From c57e558194430d10d5e5f4acd8a8655b68dade13 Mon Sep 17 00:00:00 2001
From: Frank Wunderlich <frank-w@public-files.de>
Date: Mon, 3 Jun 2024 21:25:05 +0200
Subject: [PATCH] net: ethernet: mtk_eth_soc: handle dma buffer size soc
 specific

The mainline MTK ethernet driver suffers long time from rarly but
annoying tx queue timeouts. We think that this is caused by fixed
dma sizes hardcoded for all SoCs.

We suspect this problem arises from a low level of free TX DMADs,
the TX Ring alomost full.

The transmit timeout is caused by the Tx queue not waking up. The
Tx queue stops when the free counter is less than ring->thres, and
it will wake up once the free counter is greater than ring->thres.
If the CPU is too late to wake up the Tx queues, it may cause a
transmit timeout.
Therefore, we increased the TX and RX DMADs to improve this error
situation.

Use the dma-size implementation from SDK in a per SoC manner. In
difference to SDK we have no RSS feature yet, so all RX/TX sizes
should be raised from 512 to 2048 byte except fqdma on mt7988 to
avoid the tx timeout issue.

Fixes: 656e705243fd ("net-next: mediatek: add support for MT7623 ethernet")
Suggested-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 104 +++++++++++++-------
 drivers/net/ethernet/mediatek/mtk_eth_soc.h |   9 +-
 2 files changed, 77 insertions(+), 36 deletions(-)

--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -1131,9 +1131,9 @@ static int mtk_init_fq_dma(struct mtk_et
 {
 	const struct mtk_soc_data *soc = eth->soc;
 	dma_addr_t phy_ring_tail;
-	int cnt = MTK_QDMA_RING_SIZE;
+	int cnt = soc->tx.fq_dma_size;
 	dma_addr_t dma_addr;
-	int i;
+	int i, j, len;
 
 	if (MTK_HAS_CAPS(eth->soc->caps, MTK_SRAM))
 		eth->scratch_ring = eth->sram_base;
@@ -1142,40 +1142,46 @@ static int mtk_init_fq_dma(struct mtk_et
 						       cnt * soc->tx.desc_size,
 						       &eth->phy_scratch_ring,
 						       GFP_KERNEL);
+
 	if (unlikely(!eth->scratch_ring))
 		return -ENOMEM;
 
-	eth->scratch_head = kcalloc(cnt, MTK_QDMA_PAGE_SIZE, GFP_KERNEL);
-	if (unlikely(!eth->scratch_head))
-		return -ENOMEM;
+	phy_ring_tail = eth->phy_scratch_ring + soc->tx.desc_size * (cnt - 1);
 
-	dma_addr = dma_map_single(eth->dma_dev,
-				  eth->scratch_head, cnt * MTK_QDMA_PAGE_SIZE,
-				  DMA_FROM_DEVICE);
-	if (unlikely(dma_mapping_error(eth->dma_dev, dma_addr)))
-		return -ENOMEM;
+	for (j = 0; j < DIV_ROUND_UP(soc->tx.fq_dma_size, MTK_FQ_DMA_LENGTH); j++) {
+		len = min_t(int, cnt - j * MTK_FQ_DMA_LENGTH, MTK_FQ_DMA_LENGTH);
+		eth->scratch_head[j] = kcalloc(len, MTK_QDMA_PAGE_SIZE, GFP_KERNEL);
 
-	phy_ring_tail = eth->phy_scratch_ring + soc->tx.desc_size * (cnt - 1);
+		if (unlikely(!eth->scratch_head[j]))
+			return -ENOMEM;
 
