tg3: Fix read DMA FIFO overruns on recent devices

Earlier versions of tg3 devices had a problem where the read DMA FIFO
could be overrun in certain edge conditions.  The fix was to limit the
number of rx BDs the hardware would fetch at a time.  For later devices
(5761, 5784 and later ASIC revs), there is a hardware fix that must be
enabled to fix the same problem.  This patch adds that hardware fix.

There is a gap in the ASIC revision lineage where neither fix is
applied.  This is intentional as these ASIC revisions are not afflicted
by the bug.

Reviewed-by: Benjamin Li <benli@broadcom.com>
Reviewed-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 15 insertions, 1 deletions

diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index 9f6ffffc8376..c3a430cfbe00 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -8015,6 +8015,16 @@ static int tg3_reset_hw(struct tg3 *tp, int reset_phy)
             GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_57780)
                 rdmac_mode |= RDMAC_MODE_IPV6_LSO_EN;
 
+        if (GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5761 ||
+            GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5784 ||
+            GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5785 ||
+            GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_57780 ||
+            (tp->tg3_flags3 & TG3_FLG3_5717_PLUS)) {
+                val = tr32(TG3_RDMA_RSRVCTRL_REG);
+                tw32(TG3_RDMA_RSRVCTRL_REG,
+                     val | TG3_RDMA_RSRVCTRL_FIFO_OFLW_FIX);
+        }
+
         /* Receive/send statistics. */
         if (tp->tg3_flags2 & TG3_FLG2_5750_PLUS) {
                 val = tr32(RCVLPC_STATS_ENABLE);
diff --git a/drivers/net/tg3.h b/drivers/net/tg3.h
index 4937bd190964..783cd77b6165 100644
--- a/drivers/net/tg3.h
+++ b/drivers/net/tg3.h
@@ -1302,7 +1302,11 @@
 #define  RDMAC_STATUS_FIFOURUN           0x00000080
 #define  RDMAC_STATUS_FIFOOREAD          0x00000100
 #define  RDMAC_STATUS_LNGREAD            0x00000200
-/* 0x4808 --> 0x4c00 unused */
+/* 0x4808 --> 0x4900 unused */
+
+#define TG3_RDMA_RSRVCTRL_REG           0x00004900
+#define TG3_RDMA_RSRVCTRL_FIFO_OFLW_FIX  0x00000004
+/* 0x4904 --> 0x4c00 unused */
 
 /* Write DMA control registers */
 #define WDMAC_MODE                      0x00004c00