From: Kazuya Mizuguchi <kazuya.mizuguchi...@renesas.com>

"swiotlb buffer is full" errors occur after repeated initialisation of a
device - f.e. suspend/resume or ip link set up/down. This is because memory
mapped using dma_map_single() in ravb_ring_format() and ravb_start_xmit()
is not released.  Resolve this problem by unmapping descriptors when
freeing rings.

Note, ravb_tx_free() is moved but not otherwise modified by this patch.

Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi...@renesas.com>
[simon: reworked]
Signed-off-by: Simon Horman <horms+rene...@verge.net.au>
--
v1 [Kazuya Mizuguchi]

v2 [Simon Horman]
* As suggested by Sergei Shtylyov
  - Use dma_mapping_error() and rx_desc->ds_cc when unmapping RX descriptors;
    this is consistent with the way that they are mapped
  - Use ravb_tx_free() to clear TX descriptors
* Reduce scope of new local variable
---
 drivers/net/ethernet/renesas/ravb_main.c | 89 ++++++++++++++++++--------------
 1 file changed, 51 insertions(+), 38 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c 
b/drivers/net/ethernet/renesas/ravb_main.c
index 92d7692c840d..1797c48e3176 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -179,6 +179,44 @@ static struct mdiobb_ops bb_ops = {
        .get_mdio_data = ravb_get_mdio_data,
 };
 
+/* Free TX skb function for AVB-IP */
+static int ravb_tx_free(struct net_device *ndev, int q)
+{
+       struct ravb_private *priv = netdev_priv(ndev);
+       struct net_device_stats *stats = &priv->stats[q];
+       struct ravb_tx_desc *desc;
+       int free_num = 0;
+       int entry;
+       u32 size;
+
+       for (; priv->cur_tx[q] - priv->dirty_tx[q] > 0; priv->dirty_tx[q]++) {
+               entry = priv->dirty_tx[q] % (priv->num_tx_ring[q] *
+                                            NUM_TX_DESC);
+               desc = &priv->tx_ring[q][entry];
+               if (desc->die_dt != DT_FEMPTY)
+                       break;
+               /* Descriptor type must be checked before all other reads */
+               dma_rmb();
+               size = le16_to_cpu(desc->ds_tagl) & TX_DS;
+               /* Free the original skb. */
+               if (priv->tx_skb[q][entry / NUM_TX_DESC]) {
+                       dma_unmap_single(ndev->dev.parent, 
le32_to_cpu(desc->dptr),
+                                        size, DMA_TO_DEVICE);
+                       /* Last packet descriptor? */
+                       if (entry % NUM_TX_DESC == NUM_TX_DESC - 1) {
+                               entry /= NUM_TX_DESC;
+                               dev_kfree_skb_any(priv->tx_skb[q][entry]);
+                               priv->tx_skb[q][entry] = NULL;
+                               stats->tx_packets++;
+                       }
+                       free_num++;
+               }
+               stats->tx_bytes += size;
+               desc->die_dt = DT_EEMPTY;
+       }
+       return free_num;
+}
+
 /* Free skb's and DMA buffers for Ethernet AVB */
 static void ravb_ring_free(struct net_device *ndev, int q)
 {
@@ -207,6 +245,18 @@ static void ravb_ring_free(struct net_device *ndev, int q)
        priv->tx_align[q] = NULL;
 
        if (priv->rx_ring[q]) {
+               for (i = 0; i < priv->num_rx_ring[q]; i++) {
+                       struct ravb_ex_rx_desc *rx_desc = &priv->rx_ring[q][i];
+
+                       if (!dma_mapping_error(ndev->dev.parent,
+                                              rx_desc->dptr)) {
+                               dma_unmap_single(ndev->dev.parent,
+                                                le32_to_cpu(rx_desc->dptr),
+                                                PKT_BUF_SZ,
+                                                DMA_FROM_DEVICE);
+                               rx_desc->ds_cc = cpu_to_le16(0);
+                       }
+               }
                ring_size = sizeof(struct ravb_ex_rx_desc) *
                            (priv->num_rx_ring[q] + 1);
                dma_free_coherent(ndev->dev.parent, ring_size, priv->rx_ring[q],
@@ -215,6 +265,7 @@ static void ravb_ring_free(struct net_device *ndev, int q)
        }
 
        if (priv->tx_ring[q]) {
+               ravb_tx_free(ndev, q);
                ring_size = sizeof(struct ravb_tx_desc) *
                            (priv->num_tx_ring[q] * NUM_TX_DESC + 1);
                dma_free_coherent(ndev->dev.parent, ring_size, priv->tx_ring[q],
@@ -431,44 +482,6 @@ static int ravb_dmac_init(struct net_device *ndev)
        return 0;
 }
 
-/* Free TX skb function for AVB-IP */
-static int ravb_tx_free(struct net_device *ndev, int q)
-{
-       struct ravb_private *priv = netdev_priv(ndev);
-       struct net_device_stats *stats = &priv->stats[q];
-       struct ravb_tx_desc *desc;
-       int free_num = 0;
-       int entry;
-       u32 size;
-
-       for (; priv->cur_tx[q] - priv->dirty_tx[q] > 0; priv->dirty_tx[q]++) {
-               entry = priv->dirty_tx[q] % (priv->num_tx_ring[q] *
-                                            NUM_TX_DESC);
-               desc = &priv->tx_ring[q][entry];
-               if (desc->die_dt != DT_FEMPTY)
-                       break;
-               /* Descriptor type must be checked before all other reads */
-               dma_rmb();
-               size = le16_to_cpu(desc->ds_tagl) & TX_DS;
-               /* Free the original skb. */
-               if (priv->tx_skb[q][entry / NUM_TX_DESC]) {
-                       dma_unmap_single(ndev->dev.parent, 
le32_to_cpu(desc->dptr),
-                                        size, DMA_TO_DEVICE);
-                       /* Last packet descriptor? */
-                       if (entry % NUM_TX_DESC == NUM_TX_DESC - 1) {
-                               entry /= NUM_TX_DESC;
-                               dev_kfree_skb_any(priv->tx_skb[q][entry]);
-                               priv->tx_skb[q][entry] = NULL;
-                               stats->tx_packets++;
-                       }
-                       free_num++;
-               }
-               stats->tx_bytes += size;
-               desc->die_dt = DT_EEMPTY;
-       }
-       return free_num;
-}
-
 static void ravb_get_tx_tstamp(struct net_device *ndev)
 {
        struct ravb_private *priv = netdev_priv(ndev);
-- 
2.7.0.rc3.207.g0ac5344

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