From 5ed83c47b4d4cbb4a42065613a2df465221b86d8 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Fri, 13 Mar 2015 06:50:13 +0100
Subject: [PATCH] dma: do not check the DMA_DONE bit for tx, use the dma index
 register instead

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
 dma.c | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/dma.c b/dma.c
index c1289a52..84052e02 100644
--- a/dma.c
+++ b/dma.c
@@ -20,6 +20,12 @@ struct mt76_txwi_cache {
 	struct list_head list;
 };
 
+enum mt76_dma_dequeue {
+	DMA_DEQUEUE_FLUSH,
+	DMA_DEQUEUE_DDONE,
+	DMA_DEQUEUE_IDX,
+};
+
 static inline int
 mt76_rx_buf_offset(struct mt76_dev *dev)
 {
@@ -261,16 +267,31 @@ free:
 }
 
 static int
-mt76_dma_dequeue(struct mt76_dev *dev, struct mt76_queue *q, bool flush)
+mt76_dma_dequeue(struct mt76_dev *dev, struct mt76_queue *q, enum mt76_dma_dequeue type)
 {
 	int ret = -1;
+	u16 idx;
+	bool skip;
 
 	spin_lock_bh(&q->lock);
 
 	if (!q->queued)
 		goto out;
 
-	if (!flush && !(q->desc[q->tail].ctrl & cpu_to_le32(MT_DMA_CTL_DMA_DONE)))
+	switch (type) {
+	case DMA_DEQUEUE_DDONE:
+		skip = !(q->desc[q->tail].ctrl & cpu_to_le32(MT_DMA_CTL_DMA_DONE));
+		break;
+	case DMA_DEQUEUE_IDX:
+		idx = ioread32(&q->regs->dma_idx);
+		skip = (q->tail == idx);
+		break;
+	case DMA_DEQUEUE_FLUSH:
+		skip = false;
+		break;
+	}
+
+	if (skip)
 		goto out;
 
 	ret = q->tail;
@@ -321,10 +342,11 @@ mt76_tx_cleanup_entry(struct mt76_dev *dev, struct mt76_queue *q, int idx,
 static void
 mt76_tx_cleanup_queue(struct mt76_dev *dev, struct mt76_queue *q, bool flush)
 {
+	enum mt76_dma_dequeue type = flush ? DMA_DEQUEUE_FLUSH : DMA_DEQUEUE_IDX;
 	int idx;
 
 	do {
-		idx = mt76_dma_dequeue(dev, q, flush);
+		idx = mt76_dma_dequeue(dev, q, type);
 		if (idx < 0)
 			break;
 
@@ -359,7 +381,7 @@ mt76_rx_cleanup(struct mt76_dev *dev, struct mt76_queue *q)
 	int idx;
 
 	do {
-		idx = mt76_dma_dequeue(dev, q, true);
+		idx = mt76_dma_dequeue(dev, q, DMA_DEQUEUE_FLUSH);
 		if (idx < 0)
 			break;
 
@@ -425,7 +447,7 @@ mt76_process_rx_queue(struct mt76_dev *dev, struct mt76_queue *q, int budget)
 	int done = 0;
 
 	while (done < budget) {
-		idx = mt76_dma_dequeue(dev, q, false);
+		idx = mt76_dma_dequeue(dev, q, DMA_DEQUEUE_DDONE);
 		if (idx < 0)
 			break;