ramips: add mt7621 ethernet driver improvements

- Speed up MDIO bus access
- Improve performance on tx completion

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

target/linux/ramips/patches-5.4/0400-net-ethernet-mediatek-use-napi_consume_skb.patch

@@ -0,0 +1,72 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Mon, 8 Jun 2020 17:01:12 +0200
+Subject: [PATCH] net: ethernet: mediatek: use napi_consume_skb
+
+Should improve performance, since it can use bulk free
+
+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
+@@ -844,7 +844,8 @@ static int txd_to_idx(struct mtk_tx_ring
+ 	return ((void *)dma - (void *)ring->dma) / sizeof(*dma);
+ }
+ 
+-static void mtk_tx_unmap(struct mtk_eth *eth, struct mtk_tx_buf *tx_buf)
++static void mtk_tx_unmap(struct mtk_eth *eth, struct mtk_tx_buf *tx_buf,
++			 bool napi)
+ {
+ 	if (MTK_HAS_CAPS(eth->soc->caps, MTK_QDMA)) {
+ 		if (tx_buf->flags & MTK_TX_FLAGS_SINGLE0) {
+@@ -876,8 +877,12 @@ static void mtk_tx_unmap(struct mtk_eth
+ 
+ 	tx_buf->flags = 0;
+ 	if (tx_buf->skb &&
+-	    (tx_buf->skb != (struct sk_buff *)MTK_DMA_DUMMY_DESC))
+-		dev_kfree_skb_any(tx_buf->skb);
++	    (tx_buf->skb != (struct sk_buff *)MTK_DMA_DUMMY_DESC)) {
++		if (napi)
++			napi_consume_skb(tx_buf->skb, napi);
++		else
++			dev_kfree_skb_any(tx_buf->skb);
++	}
+ 	tx_buf->skb = NULL;
+ }
+ 
+@@ -1055,7 +1060,7 @@ err_dma:
+ 		tx_buf = mtk_desc_to_tx_buf(ring, itxd);
+ 
+ 		/* unmap dma */
+-		mtk_tx_unmap(eth, tx_buf);
++		mtk_tx_unmap(eth, tx_buf, false);
+ 
+ 		itxd->txd3 = TX_DMA_LS0 | TX_DMA_OWNER_CPU;
+ 		if (!MTK_HAS_CAPS(eth->soc->caps, MTK_QDMA))
+@@ -1373,7 +1378,7 @@ static int mtk_poll_tx_qdma(struct mtk_e
+ 			done[mac]++;
+ 			budget--;
+ 		}
+-		mtk_tx_unmap(eth, tx_buf);
++		mtk_tx_unmap(eth, tx_buf, true);
+ 
+ 		ring->last_free = desc;
+ 		atomic_inc(&ring->free_count);
+@@ -1410,7 +1415,7 @@ static int mtk_poll_tx_pdma(struct mtk_e
+ 			budget--;
+ 		}
+ 
+-		mtk_tx_unmap(eth, tx_buf);
++		mtk_tx_unmap(eth, tx_buf, true);
+ 
+ 		desc = &ring->dma[cpu];
+ 		ring->last_free = desc;
+@@ -1612,7 +1617,7 @@ static void mtk_tx_clean(struct mtk_eth
+ 
+ 	if (ring->buf) {
+ 		for (i = 0; i < MTK_DMA_SIZE; i++)
+-			mtk_tx_unmap(eth, &ring->buf[i]);
++			mtk_tx_unmap(eth, &ring->buf[i], false);
+ 		kfree(ring->buf);
+ 		ring->buf = NULL;
+ 	}

target/linux/ramips/patches-5.4/0401-net-ethernet-mediatek-significantly-reduce-mdio-bus-.patch

@@ -0,0 +1,26 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Mon, 8 Jun 2020 17:02:39 +0200
+Subject: [PATCH] net: ethernet: mediatek: significantly reduce mdio bus
+ access latency
+
+usleep_range often ends up sleeping much longer than the 10-20us provided
+as a range here. This causes significant latency in mdio bus acceses,
+which easily adds multiple seconds to the boot time on MT7621 when polling
+DSA slave ports.
+Use cond_resched instead of usleep_range, since the MDIO access does not
+take much time
+
+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
+@@ -85,7 +85,7 @@ static int mtk_mdio_busy_wait(struct mtk
+ 			return 0;
+ 		if (time_after(jiffies, t_start + PHY_IAC_TIMEOUT))
+ 			break;
+-		usleep_range(10, 20);
++		cond_resched();
+ 	}
+ 
+ 	dev_err(eth->dev, "mdio: MDIO timeout\n");