kernel: mediatek: improve ethernet fix for dealing with small fragments

Replace the workaround on MT7986 with a proper fix. Software workaround is
still needed on older chips.

Signed-off-by: Felix Fietkau <nbd@nbd.name>

2 files changed, 37 insertions, 21 deletions

diff --git a/target/linux/generic/pending-5.15/732-10-net-ethernet-mtk_eth_soc-work-around-issue-with-send.patch b/target/linux/generic/pending-5.15/732-10-net-ethernet-mtk_eth_soc-work-around-issue-with-send.patch
index ba86686eeb..86ce481c2e 100644
--- a/target/linux/generic/pending-5.15/732-10-net-ethernet-mtk_eth_soc-work-around-issue-with-send.patch
+++ b/target/linux/generic/pending-5.15/732-10-net-ethernet-mtk_eth_soc-work-around-issue-with-send.patch
@@ -1,12 +1,15 @@
 From: Felix Fietkau <nbd@nbd.name>
 Date: Thu, 3 Nov 2022 12:38:49 +0100
-Subject: [PATCH] net: ethernet: mtk_eth_soc: work around issue with
- sending small fragments
+Subject: [PATCH] net: ethernet: mtk_eth_soc: work around issue with sending
+ small fragments
 
-When frames are sent with very small fragments, the DMA engine appears to
-lock up and transmit attempts time out. Fix this by detecting the presence
-of small fragments and use skb_gso_segment + skb_linearize to deal with
-them
+When lots of frames are sent with a number of very small fragments, an
+internal FIFO can overflow, causing the DMA engine to lock up lock up and
+transmit attempts time out.
+
+Fix this on MT7986 by increasing the reserved FIFO space.
+Fix this on older chips by detecting the presence of small fragments and use
+skb_gso_segment + skb_linearize to deal with them.
 
 Signed-off-by: Felix Fietkau <nbd@nbd.name>
 ---
@@ -42,11 +45,12 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
  	bool gso = false;
  	int tx_num;
  
-@@ -1423,6 +1439,17 @@ static netdev_tx_t mtk_start_xmit(struct
+@@ -1423,6 +1439,18 @@ static netdev_tx_t mtk_start_xmit(struct
  		return NETDEV_TX_BUSY;
  	}
  
-+	if (skb_is_gso(skb) && mtk_skb_has_small_frag(skb)) {
++	if (!MTK_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V2) &&
++	    skb_is_gso(skb) && mtk_skb_has_small_frag(skb)) {
 +		segs = skb_gso_segment(skb, dev->features & ~NETIF_F_ALL_TSO);
 +		if (IS_ERR(segs))
 +			goto drop;
@@ -60,19 +64,31 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
  	/* TSO: fill MSS info in tcp checksum field */
  	if (skb_is_gso(skb)) {
  		if (skb_cow_head(skb, 0)) {
-@@ -1438,8 +1465,13 @@ static netdev_tx_t mtk_start_xmit(struct
+@@ -1438,8 +1466,14 @@ static netdev_tx_t mtk_start_xmit(struct
  		}
  	}
  
 -	if (mtk_tx_map(skb, dev, tx_num, ring, gso) < 0)
 -		goto drop;
-+	skb_list_walk_safe(skb, skb, next) {
-+		if ((mtk_skb_has_small_frag(skb) && skb_linearize(skb)) ||
-+		    mtk_tx_map(skb, dev, tx_num, ring, gso) < 0) {
-+			stats->tx_dropped++;
-+			dev_kfree_skb_any(skb);
++	if (!MTK_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V2))
++		skb_list_walk_safe(skb, skb, next) {
++			if ((mtk_skb_has_small_frag(skb) && skb_linearize(skb)) ||
++			    mtk_tx_map(skb, dev, tx_num, ring, gso) < 0) {
++				stats->tx_dropped++;
++				dev_kfree_skb_any(skb);
++			}
 +		}
-+	}
  
