Subject: [PATCH v3 net-next 2/8] bgmac: configure MTU and add support for frames beyond 8192 byte size

From: Vladimir Oltean <[email-masked]>
Date: Fri, 27 Mar 2020 00:40:34 +0200

From: Murali Krishna Policharla <[email-masked]>

Change DMA descriptor length to handle jumbo frames beyond 8192 bytes.
Also update jumbo frame max size to include FCS, the DMA packet length
received includes FCS.

Signed-off-by: Murali Krishna Policharla <[email-masked]>
Reviewed-by: Arun Parameswaran <[email-masked]>
Reviewed-by: Ray Jui <[email-masked]>
Signed-off-by: Vladimir Oltean <[email-masked]>
---
Changes in v3:
Squashed the entire bgmac implementation in one patch.

Changes in v2:
Patch is new.

 drivers/net/ethernet/broadcom/bgmac.c | 12 ++++++++++++
 drivers/net/ethernet/broadcom/bgmac.h |  5 +++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bgmac.c b/drivers/net/ethernet/broadcom/bgmac.c
index 1bb07a5d82c9..98ec1b8a7d8e 100644
--- a/drivers/net/ethernet/broadcom/bgmac.c
+++ b/drivers/net/ethernet/broadcom/bgmac.c
@@ -1248,6 +1248,14 @@ static int bgmac_set_mac_address(struct net_device *net_dev, void *addr)
 	return 0;
 }
 
+static int bgmac_change_mtu(struct net_device *net_dev, int mtu)
+{
+	struct bgmac *bgmac = netdev_priv(net_dev);
+
+	bgmac_write(bgmac, BGMAC_RXMAX_LENGTH, 32 + mtu);
+	return 0;
+}
+
 static const struct net_device_ops bgmac_netdev_ops = {
 	.ndo_open		= bgmac_open,
 	.ndo_stop		= bgmac_stop,
@@ -1256,6 +1264,7 @@ static const struct net_device_ops bgmac_netdev_ops = {
 	.ndo_set_mac_address	= bgmac_set_mac_address,
 	.ndo_validate_addr	= eth_validate_addr,
 	.ndo_do_ioctl           = phy_do_ioctl_running,
+	.ndo_change_mtu		= bgmac_change_mtu,
 };
 
 /**************************************************
@@ -1530,6 +1539,9 @@ int bgmac_enet_probe(struct bgmac *bgmac)
 	net_dev->hw_features = net_dev->features;
 	net_dev->vlan_features = net_dev->features;
 
+	/* Omit FCS from max MTU size */
+	net_dev->max_mtu = BGMAC_RX_MAX_FRAME_SIZE - ETH_FCS_LEN;
+
 	err = register_netdev(bgmac->net_dev);
 	if (err) {
 		dev_err(bgmac->dev, "Cannot register net device\n");
diff --git a/drivers/net/ethernet/broadcom/bgmac.h b/drivers/net/ethernet/broadcom/bgmac.h
index 40d02fec2747..351c598a3ec6 100644
--- a/drivers/net/ethernet/broadcom/bgmac.h
+++ b/drivers/net/ethernet/broadcom/bgmac.h
@@ -351,7 +351,7 @@
 #define BGMAC_DESC_CTL0_IOC			0x20000000	/* IRQ on complete */
 #define BGMAC_DESC_CTL0_EOF			0x40000000	/* End of frame */
 #define BGMAC_DESC_CTL0_SOF			0x80000000	/* Start of frame */
-#define BGMAC_DESC_CTL1_LEN			0x00001FFF
+#define BGMAC_DESC_CTL1_LEN			0x00003FFF
 
 #define BGMAC_PHY_NOREGS			BRCM_PSEUDO_PHY_ADDR
 #define BGMAC_PHY_MASK				0x1F
@@ -366,7 +366,8 @@
 #define BGMAC_RX_FRAME_OFFSET			30		/* There are 2 unused bytes between header and real data */
 #define BGMAC_RX_BUF_OFFSET			(NET_SKB_PAD + NET_IP_ALIGN - \
 						 BGMAC_RX_FRAME_OFFSET)
-#define BGMAC_RX_MAX_FRAME_SIZE			1536		/* Copied from b44/tg3 */
+/* Jumbo frame size with FCS */
+#define BGMAC_RX_MAX_FRAME_SIZE			9724
 #define BGMAC_RX_BUF_SIZE			(BGMAC_RX_FRAME_OFFSET + BGMAC_RX_MAX_FRAME_SIZE)
 #define BGMAC_RX_ALLOC_SIZE			(SKB_DATA_ALIGN(BGMAC_RX_BUF_SIZE + BGMAC_RX_BUF_OFFSET) + \
 						 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
-- 
2.17.1