From d405dd77765b3573ba2aea3d59e688d2fc0be3ee Mon Sep 17 00:00:00 2001
From: d00f <8052722+DrDoof@users.noreply.github.com>
Date: Sun, 16 Aug 2026 01:52:03 +0200
Subject: [PATCH] port: let a pvid name an aggregation group

VLAN membership, PVID, egress tagging, isolation and MTU are all per
physical port in this ASIC, so nothing stopped a member of a working
aggregation group being given a different PVID from its peers. The group
then forwards asymmetrically depending on which member the hash picks,
and no part of the firmware says a word about it.

port_lag_of() answers which group a port belongs to, reading the
membership through the shared reader rather than a fourth private copy.
port_pvid_set() expands to the whole group when the port it is given is
a member, and ports outside a group keep the path they had.

This is the second and third of the three steps set out in #347. I said
there that the lookup would come when something needed it, which had it
the wrong way round: nothing in the tree asks which group a port is in,
so the lookup only earns its place alongside a caller. PVID is the
smallest such caller, and the rest of the per port settings can follow
the same shape once this one is agreed.

Built for SWTGW218AS and KP_9000_6XHML_X2 on sdcc 4.5.0.
---
 rtl837x_port.c | 27 +++++++++++++++++++++++++--
 rtl837x_port.h |  2 ++
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/rtl837x_port.c b/rtl837x_port.c
index 9388cc6..0a7cabf 100644
--- a/rtl837x_port.c
+++ b/rtl837x_port.c
@@ -87,10 +87,9 @@ vlan_ingress_mode_t port_ingress_filter_get(__xdata uint8_t port) __banked
 /*
  * Define a Primary VLAN ID for a port 
 */
-void port_pvid_set(uint8_t port, __xdata uint16_t pvid) __banked
+static void port_pvid_write(uint8_t port, __xdata uint16_t pvid)
 {
 	// r4e1c:00001001 R4e1c-000017d0 r6738:00000000 R6738-00000000 (no filtering)
-	print_string("\nport_pvid_set called \n");
 	uint16_t reg = RTL837x_PVID_BASE_REG + ((port >> 1) << 2);
 
 	reg_read_m(reg);
@@ -101,6 +100,22 @@ void port_pvid_set(uint8_t port, __xdata uint16_t pvid) __banked
 	}
 }
 
+void port_pvid_set(uint8_t port, __xdata uint16_t pvid) __banked
+{
+	uint8_t lag = port_lag_of(port);
+
+	print_string("\nport_pvid_set called \n");
+	if (lag == PORT_LAG_NONE) {
+		port_pvid_write(port, pvid);
+		return;
+	}
+
+	uint16_t members = port_lag_members_get(lag);
+	for (uint8_t i = 0; i < 10; i++)
+		if ((members >> i) & 1)
+			port_pvid_write(i, pvid);
+}
+
 uint16_t port_pvid_get(uint8_t port) __banked
 {
 	uint16_t reg = RTL837x_PVID_BASE_REG + ((port >> 1) << 2);
@@ -745,6 +760,14 @@ uint16_t port_lag_members_get(uint8_t lag) __banked
 	return ((uint16_t)SFR_DATA_8 << 8) | SFR_DATA_0;
 }
 
+uint8_t port_lag_of(uint8_t port) __banked
+{
+	for (uint8_t lag = 0; lag < 4; lag++)
+		if ((port_lag_members_get(lag) >> port) & 1)
+			return lag;
+	return PORT_LAG_NONE;
+}
+
 
 /*
  * Configure LAGs
diff --git a/rtl837x_port.h b/rtl837x_port.h
index b459832..c0185a1 100644
--- a/rtl837x_port.h
+++ b/rtl837x_port.h
@@ -62,6 +62,8 @@ void port_mirror_del(void) __banked;
 bool port_ingress_filter(__xdata uint8_t port, __xdata vlan_ingress_mode_t type) __banked;
 void port_l2_setup(void) __banked;
 uint16_t port_lag_members_get(uint8_t lag) __banked;
+#define PORT_LAG_NONE 0xff
+uint8_t port_lag_of(uint8_t port) __banked;
 void port_lag_members_set(__xdata uint8_t lag, __xdata uint16_t members) __banked;
 void port_lag_hash_set(__xdata uint8_t lag, __xdata uint8_t hash) __banked;
 void port_eee_enable_all(__xdata uint8_t speed) __banked;