[openwrt/openwrt] airoha: backport patch fixing offload support with GDM2 present

[LEDE Commits]

ansuel pushed a commit to openwrt/openwrt.git, branch main:
https://git.openwrt.org/b7aa0aa9bf603c01500f791df4636b35434c6224

commit b7aa0aa9bf603c01500f791df4636b35434c6224
Author: Christian Marangi <ansuelsmth at gmail.com>
AuthorDate: Tue Nov 18 12:50:50 2025 +0100

    airoha: backport patch fixing offload support with GDM2 present
    
    Backport upstream patch fixing offload support in the presence of GDM2
    interface.
    
    Signed-off-by: Christian Marangi <ansuelsmth at gmail.com>
---
 ...Do-not-loopback-traffic-to-GDM2-if-it-is-.patch | 31 ++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/target/linux/airoha/patches-6.12/110-v6.19-net-airoha-Do-not-loopback-traffic-to-GDM2-if-it-is-.patch b/target/linux/airoha/patches-6.12/110-v6.19-net-airoha-Do-not-loopback-traffic-to-GDM2-if-it-is-.patch
new file mode 100644
index 0000000000..526243eed2
--- /dev/null
+++ b/target/linux/airoha/patches-6.12/110-v6.19-net-airoha-Do-not-loopback-traffic-to-GDM2-if-it-is-.patch
@@ -0,0 +1,31 @@
+From 8e0a754b0836d996802713bbebc87bc1cc17925c Mon Sep 17 00:00:00 2001
+From: Lorenzo Bianconi <lorenzo at kernel.org>
+Date: Thu, 13 Nov 2025 18:19:38 +0100
+Subject: [PATCH] net: airoha: Do not loopback traffic to GDM2 if it is
+ available on the device
+
+Airoha_eth driver forwards offloaded uplink traffic (packets received
+on GDM1 and forwarded to GDM{3,4}) to GDM2 in order to apply hw QoS.
+This is correct if the device does not support a dedicated GDM2 port.
+In this case, in order to enable hw offloading for uplink traffic,
+the packets should be sent to GDM{3,4} directly.
+
+Fixes: 9cd451d414f6 ("net: airoha: Add loopback support for GDM2")
+Signed-off-by: Lorenzo Bianconi <lorenzo at kernel.org>
+Link: https://patch.msgid.link/20251113-airoha-hw-offload-gdm2-fix-v1-1-7e4ca300872f@kernel.org
+Signed-off-by: Jakub Kicinski <kuba at kernel.org>
+---
+ drivers/net/ethernet/airoha/airoha_ppe.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/net/ethernet/airoha/airoha_ppe.c
++++ b/drivers/net/ethernet/airoha/airoha_ppe.c
+@@ -308,7 +308,7 @@ static int airoha_ppe_foe_entry_prepare(
+ 			if (!airoha_is_valid_gdm_port(eth, port))
+ 				return -EINVAL;
+ 
+-			if (dsa_port >= 0)
++			if (dsa_port >= 0 || eth->ports[1])
+ 				pse_port = port->id == 4 ? FE_PSE_PORT_GDM4
+ 							 : port->id;
+ 			else