netdev - [RESEND PATCH net-next v2] amd-xgbe: add support for giant packet size

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Message-ID: <20250701121929.319690-1-Raju.Rangoju@amd.com>
Date: Tue, 1 Jul 2025 17:49:29 +0530
From: Raju Rangoju <Raju.Rangoju@....com>
To: <andrew+netdev@...n.ch>, <davem@...emloft.net>, <edumazet@...gle.com>,
	<kuba@...nel.org>, <pabeni@...hat.com>
CC: <netdev@...r.kernel.org>, <Shyam-sundar.S-k@....com>, Raju Rangoju
	<Raju.Rangoju@....com>
Subject: [RESEND PATCH net-next v2] amd-xgbe: add support for giant packet size

AMD XGBE hardware supports giant Ethernet frames up to 16K bytes.
Add support for configuring and enabling giant packet handling
in the driver.

- Define new register fields and macros for giant packet support.
- Update the jumbo frame configuration logic to enable giant
  packet mode when MTU exceeds the jumbo threshold.

Acked-by: Shyam Sundar S K <Shyam-sundar.S-k@....com>
Signed-off-by: Raju Rangoju <Raju.Rangoju@....com>
---
 drivers/net/ethernet/amd/xgbe/xgbe-common.h |  8 ++++++++
 drivers/net/ethernet/amd/xgbe/xgbe-dev.c    | 16 +++++++++++++---
 drivers/net/ethernet/amd/xgbe/xgbe-main.c   |  2 +-
 drivers/net/ethernet/amd/xgbe/xgbe.h        |  2 ++
 4 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-common.h b/drivers/net/ethernet/amd/xgbe/xgbe-common.h
index e1296cbf4ff3..734f44660620 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-common.h
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-common.h
@@ -364,6 +364,10 @@
 #define MAC_RCR_CST_WIDTH		1
 #define MAC_RCR_DCRCC_INDEX		3
 #define MAC_RCR_DCRCC_WIDTH		1
+#define MAC_RCR_GPSLCE_INDEX		6
+#define MAC_RCR_GPSLCE_WIDTH		1
+#define MAC_RCR_WD_INDEX		7
+#define MAC_RCR_WD_WIDTH		1
 #define MAC_RCR_HDSMS_INDEX		12
 #define MAC_RCR_HDSMS_WIDTH		3
 #define MAC_RCR_IPC_INDEX		9
@@ -374,6 +378,8 @@
 #define MAC_RCR_LM_WIDTH		1
 #define MAC_RCR_RE_INDEX		0
 #define MAC_RCR_RE_WIDTH		1
+#define MAC_RCR_GPSL_INDEX		16
+#define MAC_RCR_GPSL_WIDTH		14
 #define MAC_RFCR_PFCE_INDEX		8
 #define MAC_RFCR_PFCE_WIDTH		1
 #define MAC_RFCR_RFE_INDEX		0
@@ -412,6 +418,8 @@
 #define MAC_TCR_VNE_WIDTH		1
 #define MAC_TCR_VNM_INDEX		25
 #define MAC_TCR_VNM_WIDTH		1
+#define MAC_TCR_JD_INDEX		16
+#define MAC_TCR_JD_WIDTH		1
 #define MAC_TIR_TNID_INDEX		0
 #define MAC_TIR_TNID_WIDTH		16
 #define MAC_TSCR_AV8021ASMEN_INDEX	28
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
index 466b5f6e5578..9e4e79bfe624 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
@@ -2850,9 +2850,19 @@ static void xgbe_config_jumbo_enable(struct xgbe_prv_data *pdata)
 {
 	unsigned int val;
 
-	val = (pdata->netdev->mtu > XGMAC_STD_PACKET_MTU) ? 1 : 0;
-
-	XGMAC_IOWRITE_BITS(pdata, MAC_RCR, JE, val);
+	if (pdata->netdev->mtu > XGMAC_JUMBO_PACKET_MTU) {
+		XGMAC_IOWRITE_BITS(pdata, MAC_RCR, GPSL,
+				   XGMAC_GIANT_PACKET_MTU);
+		XGMAC_IOWRITE_BITS(pdata, MAC_RCR, WD, 1);
+		XGMAC_IOWRITE_BITS(pdata, MAC_TCR, JD, 1);
+		XGMAC_IOWRITE_BITS(pdata, MAC_RCR, GPSLCE, 1);
+	} else {
+		val = pdata->netdev->mtu > XGMAC_STD_PACKET_MTU ? 1 : 0;
+		XGMAC_IOWRITE_BITS(pdata, MAC_RCR, GPSLCE, 0);
+		XGMAC_IOWRITE_BITS(pdata, MAC_RCR, WD, 0);
+		XGMAC_IOWRITE_BITS(pdata, MAC_TCR, JD, 0);
+		XGMAC_IOWRITE_BITS(pdata, MAC_RCR, JE, val);
+	}
 }
 
 static void xgbe_config_mac_speed(struct xgbe_prv_data *pdata)
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-main.c b/drivers/net/ethernet/amd/xgbe/xgbe-main.c
index 4ebdd123c435..d1f0419edb23 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-main.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-main.c
@@ -275,7 +275,7 @@ int xgbe_config_netdev(struct xgbe_prv_data *pdata)
 
 	netdev->priv_flags |= IFF_UNICAST_FLT;
 	netdev->min_mtu = 0;
-	netdev->max_mtu = XGMAC_JUMBO_PACKET_MTU;
+	netdev->max_mtu = XGMAC_GIANT_PACKET_MTU - XGBE_ETH_FRAME_HDR;
 
 	/* Use default watchdog timeout */
 	netdev->watchdog_timeo = 0;
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe.h b/drivers/net/ethernet/amd/xgbe/xgbe.h
index 3e90631d0a4f..5d64cd9a028b 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe.h
+++ b/drivers/net/ethernet/amd/xgbe/xgbe.h
@@ -80,11 +80,13 @@
 #define XGBE_IRQ_MODE_EDGE	0
 #define XGBE_IRQ_MODE_LEVEL	1
 
+#define XGBE_ETH_FRAME_HDR	(ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN)
 #define XGMAC_MIN_PACKET	60
 #define XGMAC_STD_PACKET_MTU	1500
 #define XGMAC_MAX_STD_PACKET	1518
 #define XGMAC_JUMBO_PACKET_MTU	9000
 #define XGMAC_MAX_JUMBO_PACKET	9018
+#define XGMAC_GIANT_PACKET_MTU	16368
 #define XGMAC_ETH_PREAMBLE	(12 + 8)	/* Inter-frame gap + preamble */
 
 #define XGMAC_PFC_DATA_LEN	46
-- 
2.34.1