net: dsa: tag_yt921x: clarify priority and code fields

Packet priority is part of the tag, and the priority and code fields are
used by tx and rx. Make revisions to reflect the facts.

Signed-off-by: David Yang <mmyangfl@gmail.com>
Link: https://patch.msgid.link/20260131021854.3405036-2-mmyangfl@gmail.com
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/dsa/tag_yt921x.c b/net/dsa/tag_yt921x.c
index 6bbfd42dc5dfe2356f3084fe39e0fc6039146681..098863d491ff7ec6de59c7ea2d7e80c5b74f25b8 100644 (file)
--- a/net/dsa/tag_yt921x.c
+++ b/net/dsa/tag_yt921x.c
@@ -14,11 +14,14 @@
  *     are conflicts somewhere and/or you want to change it for some reason.
  * Tag:
  *   2: VLAN Tag
- *   2: Rx Port
+ *   2:
  *     15b: Rx Port Valid
  *     14b-11b: Rx Port
- *     10b-0b: Cmd?
- *   2: Tx Port(s)
+ *     10b-8b: Tx/Rx Priority
+ *     7b: Tx/Rx Code Valid
+ *     6b-1b: Tx/Rx Code
+ *     0b: ? (unset)
+ *   2:
  *     15b: Tx Port(s) Valid
  *     10b-0b: Tx Port(s) Mask
  */
@@ -33,18 +36,30 @@
 
 #define YT921X_TAG_PORT_EN             BIT(15)
 #define YT921X_TAG_RX_PORT_M           GENMASK(14, 11)
-#define YT921X_TAG_RX_CMD_M            GENMASK(10, 0)
-#define  YT921X_TAG_RX_CMD(x)                  FIELD_PREP(YT921X_TAG_RX_CMD_M, (x))
-#define  YT921X_TAG_RX_CMD_FORWARDED           0x80
-#define  YT921X_TAG_RX_CMD_UNK_UCAST           0xb2
-#define  YT921X_TAG_RX_CMD_UNK_MCAST           0xb4
-#define YT921X_TAG_TX_PORTS            GENMASK(10, 0)
+#define YT921X_TAG_PRIO_M              GENMASK(10, 8)
+#define  YT921X_TAG_PRIO(x)                    FIELD_PREP(YT921X_TAG_PRIO_M, (x))
+#define YT921X_TAG_CODE_EN             BIT(7)
+#define YT921X_TAG_CODE_M              GENMASK(6, 1)
+#define  YT921X_TAG_CODE(x)                    FIELD_PREP(YT921X_TAG_CODE_M, (x))
+#define YT921X_TAG_TX_PORTS_M          GENMASK(10, 0)
+#define  YT921X_TAG_TX_PORTS(x)                        FIELD_PREP(YT921X_TAG_TX_PORTS_M, (x))
+
+/* Incomplete. Some are configurable via RMA_CTRL_CPU_CODE, the meaning of
+ * others remains unknown.
+ */
+enum yt921x_tag_code {
+       YT921X_TAG_CODE_FORWARD = 0,
+       YT921X_TAG_CODE_UNK_UCAST = 0x19,
+       YT921X_TAG_CODE_UNK_MCAST = 0x1a,
+       YT921X_TAG_CODE_PORT_COPY = 0x1b,
+       YT921X_TAG_CODE_FDB_COPY = 0x1c,
+};
 
 static struct sk_buff *
 yt921x_tag_xmit(struct sk_buff *skb, struct net_device *netdev)
 {
        __be16 *tag;
-       u16 tx;
+       u16 ctrl;
 
        skb_push(skb, YT921X_TAG_LEN);
        dsa_alloc_etype_header(skb, YT921X_TAG_LEN);
@@ -55,9 +70,9 @@ yt921x_tag_xmit(struct sk_buff *skb, struct net_device *netdev)
        /* VLAN tag unrelated when TX */
        tag[1] = 0;
        tag[2] = 0;
-       tx = FIELD_PREP(YT921X_TAG_TX_PORTS, dsa_xmit_port_mask(skb, netdev)) |
-            YT921X_TAG_PORT_EN;
-       tag[3] = htons(tx);
+       ctrl = YT921X_TAG_TX_PORTS(dsa_xmit_port_mask(skb, netdev)) |
+              YT921X_TAG_PORT_EN;
+       tag[3] = htons(ctrl);
 
        return skb;
 }
@@ -67,7 +82,6 @@ yt921x_tag_rcv(struct sk_buff *skb, struct net_device *netdev)
 {
        unsigned int port;
        __be16 *tag;
-       u16 cmd;
        u16 rx;
 
        if (unlikely(!pskb_may_pull(skb, YT921X_TAG_LEN)))
@@ -98,23 +112,32 @@ yt921x_tag_rcv(struct sk_buff *skb, struct net_device *netdev)
                return NULL;
        }
 
-       cmd = FIELD_GET(YT921X_TAG_RX_CMD_M, rx);
-       switch (cmd) {
-       case YT921X_TAG_RX_CMD_FORWARDED:
-               /* Already forwarded by hardware */
-               dsa_default_offload_fwd_mark(skb);
-               break;
-       case YT921X_TAG_RX_CMD_UNK_UCAST:
-       case YT921X_TAG_RX_CMD_UNK_MCAST:
-               /* NOTE: hardware doesn't distinguish between TRAP (copy to CPU
-                * only) and COPY (forward and copy to CPU). In order to perform
-                * a soft switch, NEVER use COPY action in the switch driver.
-                */
-               break;
-       default:
+       if (!(rx & YT921X_TAG_CODE_EN)) {
                dev_warn_ratelimited(&netdev->dev,
-                                    "Unexpected rx cmd 0x%02x\n", cmd);
-               break;
+                                    "Tag code not enabled in rx packet\n");
+       } else {
+               u16 code = FIELD_GET(YT921X_TAG_CODE_M, rx);
+
+               switch (code) {
+               case YT921X_TAG_CODE_FORWARD:
+               case YT921X_TAG_CODE_PORT_COPY:
+               case YT921X_TAG_CODE_FDB_COPY:
+                       /* Already forwarded by hardware */
+                       dsa_default_offload_fwd_mark(skb);
+                       break;
+               case YT921X_TAG_CODE_UNK_UCAST:
+               case YT921X_TAG_CODE_UNK_MCAST:
+                       /* NOTE: hardware doesn't distinguish between TRAP (copy
+                        * to CPU only) and COPY (forward and copy to CPU). In
+                        * order to perform a soft switch, NEVER use COPY action
+                        * in the switch driver.
+                        */
+                       break;
+               default:
+                       dev_warn_ratelimited(&netdev->dev,
+                                            "Unknown code 0x%02x\n", code);
+                       break;
+               }
        }
 
        /* Remove YT921x tag and update checksum */