kernel: move accepted mtk_eth_soc patches to generic-backport

[openwrt/openwrt.git] / target / linux / generic / pending-5.15 / 732-01-net-ethernet-mtk_eth_soc-work-around-issue-with-send.patch

diff --git a/target/linux/generic/pending-5.15/732-01-net-ethernet-mtk_eth_soc-work-around-issue-with-send.patch b/target/linux/generic/pending-5.15/732-01-net-ethernet-mtk_eth_soc-work-around-issue-with-send.patch
new file mode 100644 (file)
index 0000000..777e6f0
--- /dev/null
+++ b/target/linux/generic/pending-5.15/732-01-net-ethernet-mtk_eth_soc-work-around-issue-with-send.patch
@@ -0,0 +1,94 @@
+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
+
+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>
+---
+
+--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
++++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+@@ -1402,12 +1402,28 @@ static void mtk_wake_queue(struct mtk_et
+       }
+ }
+ 
++static bool mtk_skb_has_small_frag(struct sk_buff *skb)
++{
++      int min_size = 16;
++      int i;
++
++      if (skb_headlen(skb) < min_size)
++              return true;
++
++      for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
++              if (skb_frag_size(&skb_shinfo(skb)->frags[i]) < min_size)
++                      return true;
++
++      return false;
++}
++
+ static netdev_tx_t mtk_start_xmit(struct sk_buff *skb, struct net_device *dev)
+ {
+       struct mtk_mac *mac = netdev_priv(dev);
+       struct mtk_eth *eth = mac->hw;
+       struct mtk_tx_ring *ring = &eth->tx_ring;
+       struct net_device_stats *stats = &dev->stats;
++      struct sk_buff *segs, *next;
+       bool gso = false;
+       int tx_num;
+ 
+@@ -1429,6 +1445,18 @@ static netdev_tx_t mtk_start_xmit(struct
+               return NETDEV_TX_BUSY;
+       }
+ 
++      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;
++
++              if (segs) {
++                      consume_skb(skb);
++                      skb = segs;
++              }
++      }
++
+       /* TSO: fill MSS info in tcp checksum field */
+       if (skb_is_gso(skb)) {
+               if (skb_cow_head(skb, 0)) {
+@@ -1444,8 +1472,14 @@ 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_HAS_CAPS(eth->soc->caps, MTK_NETSYS_V2) &&
++                   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
+@@ -258,7 +258,7 @@
+ #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)
+