-	for (i = 0; i < cnt; i++) {
-		dma_addr_t addr = dma_addr + i * MTK_QDMA_PAGE_SIZE;
-		struct mtk_tx_dma_v2 *txd;
-
-		txd = eth->scratch_ring + i * soc->tx.desc_size;
-		txd->txd1 = addr;
-		if (i < cnt - 1)
-			txd->txd2 = eth->phy_scratch_ring +
-				    (i + 1) * soc->tx.desc_size;
-
-		txd->txd3 = TX_DMA_PLEN0(MTK_QDMA_PAGE_SIZE);
-		if (MTK_HAS_CAPS(soc->caps, MTK_36BIT_DMA))
-			txd->txd3 |= TX_DMA_PREP_ADDR64(addr);
-		txd->txd4 = 0;
-		if (mtk_is_netsys_v2_or_greater(eth)) {
-			txd->txd5 = 0;
-			txd->txd6 = 0;
-			txd->txd7 = 0;
-			txd->txd8 = 0;
+		dma_addr = dma_map_single(eth->dma_dev,
+					  eth->scratch_head[j], len * MTK_QDMA_PAGE_SIZE,
+					  DMA_FROM_DEVICE);
+
+		if (unlikely(dma_mapping_error(eth->dma_dev, dma_addr)))
+			return -ENOMEM;
+
+		for (i = 0; i < cnt; i++) {
+			struct mtk_tx_dma_v2 *txd;
+
+			txd = eth->scratch_ring + (j * MTK_FQ_DMA_LENGTH + i) * soc->tx.desc_size;
+			txd->txd1 = dma_addr + i * MTK_QDMA_PAGE_SIZE;
+			if (j * MTK_FQ_DMA_LENGTH + i < cnt)
+				txd->txd2 = eth->phy_scratch_ring +
+					    (j * MTK_FQ_DMA_LENGTH + i + 1) * soc->tx.desc_size;
+
+			txd->txd3 = TX_DMA_PLEN0(MTK_QDMA_PAGE_SIZE);
+			if (MTK_HAS_CAPS(soc->caps, MTK_36BIT_DMA))
+				txd->txd3 |= TX_DMA_PREP_ADDR64(dma_addr + i * MTK_QDMA_PAGE_SIZE);
+
+			txd->txd4 = 0;
+			if (mtk_is_netsys_v2_or_greater(eth)) {
+				txd->txd5 = 0;
+				txd->txd6 = 0;
+				txd->txd7 = 0;
+				txd->txd8 = 0;
+			}
 		}
 	}
 
@@ -2469,7 +2475,7 @@ static int mtk_tx_alloc(struct mtk_eth *
 	if (MTK_HAS_CAPS(soc->caps, MTK_QDMA))
 		ring_size = MTK_QDMA_RING_SIZE;
 	else
-		ring_size = MTK_DMA_SIZE;
+		ring_size = soc->tx.dma_size;
 
 	ring->buf = kcalloc(ring_size, sizeof(*ring->buf),
 			       GFP_KERNEL);
@@ -2477,8 +2483,8 @@ static int mtk_tx_alloc(struct mtk_eth *
 		goto no_tx_mem;
 
 	if (MTK_HAS_CAPS(soc->caps, MTK_SRAM)) {
-		ring->dma = eth->sram_base + ring_size * sz;
-		ring->phys = eth->phy_scratch_ring + ring_size * (dma_addr_t)sz;
+		ring->dma = eth->sram_base + soc->tx.fq_dma_size * sz;
+		ring->phys = eth->phy_scratch_ring + soc->tx.fq_dma_size * (dma_addr_t)sz;
 	} else {
 		ring->dma = dma_alloc_coherent(eth->dma_dev, ring_size * sz,
 					       &ring->phys, GFP_KERNEL);
@@ -2600,6 +2606,7 @@ static void mtk_tx_clean(struct mtk_eth
 static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
 {
 	const struct mtk_reg_map *reg_map = eth->soc->reg_map;
+	const struct mtk_soc_data *soc = eth->soc;
 	struct mtk_rx_ring *ring;
 	int rx_data_len, rx_dma_size, tx_ring_size;
 	int i;
@@ -2607,7 +2614,7 @@ static int mtk_rx_alloc(struct mtk_eth *
 	if (MTK_HAS_CAPS(eth->soc->caps, MTK_QDMA))
 		tx_ring_size = MTK_QDMA_RING_SIZE;
 	else
-		tx_ring_size = MTK_DMA_SIZE;
+		tx_ring_size = soc->tx.dma_size;
 
 	if (rx_flag == MTK_RX_FLAGS_QDMA) {
 		if (ring_no)
@@ -2622,7 +2629,7 @@ static int mtk_rx_alloc(struct mtk_eth *
 		rx_dma_size = MTK_HW_LRO_DMA_SIZE;
 	} else {
 		rx_data_len = ETH_DATA_LEN;
-		rx_dma_size = MTK_DMA_SIZE;
+		rx_dma_size = soc->rx.dma_size;
 	}
 
 	ring->frag_size = mtk_max_frag_size(rx_data_len);
@@ -3159,7 +3166,10 @@ static void mtk_dma_free(struct mtk_eth
 			mtk_rx_clean(eth, &eth->rx_ring[i], false);
 	}
 