  	if (unlikely(atomic_read(&ring->free_count) <= ring->thresh))
  		netif_tx_stop_all_queues(dev);
+--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
++++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+@@ -246,7 +246,7 @@
+ #define MTK_CHK_DDONE_EN	BIT(28)
+ #define MTK_DMAD_WR_WDONE	BIT(26)
+ #define MTK_WCOMP_EN		BIT(24)
+-#define MTK_RESV_BUF		(0x40 << 16)
++#define MTK_RESV_BUF		(0x80 << 16)
+ #define MTK_MUTLI_CNT		(0x4 << 12)
+ #define MTK_LEAKY_BUCKET_EN	BIT(11)
+ 
diff --git a/target/linux/generic/pending-5.15/732-14-net-ethernet-mtk_eth_soc-drop-generic-vlan-rx-offloa.patch b/target/linux/generic/pending-5.15/732-14-net-ethernet-mtk_eth_soc-drop-generic-vlan-rx-offloa.patch
index c3a879e5ab..0d575b84a0 100644
--- a/target/linux/generic/pending-5.15/732-14-net-ethernet-mtk_eth_soc-drop-generic-vlan-rx-offloa.patch
+++ b/target/linux/generic/pending-5.15/732-14-net-ethernet-mtk_eth_soc-drop-generic-vlan-rx-offloa.patch
@@ -17,7 +17,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
 
 --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
 +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
-@@ -1993,29 +1993,16 @@ static int mtk_poll_rx(struct napi_struc
+@@ -1995,29 +1995,16 @@ static int mtk_poll_rx(struct napi_struc
  		if (reason == MTK_PPE_CPU_REASON_HIT_UNBIND_RATE_REACHED)
  			mtk_ppe_check_skb(eth->ppe[0], skb, hash);
  
@@ -50,7 +50,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
  		}
  
  		skb_record_rx_queue(skb, 0);
-@@ -2832,29 +2819,11 @@ static netdev_features_t mtk_fix_feature
+@@ -2834,29 +2821,11 @@ static netdev_features_t mtk_fix_feature
  
  static int mtk_set_features(struct net_device *dev, netdev_features_t features)
  {
@@ -80,7 +80,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
  	return 0;
  }
  
-@@ -3153,30 +3122,6 @@ static int mtk_open(struct net_device *d
+@@ -3155,30 +3124,6 @@ static int mtk_open(struct net_device *d
  	struct mtk_eth *eth = mac->hw;
  	int i, err;
  
@@ -111,7 +111,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
  	err = phylink_of_phy_connect(mac->phylink, mac->of_node, 0);
  	if (err) {
  		netdev_err(dev, "%s: could not attach PHY: %d\n", __func__,
-@@ -3217,6 +3162,35 @@ static int mtk_open(struct net_device *d
+@@ -3219,6 +3164,35 @@ static int mtk_open(struct net_device *d
  	phylink_start(mac->phylink);
  	netif_tx_start_all_queues(dev);
  
@@ -147,7 +147,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
  	return 0;
  }
  
-@@ -3510,10 +3484,9 @@ static int mtk_hw_init(struct mtk_eth *e
+@@ -3512,10 +3486,9 @@ static int mtk_hw_init(struct mtk_eth *e
  	if (!MTK_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V2)) {
  		val = mtk_r32(eth, MTK_CDMP_IG_CTRL);
  		mtk_w32(eth, val | MTK_CDMP_STAG_EN, MTK_CDMP_IG_CTRL);
@@ -160,7 +160,7 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
  
  	/* set interrupt delays based on current Net DIM sample */
  	mtk_dim_rx(&eth->rx_dim.work);
-@@ -4134,7 +4107,7 @@ static int mtk_add_mac(struct mtk_eth *e
+@@ -4136,7 +4109,7 @@ static int mtk_add_mac(struct mtk_eth *e
  		eth->netdev[id]->hw_features |= NETIF_F_LRO;
  
  	eth->netdev[id]->vlan_features = eth->soc->hw_features &