Spidernet: Rework RX linked list

Make the hardware perceive the RX descriptor ring as a null-terminated linked
list, instead of a circular ring.

Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Cc: James K Lewis <jklewis@us.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 4 insertions, 8 deletions

diff --git a/drivers/net/spider_net.c b/drivers/net/spider_net.c
index d73018b5cfc8..bf6ff39e02bb 100644
--- a/drivers/net/spider_net.c
+++ b/drivers/net/spider_net.c
@@ -419,9 +419,13 @@ spider_net_prepare_rx_descr(struct spider_net_card *card,
                 card->spider_stats.rx_iommu_map_error++;
                 descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;
         } else {
+                descr->next_descr_addr = 0;
                 wmb();
                 descr->dmac_cmd_status = SPIDER_NET_DESCR_CARDOWNED |
                                          SPIDER_NET_DMAC_NOINTR_COMPLETE;
+
+                wmb();
+                descr->prev->next_descr_addr = descr->bus_addr;
         }
 
         return 0;
@@ -1650,7 +1654,6 @@ int
 spider_net_open(struct net_device *netdev)
 {
         struct spider_net_card *card = netdev_priv(netdev);
-        struct spider_net_descr *descr;
         int result;
 
         result = spider_net_init_chain(card, &card->tx_chain);
@@ -1662,13 +1665,6 @@ spider_net_open(struct net_device *netdev)
         if (result)
                 goto alloc_rx_failed;
 
-        /* Make a ring of of bus addresses */
-        descr = card->rx_chain.ring;
-        do {
-                descr->next_descr_addr = descr->next->bus_addr;
-                descr = descr->next;
-        } while (descr != card->rx_chain.ring);
-
         /* Allocate rx skbs */
         if (spider_net_alloc_rx_skbs(card))
                 goto alloc_skbs_failed;