-	kfree(eth->scratch_head);
+	for (i = 0; i < DIV_ROUND_UP(soc->tx.fq_dma_size, MTK_FQ_DMA_LENGTH); i++) {
+		kfree(eth->scratch_head[i]);
+		eth->scratch_head[i] = NULL;
+	}
 }
 
 static bool mtk_hw_reset_check(struct mtk_eth *eth)
@@ -5081,11 +5091,14 @@ static const struct mtk_soc_data mt2701_
 		.desc_size = sizeof(struct mtk_tx_dma),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
+		.dma_size = MTK_DMA_SIZE(2K),
+		.fq_dma_size = MTK_DMA_SIZE(2K),
 	},
 	.rx = {
 		.desc_size = sizeof(struct mtk_rx_dma),
 		.irq_done_mask = MTK_RX_DONE_INT,
 		.dma_l4_valid = RX_DMA_L4_VALID,
+		.dma_size = MTK_DMA_SIZE(2K),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
 	},
@@ -5105,11 +5118,14 @@ static const struct mtk_soc_data mt7621_
 		.desc_size = sizeof(struct mtk_tx_dma),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
+		.dma_size = MTK_DMA_SIZE(2K),
+		.fq_dma_size = MTK_DMA_SIZE(2K),
 	},
 	.rx = {
 		.desc_size = sizeof(struct mtk_rx_dma),
 		.irq_done_mask = MTK_RX_DONE_INT,
 		.dma_l4_valid = RX_DMA_L4_VALID,
+		.dma_size = MTK_DMA_SIZE(2K),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
 	},
@@ -5131,11 +5147,14 @@ static const struct mtk_soc_data mt7622_
 		.desc_size = sizeof(struct mtk_tx_dma),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
+		.dma_size = MTK_DMA_SIZE(2K),
+		.fq_dma_size = MTK_DMA_SIZE(2K),
 	},
 	.rx = {
 		.desc_size = sizeof(struct mtk_rx_dma),
 		.irq_done_mask = MTK_RX_DONE_INT,
 		.dma_l4_valid = RX_DMA_L4_VALID,
+		.dma_size = MTK_DMA_SIZE(2K),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
 	},
@@ -5156,11 +5175,14 @@ static const struct mtk_soc_data mt7623_
 		.desc_size = sizeof(struct mtk_tx_dma),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
+		.dma_size = MTK_DMA_SIZE(2K),
+		.fq_dma_size = MTK_DMA_SIZE(2K),
 	},
 	.rx = {
 		.desc_size = sizeof(struct mtk_rx_dma),
 		.irq_done_mask = MTK_RX_DONE_INT,
 		.dma_l4_valid = RX_DMA_L4_VALID,
+		.dma_size = MTK_DMA_SIZE(2K),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
 	},
@@ -5179,11 +5201,14 @@ static const struct mtk_soc_data mt7629_
 		.desc_size = sizeof(struct mtk_tx_dma),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
+		.dma_size = MTK_DMA_SIZE(2K),
+		.fq_dma_size = MTK_DMA_SIZE(2K),
 	},
 	.rx = {
 		.desc_size = sizeof(struct mtk_rx_dma),
 		.irq_done_mask = MTK_RX_DONE_INT,
 		.dma_l4_valid = RX_DMA_L4_VALID,
+		.dma_size = MTK_DMA_SIZE(2K),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
 	},
@@ -5205,6 +5230,8 @@ static const struct mtk_soc_data mt7981_
 		.desc_size = sizeof(struct mtk_tx_dma_v2),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN_V2,
 		.dma_len_offset = 8,
+		.dma_size = MTK_DMA_SIZE(2K),
+		.fq_dma_size = MTK_DMA_SIZE(2K),
 	},
 	.rx = {
 		.desc_size = sizeof(struct mtk_rx_dma),
@@ -5212,6 +5239,7 @@ static const struct mtk_soc_data mt7981_
 		.dma_l4_valid = RX_DMA_L4_VALID_V2,
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
+		.dma_size = MTK_DMA_SIZE(2K),
 	},
 };
 
