4 files changed, 57 insertions, 13 deletions

diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
index 3772804fb697..b35e6a76664c 100644
--- a/drivers/net/ethernet/ti/cpsw.c
+++ b/drivers/net/ethernet/ti/cpsw.c
@@ -374,6 +374,9 @@ void cpsw_tx_handler(void *token, int len, int status)
         struct net_device       *ndev = skb->dev;
         struct cpsw_priv        *priv = netdev_priv(ndev);
 
+        /* Check whether the queue is stopped due to stalled tx dma, if the
+         * queue is stopped then start the queue as we have free desc for tx
+         */
         if (unlikely(netif_queue_stopped(ndev)))
                 netif_start_queue(ndev);
         cpts_tx_timestamp(&priv->cpts, skb);
@@ -736,6 +739,12 @@ static netdev_tx_t cpsw_ndo_start_xmit(struct sk_buff *skb,
                 goto fail;
         }
 
+        /* If there is no more tx desc left free then we need to
+         * tell the kernel to stop sending us tx frames.
+         */
+        if (unlikely(cpdma_check_free_tx_desc(priv->txch)))
+                netif_stop_queue(ndev);
+
         return NETDEV_TX_OK;
 fail:
         priv->stats.tx_dropped++;
diff --git a/drivers/net/ethernet/ti/davinci_cpdma.c b/drivers/net/ethernet/ti/davinci_cpdma.c
index 49956730cd8d..f8629186afbe 100644
--- a/drivers/net/ethernet/ti/davinci_cpdma.c
+++ b/drivers/net/ethernet/ti/davinci_cpdma.c
@@ -105,13 +105,13 @@ struct cpdma_ctlr {
 };
 
 struct cpdma_chan {
+        struct cpdma_desc __iomem       *head, *tail;
+        void __iomem                    *hdp, *cp, *rxfree;
         enum cpdma_state                state;
         struct cpdma_ctlr               *ctlr;
         int                             chan_num;
         spinlock_t                      lock;
-        struct cpdma_desc __iomem       *head, *tail;
         int                             count;
-        void __iomem                    *hdp, *cp, *rxfree;
         u32                             mask;
         cpdma_handler_fn                handler;
         enum dma_data_direction         dir;
@@ -217,17 +217,27 @@ desc_from_phys(struct cpdma_desc_pool *pool, dma_addr_t dma)
 }
 
 static struct cpdma_desc __iomem *
-cpdma_desc_alloc(struct cpdma_desc_pool *pool, int num_desc)
+cpdma_desc_alloc(struct cpdma_desc_pool *pool, int num_desc, bool is_rx)
 {
         unsigned long flags;
         int index;
+        int desc_start;
+        int desc_end;
         struct cpdma_desc __iomem *desc = NULL;
 
         spin_lock_irqsave(&pool->lock, flags);
 
-        index = bitmap_find_next_zero_area(pool->bitmap, pool->num_desc, 0,
-                                           num_desc, 0);
-        if (index < pool->num_desc) {
+        if (is_rx) {
+                desc_start = 0;
+                desc_end = pool->num_desc/2;
+         } else {
+                desc_start = pool->num_desc/2;
+                desc_end = pool->num_desc;
+        }
+
+        index = bitmap_find_next_zero_area(pool->bitmap,
+                                desc_end, desc_start, num_desc, 0);
+        if (index < desc_end) {
                 bitmap_set(pool->bitmap, index, num_desc);
                 desc = pool->iomap + pool->desc_size * index;
                 pool->used_desc++;
@@ -668,7 +678,7 @@ int cpdma_chan_submit(struct cpdma_chan *chan, void *token, void *data,
                 goto unlock_ret;
         }
 
-        desc = cpdma_desc_alloc(ctlr->pool, 1);
+        desc = cpdma_desc_alloc(ctlr->pool, 1, is_rx_chan(chan));
         if (!desc) {
                 chan->stats.desc_alloc_fail++;
                 ret = -ENOMEM;
@@ -704,6 +714,29 @@ unlock_ret:
 }
 EXPORT_SYMBOL_GPL(cpdma_chan_submit);
 
