openwrt/target/linux/mediatek/patches-4.9/0027-net-next-mediatek-fix-DQL-support.patch

From f974e397b806f7b16d11cc1542538616291924f1 Mon Sep 17 00:00:00 2001
From: John Crispin <john@phrozen.org>
Date: Sat, 23 Apr 2016 11:57:21 +0200
Subject: [PATCH 27/57] net-next: mediatek: fix DQL support

The MTK ethernet core has 2 MACs both sitting on the same DMA ring. The
current code will assign the TX traffic of each MAC to its own DQL. This
results in the amount of data, that DQL says is in the queue incorrect. As
the data from multiple devices is infact enqueued. This makes any decision
based on these value non deterministic. Fix this by tracking all TX
traffic, regardless of the MAC it belongs to in the DQL of all devices
using the DMA.

Signed-off-by: John Crispin <john@phrozen.org>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 35 +++++++++++++++++------------
 1 file changed, 21 insertions(+), 14 deletions(-)

--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -710,7 +710,16 @@ static int mtk_tx_map(struct sk_buff *sk
 	WRITE_ONCE(itxd->txd3, (TX_DMA_SWC | TX_DMA_PLEN0(skb_headlen(skb)) |
 				(!nr_frags * TX_DMA_LS0)));
 
-	netdev_sent_queue(dev, skb->len);
+	/* we have a single DMA ring so BQL needs to be updated for all devices
+	 * sitting on this ring
+	 */
+	for (i = 0; i < MTK_MAC_COUNT; i++) {
+		if (!eth->netdev[i])
+			continue;
+
+		netdev_sent_queue(eth->netdev[i], skb->len);
+	}
+
 	skb_tx_timestamp(skb);
 
 	ring->next_free = mtk_qdma_phys_to_virt(ring, txd->txd2);
@@ -1002,21 +1011,18 @@ static int mtk_poll_tx(struct mtk_eth *e
 	struct mtk_tx_dma *desc;
 	struct sk_buff *skb;
 	struct mtk_tx_buf *tx_buf;
-	unsigned int done[MTK_MAX_DEVS];
-	unsigned int bytes[MTK_MAX_DEVS];
+	int total = 0, done = 0;
+	unsigned int bytes = 0;
 	u32 cpu, dma;
 	static int condition;
-	int total = 0, i;
-
-	memset(done, 0, sizeof(done));
-	memset(bytes, 0, sizeof(bytes));
+	int i;
 
 	cpu = mtk_r32(eth, MTK_QTX_CRX_PTR);
 	dma = mtk_r32(eth, MTK_QTX_DRX_PTR);
 
 	desc = mtk_qdma_phys_to_virt(ring, cpu);
 
-	while ((cpu != dma) && budget) {
+	while ((cpu != dma) && done < budget) {
 		u32 next_cpu = desc->txd2;
 		int mac = 0;
 
@@ -1035,9 +1041,8 @@ static int mtk_poll_tx(struct mtk_eth *e
 		}
 
 		if (skb != (struct sk_buff *)MTK_DMA_DUMMY_DESC) {
-			bytes[mac] += skb->len;
-			done[mac]++;
-			budget--;
+			bytes += skb->len;
+			done++;
 		}
 		mtk_tx_unmap(eth, tx_buf);
 
@@ -1049,11 +1054,13 @@ static int mtk_poll_tx(struct mtk_eth *e
 
 	mtk_w32(eth, cpu, MTK_QTX_CRX_PTR);
 
+	/* we have a single DMA ring so BQL needs to be updated for all devices
+	 * sitting on this ring
+	 */
 	for (i = 0; i < MTK_MAC_COUNT; i++) {
-		if (!eth->netdev[i] || !done[i])
+		if (!eth->netdev[i])
 			continue;
-		netdev_completed_queue(eth->netdev[i], done[i], bytes[i]);
-		total += done[i];
+		netdev_completed_queue(eth->netdev[i], done, bytes);
 	}
 
 	if (mtk_queue_stopped(eth) &&