@@ -5231,6 +5259,8 @@ static const struct mtk_soc_data mt7986_
 		.desc_size = sizeof(struct mtk_tx_dma_v2),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN_V2,
 		.dma_len_offset = 8,
+		.dma_size = MTK_DMA_SIZE(2K),
+		.fq_dma_size = MTK_DMA_SIZE(2K),
 	},
 	.rx = {
 		.desc_size = sizeof(struct mtk_rx_dma),
@@ -5238,6 +5268,7 @@ static const struct mtk_soc_data mt7986_
 		.dma_l4_valid = RX_DMA_L4_VALID_V2,
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
+		.dma_size = MTK_DMA_SIZE(2K),
 	},
 };
 
@@ -5257,6 +5288,8 @@ static const struct mtk_soc_data mt7988_
 		.desc_size = sizeof(struct mtk_tx_dma_v2),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN_V2,
 		.dma_len_offset = 8,
+		.dma_size = MTK_DMA_SIZE(2K),
+		.fq_dma_size = MTK_DMA_SIZE(4K),
 	},
 	.rx = {
 		.desc_size = sizeof(struct mtk_rx_dma_v2),
@@ -5264,6 +5297,7 @@ static const struct mtk_soc_data mt7988_
 		.dma_l4_valid = RX_DMA_L4_VALID_V2,
 		.dma_max_len = MTK_TX_DMA_BUF_LEN_V2,
 		.dma_len_offset = 8,
+		.dma_size = MTK_DMA_SIZE(2K),
 	},
 };
 
@@ -5278,6 +5312,7 @@ static const struct mtk_soc_data rt5350_
 		.desc_size = sizeof(struct mtk_tx_dma),
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
+		.dma_size = MTK_DMA_SIZE(2K),
 	},
 	.rx = {
 		.desc_size = sizeof(struct mtk_rx_dma),
@@ -5285,6 +5320,7 @@ static const struct mtk_soc_data rt5350_
 		.dma_l4_valid = RX_DMA_L4_VALID_PDMA,
 		.dma_max_len = MTK_TX_DMA_BUF_LEN,
 		.dma_len_offset = 16,
+		.dma_size = MTK_DMA_SIZE(2K),
 	},
 };
 
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -32,7 +32,9 @@
 #define MTK_TX_DMA_BUF_LEN	0x3fff
 #define MTK_TX_DMA_BUF_LEN_V2	0xffff
 #define MTK_QDMA_RING_SIZE	2048
-#define MTK_DMA_SIZE		512
+#define MTK_DMA_SIZE(x)		(SZ_##x)
+#define MTK_FQ_DMA_HEAD		32
+#define MTK_FQ_DMA_LENGTH	2048
 #define MTK_RX_ETH_HLEN		(ETH_HLEN + ETH_FCS_LEN)
 #define MTK_RX_HLEN		(NET_SKB_PAD + MTK_RX_ETH_HLEN + NET_IP_ALIGN)
 #define MTK_DMA_DUMMY_DESC	0xffffffff
@@ -1184,6 +1186,8 @@ struct mtk_soc_data {
 		u32	desc_size;
 		u32	dma_max_len;
 		u32	dma_len_offset;
+		u32	dma_size;
+		u32	fq_dma_size;
 	} tx;
 	struct {
 		u32	desc_size;
@@ -1191,6 +1195,7 @@ struct mtk_soc_data {
 		u32	dma_l4_valid;
 		u32	dma_max_len;
 		u32	dma_len_offset;
+		u32	dma_size;
 	} rx;
 };
 
@@ -1272,7 +1277,7 @@ struct mtk_eth {
 	struct napi_struct		rx_napi;
 	void				*scratch_ring;
 	dma_addr_t			phy_scratch_ring;
-	void				*scratch_head;
+	void				*scratch_head[MTK_FQ_DMA_HEAD];
 	struct clk			*clks[MTK_CLK_MAX];
 
 	struct mii_bus			*mii_bus;
