From: Mathias Kresin <dev@kresin.me>
Date: Sun, 18 Feb 2018 21:48:44 +0000 (+0100)
Subject: ramips: mt7621: fix mtu setting with kernel 4.14
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=b81774cff80718d20982649c4f21a405fa71a07c;p=openwrt%2Fstaging%2Fdedeckeh.git

ramips: mt7621: fix mtu setting with kernel 4.14

Since kernel 4.10 commit 61e84623ace3 ("net: centralize net_device
min/max MTU checking"), the range of mtu is [min_mtu, max_mtu], which
is [68, 1500] by default.

It's necessary to set a max_mtu if a mtu > 1500 is supported.

Signed-off-by: Mathias Kresin <dev@kresin.me>
(backported from 5da2c68d001ee44b15a58639ed03a0ebb6f68020)
---

diff --git a/target/linux/ramips/files-4.14/drivers/net/ethernet/mtk/mtk_eth_soc.c b/target/linux/ramips/files-4.14/drivers/net/ethernet/mtk/mtk_eth_soc.c
index 6eae661ecf..74639cbb68 100644
--- a/target/linux/ramips/files-4.14/drivers/net/ethernet/mtk/mtk_eth_soc.c
+++ b/target/linux/ramips/files-4.14/drivers/net/ethernet/mtk/mtk_eth_soc.c
@@ -1384,20 +1384,12 @@ static int fe_change_mtu(struct net_device *dev, int new_mtu)
 	int frag_size, old_mtu;
 	u32 fwd_cfg;
 
-	if (!(priv->flags & FE_FLAG_JUMBO_FRAME))
-		return eth_change_mtu(dev, new_mtu);
-
-	if (IS_ENABLED(CONFIG_SOC_MT7621))
-		if (new_mtu > 2048)
-			return -EINVAL;
-
-	frag_size = fe_max_frag_size(new_mtu);
-	if (new_mtu < 68 || frag_size > PAGE_SIZE)
-		return -EINVAL;
-
 	old_mtu = dev->mtu;
 	dev->mtu = new_mtu;
 
+	if (!(priv->flags & FE_FLAG_JUMBO_FRAME))
+		return 0;
+
 	/* return early if the buffer sizes will not change */
 	if (old_mtu <= ETH_DATA_LEN && new_mtu <= ETH_DATA_LEN)
 		return 0;
@@ -1419,6 +1411,7 @@ static int fe_change_mtu(struct net_device *dev, int new_mtu)
 		if (new_mtu <= ETH_DATA_LEN) {
 			fwd_cfg &= ~FE_GDM1_JMB_EN;
 		} else {
+			frag_size = fe_max_frag_size(new_mtu);
 			fwd_cfg &= ~(FE_GDM1_JMB_LEN_MASK << FE_GDM1_JMB_LEN_SHIFT);
 			fwd_cfg |= (DIV_ROUND_UP(frag_size, 1024) <<
 			FE_GDM1_JMB_LEN_SHIFT) | FE_GDM1_JMB_EN;
@@ -1552,6 +1545,9 @@ static int fe_probe(struct platform_device *pdev)
 	netdev->vlan_features = netdev->hw_features & ~NETIF_F_HW_VLAN_CTAG_TX;
 	netdev->features |= netdev->hw_features;
 
+	if (IS_ENABLED(CONFIG_SOC_MT7621))
+		netdev->max_mtu = 2048;
+
 	/* fake rx vlan filter func. to support tx vlan offload func */
 	if (fe_reg_table[FE_REG_FE_DMA_VID_BASE])
 		netdev->features |= NETIF_F_HW_VLAN_CTAG_FILTER;