i40e: fix for flow director counters not wrapping as expected

An errata with GLQF_PCNT causes it to not wrap as expected. This
can cause an error in flow director statistics. This patch resets
affected counters just after reading.

Signed-off-by: Mariusz Stachura <mariusz.stachura@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index a887087..638f5ba 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -600,6 +600,20 @@ static void i40e_stat_update32(struct i40e_hw *hw, u32 reg,
 }
 
 /**
+ * i40e_stat_update_and_clear32 - read and clear hw reg, update a 32 bit stat
+ * @hw: ptr to the hardware info
+ * @reg: the hw reg to read and clear
+ * @stat: ptr to the stat
+ **/
+static void i40e_stat_update_and_clear32(struct i40e_hw *hw, u32 reg, u64 *stat)
+{
+       u32 new_data = rd32(hw, reg);
+
+       wr32(hw, reg, 1); /* must write a nonzero value to clear register */
+       *stat += new_data;
+}
+
+/**
  * i40e_update_eth_stats - Update VSI-specific ethernet statistics counters.
  * @vsi: the VSI to be updated
  **/
@@ -1040,18 +1054,15 @@ static void i40e_update_pf_stats(struct i40e_pf *pf)
                           &osd->rx_jabber, &nsd->rx_jabber);
 
        /* FDIR stats */
-       i40e_stat_update32(hw,
-                          I40E_GLQF_PCNT(I40E_FD_ATR_STAT_IDX(pf->hw.pf_id)),
-                          pf->stat_offsets_loaded,
-                          &osd->fd_atr_match, &nsd->fd_atr_match);
-       i40e_stat_update32(hw,
-                          I40E_GLQF_PCNT(I40E_FD_SB_STAT_IDX(pf->hw.pf_id)),
-                          pf->stat_offsets_loaded,
-                          &osd->fd_sb_match, &nsd->fd_sb_match);
-       i40e_stat_update32(hw,
-                     I40E_GLQF_PCNT(I40E_FD_ATR_TUNNEL_STAT_IDX(pf->hw.pf_id)),
-                     pf->stat_offsets_loaded,
-                     &osd->fd_atr_tunnel_match, &nsd->fd_atr_tunnel_match);
+       i40e_stat_update_and_clear32(hw,
+                       I40E_GLQF_PCNT(I40E_FD_ATR_STAT_IDX(hw->pf_id)),
+                       &nsd->fd_atr_match);
+       i40e_stat_update_and_clear32(hw,
+                       I40E_GLQF_PCNT(I40E_FD_SB_STAT_IDX(hw->pf_id)),
+                       &nsd->fd_sb_match);
+       i40e_stat_update_and_clear32(hw,
+                       I40E_GLQF_PCNT(I40E_FD_ATR_TUNNEL_STAT_IDX(hw->pf_id)),
+                       &nsd->fd_atr_tunnel_match);
 
        val = rd32(hw, I40E_PRTPM_EEE_STAT);
        nsd->tx_lpi_status =