net: bcmgenet: collect Rx discarded packet count

Bits 31:16 of RDMA_PROD_INDEX contain Rx discarded packet count, which
are the Rx packets that had to be dropped by MAC hardware since there
was no room on the Rx queue. Add code to collect this information into
the netdev stats.

Signed-off-by: Petri Gynther <pgynther@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
index 275be56fd324c38ab7b75e64c3ce0e62e541a0a7..d3be1aeb7f47130a35cc86e32a36c7ccd70cfa8d 100644 (file)
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
@@ -1384,9 +1384,27 @@ static unsigned int bcmgenet_desc_rx(struct bcmgenet_priv *priv,
        int len, err;
        unsigned int rxpktprocessed = 0, rxpkttoprocess;
        unsigned int p_index;
+       unsigned int discards;
        unsigned int chksum_ok = 0;
 
        p_index = bcmgenet_rdma_ring_readl(priv, index, RDMA_PROD_INDEX);
+
+       discards = (p_index >> DMA_P_INDEX_DISCARD_CNT_SHIFT) &
+                  DMA_P_INDEX_DISCARD_CNT_MASK;
+       if (discards > ring->old_discards) {
+               discards = discards - ring->old_discards;
+               dev->stats.rx_missed_errors += discards;
+               dev->stats.rx_errors += discards;
+               ring->old_discards += discards;
+
+               /* Clear HW register when we reach 75% of maximum 0xFFFF */
+               if (ring->old_discards >= 0xC000) {
+                       ring->old_discards = 0;
+                       bcmgenet_rdma_ring_writel(priv, index, 0,
+                                                 RDMA_PROD_INDEX);
+               }
+       }
+
        p_index &= DMA_P_INDEX_MASK;
 
        if (likely(p_index >= ring->c_index))

diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.h b/drivers/net/ethernet/broadcom/genet/bcmgenet.h
index 17443db8dc53bb06e203652168b3706370112546..2a8113898aed950be16767a5933de83a8c052a1c 100644 (file)
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.h
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.h
@@ -548,6 +548,7 @@ struct bcmgenet_rx_ring {
        unsigned int    read_ptr;       /* Rx ring read pointer */
        unsigned int    cb_ptr;         /* Rx ring initial CB ptr */
        unsigned int    end_ptr;        /* Rx ring end CB ptr */
+       unsigned int    old_discards;
 };
 
 /* device context */