[TG3]: Add rx BD workaround

Add workaround to limit the burst size of rx BDs being DMA'ed to the
chip.  This works around hardware errata on a number of 5750, 5752,
and 5755 chips.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 29 insertions, 2 deletions

diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index 2447fa3b471b..c32655ca3c46 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -3195,7 +3195,7 @@ static int tg3_vlan_rx(struct tg3 *tp, struct sk_buff *skb, u16 vlan_tag)
  */
 static int tg3_rx(struct tg3 *tp, int budget)
 {
-        u32 work_mask;
+        u32 work_mask, rx_std_posted = 0;
         u32 sw_idx = tp->rx_rcb_ptr;
         u16 hw_idx;
         int received;
@@ -3222,6 +3222,7 @@ static int tg3_rx(struct tg3 *tp, int budget)
                                                   mapping);
                         skb = tp->rx_std_buffers[desc_idx].skb;
                         post_ptr = &tp->rx_std_ptr;
+                        rx_std_posted++;
                 } else if (opaque_key == RXD_OPAQUE_RING_JUMBO) {
                         dma_addr = pci_unmap_addr(&tp->rx_jumbo_buffers[desc_idx],
                                                   mapping);
@@ -3309,6 +3310,15 @@ static int tg3_rx(struct tg3 *tp, int budget)
 
 next_pkt:
                 (*post_ptr)++;
+
+                if (unlikely(rx_std_posted >= tp->rx_std_max_post)) {
+                        u32 idx = *post_ptr % TG3_RX_RING_SIZE;
+
+                        tw32_rx_mbox(MAILBOX_RCV_STD_PROD_IDX +
+                                     TG3_64BIT_REG_LOW, idx);
+                        work_mask &= ~RXD_OPAQUE_RING_STD;
+                        rx_std_posted = 0;
+                }
 next_pkt_nopost:
                 sw_idx++;
                 sw_idx %= TG3_RX_RCB_RING_SIZE(tp);
@@ -5981,7 +5991,13 @@ static int tg3_reset_hw(struct tg3 *tp, int reset_phy)
         }
 
         /* Setup replenish threshold. */
-        tw32(RCVBDI_STD_THRESH, tp->rx_pending / 8);
+        val = tp->rx_pending / 8;
+        if (val == 0)
+                val = 1;
+        else if (val > tp->rx_std_max_post)
+                val = tp->rx_std_max_post;
+
+        tw32(RCVBDI_STD_THRESH, val);
 
         /* Initialize TG3_BDINFO's at:
          *  RCVDBDI_STD_BD:     standard eth size rx ring
@@ -10545,6 +10561,16 @@ static int __devinit tg3_get_invariants(struct tg3 *tp)
             (tp->tg3_flags & TG3_FLAG_PCIX_MODE) != 0)
                 tp->rx_offset = 0;
 
+        tp->rx_std_max_post = TG3_RX_RING_SIZE;
+
+        /* Increment the rx prod index on the rx std ring by at most
+         * 8 for these chips to workaround hw errata.
+         */
+        if (GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5750 ||
+            GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5752 ||
+            GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5755)
+                tp->rx_std_max_post = 8;
+
         /* By default, disable wake-on-lan.  User can change this
          * using ETHTOOL_SWOL.
          */
diff --git a/drivers/net/tg3.h b/drivers/net/tg3.h
index 8209da5dd15f..e9177f8521df 100644
--- a/drivers/net/tg3.h
+++ b/drivers/net/tg3.h
@@ -2137,6 +2137,7 @@ struct tg3 {
         struct tg3_rx_buffer_desc       *rx_std;
         struct ring_info                *rx_std_buffers;
         dma_addr_t                      rx_std_mapping;
+        u32                             rx_std_max_post;
 
         struct tg3_rx_buffer_desc       *rx_jumbo;
         struct ring_info                *rx_jumbo_buffers;