[PATCH net-next] net: airoha: Fix GDM2 loopback configuration for USB serdes

[Lorenzo Bianconi]

Flow Control source port mapping for USB serdes needs to be configured
according to the GDM port nbd parameter. This is a preliminary patch
since nbd parameter is specific for the given port serdes and needs to
be read from the DTS (in the current codebase is assigned statically).

Signed-off-by: Lorenzo Bianconi <lorenzo at kernel.org>
---
 drivers/net/ethernet/airoha/airoha_eth.c  | 10 ++++++----
 drivers/net/ethernet/airoha/airoha_regs.h |  5 +----
 2 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
index 3779f93b47bc13ae21d4ae088dece4712dc214e5..37fc2b33d3af8a190a74efc69ed54f163afa6412 100644
--- a/drivers/net/ethernet/airoha/airoha_eth.c
+++ b/drivers/net/ethernet/airoha/airoha_eth.c
@@ -1729,10 +1729,12 @@ static int airhoha_set_gdm2_loopback(struct airoha_gdm_port *port)
 		      SP_CPORT_MASK(val),
 		      FE_PSE_PORT_CDM2 << __ffs(SP_CPORT_MASK(val)));
 
-	if (port->id != AIROHA_GDM3_IDX && airoha_is_7581(eth))
-		airoha_fe_rmw(eth, REG_SRC_PORT_FC_MAP6,
-			      FC_ID_OF_SRC_PORT24_MASK,
-			      FIELD_PREP(FC_ID_OF_SRC_PORT24_MASK, 2));
+	if (port->id == AIROHA_GDM4_IDX && airoha_is_7581(eth)) {
+		u32 mask = FC_ID_OF_SRC_PORT_MASK(nbq);
+
+		airoha_fe_rmw(eth, REG_SRC_PORT_FC_MAP6, mask,
+			      AIROHA_GDM2_IDX << __ffs(mask));
+	}
 
 	return 0;
 }
diff --git a/drivers/net/ethernet/airoha/airoha_regs.h b/drivers/net/ethernet/airoha/airoha_regs.h
index ed4e3407f4a0e8b6a630ea1213ef155604479b66..29878b954c77c79ae45e63357840a10c23c517f2 100644
--- a/drivers/net/ethernet/airoha/airoha_regs.h
+++ b/drivers/net/ethernet/airoha/airoha_regs.h
@@ -376,10 +376,7 @@
 #define SP_CPORT_MASK(_n)		GENMASK(3 + ((_n) << 2), ((_n) << 2))
 
 #define REG_SRC_PORT_FC_MAP6		0x2298
-#define FC_ID_OF_SRC_PORT27_MASK	GENMASK(28, 24)
-#define FC_ID_OF_SRC_PORT26_MASK	GENMASK(20, 16)
-#define FC_ID_OF_SRC_PORT25_MASK	GENMASK(12, 8)
-#define FC_ID_OF_SRC_PORT24_MASK	GENMASK(4, 0)
+#define FC_ID_OF_SRC_PORT_MASK(_n)	GENMASK(4 + ((_n) << 3), ((_n) << 3))
 
 #define REG_CDM5_RX_OQ1_DROP_CNT	0x29d4
 

---
base-commit: 621e3634dfab890e8d97e082588b3d6d6d688d91
change-id: 20260228-airoha-fix-loopback-for-usb-serdes-2670a0146195

Best regards,
-- 
Lorenzo Bianconi <lorenzo at kernel.org>