Subject: [PATCH] net: ethernet: mtk_eth_soc: increase tx ring side for QDMA devices
From: Felix Fietkau <[email-masked]>
Date: Thu, 27 Oct 2022 19:53:57 +0200

In order to use the hardware traffic shaper feature, a larger tx ring is
needed, especially for the scratch ring, which the hardware shaper uses to
reorder packets.

Signed-off-by: Felix Fietkau <[email-masked]>
---

--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -900,7 +900,7 @@ 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_DMA_SIZE;
+	int cnt = MTK_QDMA_RING_SIZE;
 	dma_addr_t dma_addr;
 	int i;
 
@@ -2154,19 +2154,25 @@ static int mtk_tx_alloc(struct mtk_eth *
 	struct mtk_tx_ring *ring = &eth->tx_ring;
 	int i, sz = soc->txrx.txd_size;
 	struct mtk_tx_dma_v2 *txd;
+	int ring_size;
 
-	ring->buf = kcalloc(MTK_DMA_SIZE, sizeof(*ring->buf),
+	if (MTK_HAS_CAPS(soc->caps, MTK_QDMA))
+		ring_size = MTK_QDMA_RING_SIZE;
+	else
+		ring_size = MTK_DMA_SIZE;
+
+	ring->buf = kcalloc(ring_size, sizeof(*ring->buf),
 			       GFP_KERNEL);
 	if (!ring->buf)
 		goto no_tx_mem;
 
-	ring->dma = dma_alloc_coherent(eth->dma_dev, MTK_DMA_SIZE * sz,
+	ring->dma = dma_alloc_coherent(eth->dma_dev, ring_size * sz,
 				       &ring->phys, GFP_KERNEL);
 	if (!ring->dma)
 		goto no_tx_mem;
 
-	for (i = 0; i < MTK_DMA_SIZE; i++) {
-		int next = (i + 1) % MTK_DMA_SIZE;
+	for (i = 0; i < ring_size; i++) {
+		int next = (i + 1) % ring_size;
 		u32 next_ptr = ring->phys + next * sz;
 
 		txd = ring->dma + i * sz;
@@ -2186,22 +2192,22 @@ static int mtk_tx_alloc(struct mtk_eth *
 	 * descriptors in ring->dma_pdma.
 	 */
 	if (!MTK_HAS_CAPS(soc->caps, MTK_QDMA)) {
-		ring->dma_pdma = dma_alloc_coherent(eth->dma_dev, MTK_DMA_SIZE * sz,
+		ring->dma_pdma = dma_alloc_coherent(eth->dma_dev, ring_size * sz,
 						    &ring->phys_pdma, GFP_KERNEL);
 		if (!ring->dma_pdma)
 			goto no_tx_mem;
 
-		for (i = 0; i < MTK_DMA_SIZE; i++) {
+		for (i = 0; i < ring_size; i++) {
 			ring->dma_pdma[i].txd2 = TX_DMA_DESP2_DEF;
 			ring->dma_pdma[i].txd4 = 0;
 		}
 	}
 
-	ring->dma_size = MTK_DMA_SIZE;
-	atomic_set(&ring->free_count, MTK_DMA_SIZE - 2);
+	ring->dma_size = ring_size;
+	atomic_set(&ring->free_count, ring_size - 2);
 	ring->next_free = ring->dma;
 	ring->last_free = (void *)txd;
-	ring->last_free_ptr = (u32)(ring->phys + ((MTK_DMA_SIZE - 1) * sz));
+	ring->last_free_ptr = (u32)(ring->phys + ((ring_size - 1) * sz));
 	ring->thresh = MAX_SKB_FRAGS;
 
 	/* make sure that all changes to the dma ring are flushed before we
@@ -2213,14 +2219,14 @@ static int mtk_tx_alloc(struct mtk_eth *
 		mtk_w32(eth, ring->phys, soc->reg_map->qdma.ctx_ptr);
 		mtk_w32(eth, ring->phys, soc->reg_map->qdma.dtx_ptr);
 		mtk_w32(eth,
-			ring->phys + ((MTK_DMA_SIZE - 1) * sz),
+			ring->phys + ((ring_size - 1) * sz),
 			soc->reg_map->qdma.crx_ptr);
 		mtk_w32(eth, ring->last_free_ptr, soc->reg_map->qdma.drx_ptr);
 		mtk_w32(eth, (QDMA_RES_THRES << 8) | QDMA_RES_THRES,
 			soc->reg_map->qdma.qtx_cfg);
 	} else {
 		mtk_w32(eth, ring->phys_pdma, MT7628_TX_BASE_PTR0);
-		mtk_w32(eth, MTK_DMA_SIZE, MT7628_TX_MAX_CNT0);
+		mtk_w32(eth, ring_size, MT7628_TX_MAX_CNT0);
 		mtk_w32(eth, 0, MT7628_TX_CTX_IDX0);
 		mtk_w32(eth, MT7628_PST_DTX_IDX0, soc->reg_map->pdma.rst_idx);
 	}
@@ -2238,7 +2244,7 @@ static void mtk_tx_clean(struct mtk_eth
 	int i;
 
 	if (ring->buf) {
-		for (i = 0; i < MTK_DMA_SIZE; i++)
+		for (i = 0; i < ring->dma_size; i++)
 			mtk_tx_unmap(eth, &ring->buf[i], false);
 		kfree(ring->buf);
 		ring->buf = NULL;
@@ -2246,14 +2252,14 @@ static void mtk_tx_clean(struct mtk_eth
 
 	if (ring->dma) {
 		dma_free_coherent(eth->dma_dev,
-				  MTK_DMA_SIZE * soc->txrx.txd_size,
+				  ring->dma_size * soc->txrx.txd_size,
 				  ring->dma, ring->phys);
 		ring->dma = NULL;
 	}
 
 	if (ring->dma_pdma) {
 		dma_free_coherent(eth->dma_dev,
-				  MTK_DMA_SIZE * soc->txrx.txd_size,
+				  ring->dma_size * soc->txrx.txd_size,
 				  ring->dma_pdma, ring->phys_pdma);
 		ring->dma_pdma = NULL;
 	}
@@ -2776,7 +2782,7 @@ static void mtk_dma_free(struct mtk_eth
 			netdev_reset_queue(eth->netdev[i]);
 	if (eth->scratch_ring) {
 		dma_free_coherent(eth->dma_dev,
-				  MTK_DMA_SIZE * soc->txrx.txd_size,
+				  MTK_QDMA_RING_SIZE * soc->txrx.txd_size,
 				  eth->scratch_ring, eth->phy_scratch_ring);
 		eth->scratch_ring = NULL;
 		eth->phy_scratch_ring = 0;
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.h
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.h
@@ -27,6 +27,7 @@
 #define MTK_MAX_RX_LENGTH_2K	2048
 #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_MAC_COUNT		2
 #define MTK_RX_ETH_HLEN		(VLAN_ETH_HLEN + ETH_FCS_LEN)