From: Vladimir Oltean <vladimir.olt...@nxp.com>

With this patch we try to kill 2 birds with 1 stone.

First of all, some switches that use tag_ocelot.c don't have the exact
same bitfield layout for the DSA tags. The destination ports field is
different for Seville VSC9953 for example. So the choices are to either
duplicate tag_ocelot.c into a new tag_seville.c (sub-optimal) or somehow
take into account a supposed ocelot->dest_ports_offset when packing this
field into the DSA injection header (again not ideal).

Secondly, tag_ocelot.c already needs to memset a 128-bit area to zero
and call some packing() functions of dubious performance in the
fastpath. And most of the values it needs to pack are pretty much
constant (BYPASS=1, SRC_PORT=CPU, DEST=port index). So it would be good
if we could improve that.

The proposed solution is to allocate a memory area per port at probe
time, initialize that with the statically defined bits as per chip
hardware revision, and just perform a simpler memcpy in the fastpath.

Signed-off-by: Vladimir Oltean <vladimir.olt...@nxp.com>
---
 drivers/net/dsa/ocelot/felix.c | 23 +++++++++++++++++++++++
 include/soc/mscc/ocelot.h      |  2 ++
 net/dsa/tag_ocelot.c           | 21 ++++++++-------------
 3 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c
index 8b15cbcb597c..0a392e0f4fbb 100644
--- a/drivers/net/dsa/ocelot/felix.c
+++ b/drivers/net/dsa/ocelot/felix.c
@@ -480,6 +480,8 @@ static int felix_init_structs(struct felix *felix, int 
num_phys_ports)
        for (port = 0; port < num_phys_ports; port++) {
                struct ocelot_port *ocelot_port;
                struct regmap *target;
+               u64 bypass, dest, src;
+               u8 *template;
 
                ocelot_port = devm_kzalloc(ocelot->dev,
                                           sizeof(struct ocelot_port),
@@ -505,9 +507,30 @@ static int felix_init_structs(struct felix *felix, int 
num_phys_ports)
                        return PTR_ERR(target);
                }
 
+               template = devm_kzalloc(ocelot->dev, OCELOT_TAG_LEN,
+                                       GFP_KERNEL);
+               if (!template) {
+                       dev_err(ocelot->dev,
+                               "Failed to allocate memory for DSA tag\n");
+                       kfree(port_phy_modes);
+                       return -ENOMEM;
+               }
+
+               /* Set the source port as the CPU port module and not the
+                * NPI port
+                */
+               src = ocelot->num_phys_ports;
+               dest = BIT(port);
+               bypass = true;
+
+               packing(template, &bypass, 127, 127, OCELOT_TAG_LEN, PACK, 0);
+               packing(template, &dest,    68,  56, OCELOT_TAG_LEN, PACK, 0);
+               packing(template, &src,     46,  43, OCELOT_TAG_LEN, PACK, 0);
+
                ocelot_port->phy_mode = port_phy_modes[port];
                ocelot_port->ocelot = ocelot;
                ocelot_port->target = target;
+               ocelot_port->xmit_template = template;
                ocelot->ports[port] = ocelot_port;
        }
 
diff --git a/include/soc/mscc/ocelot.h b/include/soc/mscc/ocelot.h
index 8e6c13d99ced..1a87a3a32616 100644
--- a/include/soc/mscc/ocelot.h
+++ b/include/soc/mscc/ocelot.h
@@ -549,6 +549,8 @@ struct ocelot_port {
        u8                              ts_id;
 
        phy_interface_t                 phy_mode;
+
+       u8                              *xmit_template;
 };
 
 struct ocelot {
diff --git a/net/dsa/tag_ocelot.c b/net/dsa/tag_ocelot.c
index b0c98ee4e13b..42f327c06dca 100644
--- a/net/dsa/tag_ocelot.c
+++ b/net/dsa/tag_ocelot.c
@@ -137,11 +137,10 @@ static struct sk_buff *ocelot_xmit(struct sk_buff *skb,
                                   struct net_device *netdev)
 {
        struct dsa_port *dp = dsa_slave_to_port(netdev);
-       u64 bypass, dest, src, qos_class, rew_op;
        struct dsa_switch *ds = dp->ds;
-       int port = dp->index;
        struct ocelot *ocelot = ds->priv;
-       struct ocelot_port *ocelot_port = ocelot->ports[port];
+       struct ocelot_port *ocelot_port;
+       u64 qos_class, rew_op;
        u8 *injection;
 
        if (unlikely(skb_cow_head(skb, OCELOT_TAG_LEN) < 0)) {
@@ -149,19 +148,15 @@ static struct sk_buff *ocelot_xmit(struct sk_buff *skb,
                return NULL;
        }
 
-       injection = skb_push(skb, OCELOT_TAG_LEN);
+       ocelot_port = ocelot->ports[dp->index];
 
-       memset(injection, 0, OCELOT_TAG_LEN);
+       injection = skb_push(skb, OCELOT_TAG_LEN);
 
-       /* Set the source port as the CPU port module and not the NPI port */
-       src = ocelot->num_phys_ports;
-       dest = BIT(port);
-       bypass = true;
+       memcpy(injection, ocelot_port->xmit_template, OCELOT_TAG_LEN);
+       /* Fix up the fields which are not statically determined
+        * in the template
+        */
        qos_class = skb->priority;
-
-       packing(injection, &bypass,   127, 127, OCELOT_TAG_LEN, PACK, 0);
-       packing(injection, &dest,      68,  56, OCELOT_TAG_LEN, PACK, 0);
-       packing(injection, &src,       46,  43, OCELOT_TAG_LEN, PACK, 0);
        packing(injection, &qos_class, 19,  17, OCELOT_TAG_LEN, PACK, 0);
 
        if (ocelot->ptp && (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) {
-- 
2.25.1

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