net/ps3: Fix gelic RX DMA restart

Fix the condition where PS3 network RX hangs when no network
TX is occurring by calling gelic_card_enable_rxdmac() during
RX_DMA_CHAIN_END event processing.

The gelic hardware automatically clears its RX_DMA_EN flag when
it detects an RX_DMA_CHAIN_END event.  In its processing of
RX_DMA_CHAIN_END the gelic driver is required to set RX_DMA_EN
(with a call to gelic_card_enable_rxdmac()) to restart RX DMA
transfers.  The existing gelic driver code does not set
RX_DMA_EN directly in its processing of the RX_DMA_CHAIN_END
event, but uses a flag variable card->rx_dma_restart_required
to schedule the setting of RX_DMA_EN until next inside the
interrupt handler.

It seems this delayed setting of RX_DMA_EN causes the hang since
the next RX interrupt after the RX_DMA_CHAIN_END event where
RX_DMA_EN is scheduled to be set will not occur since RX_DMA_EN
was not set.  In the case were network TX is occuring, RX_DMA_EN
is set in the next TX interrupt and RX processing continues.

Signed-off-by: Geoff Levand <geoff@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 13 deletions

diff --git a/drivers/net/ps3_gelic_net.c b/drivers/net/ps3_gelic_net.c
index 4acc17bffc42..d82a82d9870c 100644
--- a/drivers/net/ps3_gelic_net.c
+++ b/drivers/net/ps3_gelic_net.c
@@ -993,10 +993,6 @@ static int gelic_card_decode_one_descr(struct gelic_card *card)
         int dmac_chain_ended;
 
         status = gelic_descr_get_status(descr);
-        /* is this descriptor terminated with next_descr == NULL? */
-        dmac_chain_ended =
-                be32_to_cpu(descr->dmac_cmd_status) &
-                GELIC_DESCR_RX_DMA_CHAIN_END;
 
         if (status == GELIC_DESCR_DMA_CARDOWNED)
                 return 0;
@@ -1059,6 +1055,11 @@ static int gelic_card_decode_one_descr(struct gelic_card *card)
         /* ok, we've got a packet in descr */
         gelic_net_pass_skb_up(descr, card, netdev);
 refill:
+
+        /* is the current descriptor terminated with next_descr == NULL? */
+        dmac_chain_ended =
+                be32_to_cpu(descr->dmac_cmd_status) &
+                GELIC_DESCR_RX_DMA_CHAIN_END;
         /*
          * So that always DMAC can see the end
          * of the descriptor chain to avoid
@@ -1087,10 +1088,9 @@ refill:
          * If dmac chain was met, DMAC stopped.
          * thus re-enable it
          */
-        if (dmac_chain_ended) {
-                card->rx_dma_restart_required = 1;
-                dev_dbg(ctodev(card), "reenable rx dma scheduled\n");
-        }
+
+        if (dmac_chain_ended)
+                gelic_card_enable_rxdmac(card);
 
         return 1;
 }
@@ -1156,11 +1156,6 @@ static irqreturn_t gelic_card_interrupt(int irq, void *ptr)
 
         status &= card->irq_mask;
 
-        if (card->rx_dma_restart_required) {
-                card->rx_dma_restart_required = 0;
-                gelic_card_enable_rxdmac(card);
-        }
-
         if (status & GELIC_CARD_RXINT) {
                 gelic_card_rx_irq_off(card);
                 napi_schedule(&card->napi);