_lock);
+
+       if (mm->preemptible_tcs == preemptible_tcs)
+               goto out_unlock;
+
+       mm->preemptible_tcs = preemptible_tcs;
+
+       ocelot_port_update_active_preemptible_tcs(ocelot, port);
+
+out_unlock:
+       mutex_unlock(&ocelot->fwd_domain_lock);
+}
+
 static void ocelot_mm_update_port_status(struct ocelot *ocelot, int port)
 {
        struct ocelot_port *ocelot_port = ocelot->ports[port];
@@ -74,6 +127,7 @@ static void ocelot_mm_update_port_status(struct ocelot *ocelot, int port)
 
                dev_dbg(ocelot->dev, "Port %d TX preemption %s\n",
                        port, mm->tx_active ? "active" : "inactive");
+               ocelot_port_update_active_preemptible_tcs(ocelot, port);
 
                ack |= DEV_MM_STAT_MM_STATUS_PRMPT_ACTIVE_STICKY;
        }

diff --git a/include/soc/mscc/ocelot.h b/include/soc/mscc/ocelot.h
index 9596c79e92239c7f8645580d9430fd703bdb499d..cb8fbb2418795a8043a7db25f099835f0439257d 100644 (file)
--- a/include/soc/mscc/ocelot.h
+++ b/include/soc/mscc/ocelot.h
@@ -749,6 +749,8 @@ struct ocelot_mm_state {
        enum ethtool_mm_verify_status verify_status;
        bool tx_enabled;
        bool tx_active;
+       u8 preemptible_tcs;
+       u8 active_preemptible_tcs;
 };
 
 struct ocelot_port;
@@ -1158,6 +1160,7 @@ int ocelot_port_get_mm(struct ocelot *ocelot, int port,
                       struct ethtool_mm_state *state);
 int ocelot_port_mqprio(struct ocelot *ocelot, int port,
                       struct tc_mqprio_qopt_offload *mqprio);
+void ocelot_port_update_preemptible_tcs(struct ocelot *ocelot, int port);
 
 #if IS_ENABLED(CONFIG_BRIDGE_MRP)
 int ocelot_mrp_add(struct ocelot *ocelot, int port,