+bool cpdma_check_free_tx_desc(struct cpdma_chan *chan)
+{
+        unsigned long flags;
+        int index;
+        bool ret;
+        struct cpdma_ctlr       *ctlr = chan->ctlr;
+        struct cpdma_desc_pool  *pool = ctlr->pool;
+
+        spin_lock_irqsave(&pool->lock, flags);
+
+        index = bitmap_find_next_zero_area(pool->bitmap,
+                                pool->num_desc, pool->num_desc/2, 1, 0);
+
+        if (index < pool->num_desc)
+                ret = true;
+        else
+                ret = false;
+
+        spin_unlock_irqrestore(&pool->lock, flags);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(cpdma_check_free_tx_desc);
+
 static void __cpdma_chan_free(struct cpdma_chan *chan,
                               struct cpdma_desc __iomem *desc,
                               int outlen, int status)
diff --git a/drivers/net/ethernet/ti/davinci_cpdma.h b/drivers/net/ethernet/ti/davinci_cpdma.h
index afa19a0c0d81..8d2aeb2096ac 100644
--- a/drivers/net/ethernet/ti/davinci_cpdma.h
+++ b/drivers/net/ethernet/ti/davinci_cpdma.h
@@ -88,6 +88,7 @@ int cpdma_chan_process(struct cpdma_chan *chan, int quota);
 int cpdma_ctlr_int_ctrl(struct cpdma_ctlr *ctlr, bool enable);
 void cpdma_ctlr_eoi(struct cpdma_ctlr *ctlr);
 int cpdma_chan_int_ctrl(struct cpdma_chan *chan, bool enable);
+bool cpdma_check_free_tx_desc(struct cpdma_chan *chan);
 
 enum cpdma_control {
         CPDMA_CMD_IDLE,                 /* write-only */
diff --git a/drivers/net/ethernet/ti/davinci_emac.c b/drivers/net/ethernet/ti/davinci_emac.c
index 8478d98c1092..1c97c8171d3e 100644
--- a/drivers/net/ethernet/ti/davinci_emac.c
+++ b/drivers/net/ethernet/ti/davinci_emac.c
@@ -120,7 +120,6 @@ static const char emac_version_string[] = "TI DaVinci EMAC Linux v6.1";
 #define EMAC_DEF_TX_CH                  (0) /* Default 0th channel */
 #define EMAC_DEF_RX_CH                  (0) /* Default 0th channel */
 #define EMAC_DEF_RX_NUM_DESC            (128)
-#define EMAC_DEF_TX_NUM_DESC            (128)
 #define EMAC_DEF_MAX_TX_CH              (1) /* Max TX channels configured */
 #define EMAC_DEF_MAX_RX_CH              (1) /* Max RX channels configured */
 #define EMAC_POLL_WEIGHT                (64) /* Default NAPI poll weight */
@@ -342,7 +341,6 @@ struct emac_priv {
         u32 mac_hash2;
         u32 multicast_hash_cnt[EMAC_NUM_MULTICAST_BITS];
         u32 rx_addr_type;
-        atomic_t cur_tx;
         const char *phy_id;
 #ifdef CONFIG_OF
         struct device_node *phy_node;
@@ -1050,10 +1048,10 @@ static void emac_tx_handler(void *token, int len, int status)
 {
         struct sk_buff          *skb = token;
         struct net_device       *ndev = skb->dev;
-        struct emac_priv        *priv = netdev_priv(ndev);
-
-        atomic_dec(&priv->cur_tx);
 
+        /* Check whether the queue is stopped due to stalled tx dma, if the
+         * queue is stopped then start the queue as we have free desc for tx
+         */
         if (unlikely(netif_queue_stopped(ndev)))
                 netif_start_queue(ndev);
         ndev->stats.tx_packets++;
@@ -1101,7 +1099,10 @@ static int emac_dev_xmit(struct sk_buff *skb, struct net_device *ndev)
                 goto fail_tx;
         }
 
-        if (atomic_inc_return(&priv->cur_tx) >= EMAC_DEF_TX_NUM_DESC)
+        /* If there is no more tx desc left free then we need to
+         * tell the kernel to stop sending us tx frames.
+         */
+        if (unlikely(cpdma_check_free_tx_desc(priv->txch)))
                 netif_stop_queue(ndev);
 
         return NETDEV_TX_OK;