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bcm4908: fix handling Ethernet frames of size 1506 - 1514

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MTU needs to be explicitly set as default value is too low.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
This commit is contained in:
Rafał Miłecki 2021-02-12 16:28:57 +01:00
parent 87efff6329
commit d8afae0be8
1 changed files with 113 additions and 0 deletions
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113
target/linux/bcm4908/patches-5.4/170-net-broadcom-bcm4908_enet-set-MTU-on-open-on-request.patch Normal file
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@ -0,0 +1,113 @@
From d7dfbcba0437955ccbe4c6db736526d528f27720 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Date: Fri, 12 Feb 2021 16:06:00 +0100
Subject: [PATCH] net: broadcom: bcm4908_enet: set MTU on open & on request
Hardware comes up with default max frame size set to 1518. When using it
with switch it results in actual Ethernet MTU 1492:
1518 - 14 (Ethernet header) - 4 (Broadcom's tag) - 4 (802.1q) - 4 (FCS)
Above means hardware in its default state can't handle standard Ethernet
traffic (MTU 1500).
Define maximum possible Ethernet overhead and always set MAC max frame
length accordingly. This change fixes handling Ethernet frames of length
1506 - 1514.
---
drivers/net/ethernet/broadcom/bcm4908_enet.c | 31 ++++++++++++++++----
1 file changed, 25 insertions(+), 6 deletions(-)
--- a/drivers/net/ethernet/broadcom/bcm4908_enet.c
+++ b/drivers/net/ethernet/broadcom/bcm4908_enet.c
@@ -5,6 +5,7 @@
#include <linux/delay.h>
#include <linux/etherdevice.h>
+#include <linux/if_vlan.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of.h>
@@ -29,9 +30,10 @@
ENET_DMA_CH_CFG_INT_BUFF_DONE)
#define ENET_DMA_MAX_BURST_LEN 8 /* in 64 bit words */
-#define ENET_MTU_MIN 60
-#define ENET_MTU_MAX 1500 /* Is it possible to support 2044? */
-#define ENET_MTU_MAX_EXTRA_SIZE 32 /* L2 */
+#define ENET_MTU_MAX ETH_DATA_LEN /* Is it possible to support 2044? */
+#define BRCM_MAX_TAG_LEN 6
+#define ENET_MAX_ETH_OVERHEAD (ETH_HLEN + BRCM_MAX_TAG_LEN + VLAN_HLEN + \
+ ETH_FCS_LEN + 4) /* 32 */
struct bcm4908_enet_dma_ring_bd {
__le32 ctl;
@@ -135,6 +137,11 @@ static void bcm4908_enet_intrs_ack(struc
enet_write(enet, ENET_DMA_CH_RX_CFG + ENET_DMA_CH_CFG_INT_STAT, ENET_DMA_INT_DEFAULTS);
}
+static void bcm4908_enet_set_mtu(struct bcm4908_enet *enet, int mtu)
+{
+ enet_umac_write(enet, UMAC_MAX_FRAME_LEN, mtu + ENET_MAX_ETH_OVERHEAD);
+}
+
/***
* DMA
*/
@@ -246,7 +253,7 @@ static int bcm4908_enet_dma_alloc_rx_buf
u32 tmp;
int err;
- slot->len = ENET_MTU_MAX + ENET_MTU_MAX_EXTRA_SIZE;
+ slot->len = ENET_MTU_MAX + ENET_MAX_ETH_OVERHEAD;
slot->skb = netdev_alloc_skb(enet->netdev, slot->len);
if (!slot->skb)
@@ -374,6 +381,8 @@ static void bcm4908_enet_gmac_init(struc
{
u32 cmd;
+ bcm4908_enet_set_mtu(enet, enet->netdev->mtu);
+
cmd = enet_umac_read(enet, UMAC_CMD);
enet_umac_write(enet, UMAC_CMD, cmd | CMD_SW_RESET);
enet_umac_write(enet, UMAC_CMD, cmd & ~CMD_SW_RESET);
@@ -559,7 +568,7 @@ static int bcm4908_enet_poll(struct napi
len = (ctl & DMA_CTL_LEN_DESC_BUFLENGTH) >> DMA_CTL_LEN_DESC_BUFLENGTH_SHIFT;
- if (len < ENET_MTU_MIN ||
+ if (len < ETH_ZLEN ||
(ctl & (DMA_CTL_STATUS_SOP | DMA_CTL_STATUS_EOP)) != (DMA_CTL_STATUS_SOP | DMA_CTL_STATUS_EOP)) {
enet->netdev->stats.rx_dropped++;
break;
@@ -583,11 +592,21 @@ static int bcm4908_enet_poll(struct napi
return handled;
}
+static int bcm4908_enet_change_mtu(struct net_device *netdev, int new_mtu)
+{
+ struct bcm4908_enet *enet = netdev_priv(netdev);
+
+ bcm4908_enet_set_mtu(enet, new_mtu);
+
+ return 0;
+}
+
static const struct net_device_ops bcm4908_enet_netdev_ops = {
.ndo_open = bcm4908_enet_open,
.ndo_stop = bcm4908_enet_stop,
.ndo_start_xmit = bcm4908_enet_start_xmit,
.ndo_set_mac_address = eth_mac_addr,
+ .ndo_change_mtu = bcm4908_enet_change_mtu,
};
static int bcm4908_enet_probe(struct platform_device *pdev)
@@ -625,7 +644,7 @@ static int bcm4908_enet_probe(struct pla
eth_hw_addr_random(netdev);
netdev->netdev_ops = &bcm4908_enet_netdev_ops;
netdev->min_mtu = ETH_ZLEN;
- netdev->mtu = ENET_MTU_MAX;
+ netdev->mtu = ETH_DATA_LEN;
netdev->max_mtu = ENET_MTU_MAX;
netif_napi_add(netdev, &enet->napi, bcm4908_enet_poll, 64);