Sorry, I forgot to mention that I tested this patch on three different
chip versions, RTL_GIGA_MAC_VER_23, RTL_GIGA_MAC_VER_33 and
RTL_GIGA_MAC_VER_35.  I couldn't test on pre-RTL_GIGA_MAC_VER_19, but
the offset handling without counter reset already worked as expected on
later chip versions, so I'm pretty confident that older chip versions
should work accordingly.

On Aug 21 12:09, Corinna Vinschen wrote:
> The r8169 driver collects statistical information returned by
> @get_stats64 by counting them in the driver itself, even though many
> (but not all) of the values are already collected by tally counters
> (TCs) in the NIC.  Some of these TC values are not returned by
> @get_stats64.  Especially the received multicast packages are missing
> from /proc/net/dev.
> 
> Rectify this by fetching the TCs and returning them from
> rtl8169_get_stats64.
> 
> The counters collected in the driver obviously disappear as soon as the
> driver is unloaded so after a driver is loaded the counters always start
> at 0. The TCs on the other hand are only reset by a power cycle.  Without
> further considerations the values collected by the driver would not match
> up against the TC values.
> 
> This patch introduces a new function rtl8169_reset_counters which
> resets the TCs.
> 
> Unfortunately chip versions prior to RTL_GIGA_MAC_VER_19 don't allow
> to reset the TCs programatically.  Therefore introduce an addition to
> the rtl8169_private struct and a function rtl8169_init_counter_offsets
> to store the TCs at first rtl_open.  Use these values as offsets in
> rtl8169_get_stats64.
> 
> Signed-off-by: Corinna Vinschen <vinsc...@redhat.com>
> ---
>  drivers/net/ethernet/realtek/r8169.c | 107 
> +++++++++++++++++++++++++++++++++++
>  1 file changed, 107 insertions(+)
> 
> diff --git a/drivers/net/ethernet/realtek/r8169.c 
> b/drivers/net/ethernet/realtek/r8169.c
> index f790f61..f26a48d 100644
> --- a/drivers/net/ethernet/realtek/r8169.c
> +++ b/drivers/net/ethernet/realtek/r8169.c
> @@ -637,6 +637,9 @@ enum rtl_register_content {
>       /* _TBICSRBit */
>       TBILinkOK       = 0x02000000,
>  
> +     /* ResetCounterCommand */
> +     CounterReset    = 0x1,
> +
>       /* DumpCounterCommand */
>       CounterDump     = 0x8,
>  
> @@ -747,6 +750,14 @@ struct rtl8169_counters {
>       __le16  tx_underun;
>  };
>  
> +struct rtl8169_tc_offsets {
> +     bool    inited;
> +     __le64  tx_errors;
> +     __le32  tx_multi_collision;
> +     __le32  rx_multicast;
> +     __le16  tx_aborted;
> +};
> +
>  enum rtl_flag {
>       RTL_FLAG_TASK_ENABLED,
>       RTL_FLAG_TASK_SLOW_PENDING,
> @@ -824,6 +835,7 @@ struct rtl8169_private {
>  
>       struct mii_if_info mii;
>       struct rtl8169_counters counters;
> +     struct rtl8169_tc_offsets tc_offset;
>       u32 saved_wolopts;
>       u32 opts1_mask;
>  
> @@ -2179,6 +2191,47 @@ static int rtl8169_get_sset_count(struct net_device 
> *dev, int sset)
>       }
>  }
>  
> +DECLARE_RTL_COND(rtl_reset_counters_cond)
> +{
> +     void __iomem *ioaddr = tp->mmio_addr;
> +
> +     return RTL_R32(CounterAddrLow) & CounterReset;
> +}
> +
> +static void rtl8169_reset_counters(struct net_device *dev)
> +{
> +     struct rtl8169_private *tp = netdev_priv(dev);
> +     void __iomem *ioaddr = tp->mmio_addr;
> +     struct device *d = &tp->pci_dev->dev;
> +     struct rtl8169_counters *counters;
> +     dma_addr_t paddr;
> +     u32 cmd;
> +
> +     /*
> +      * Versions prior to RTL_GIGA_MAC_VER_19 don't support resetting the
> +      * tally counters.
> +      */
> +     if (tp->mac_version < RTL_GIGA_MAC_VER_19)
> +             return;
> +
> +     counters = dma_alloc_coherent(d, sizeof(*counters), &paddr, GFP_KERNEL);
> +     if (!counters)
> +             return;
> +
> +     RTL_W32(CounterAddrHigh, (u64)paddr >> 32);
> +     cmd = (u64)paddr & DMA_BIT_MASK(32);
> +     RTL_W32(CounterAddrLow, cmd);
> +     RTL_W32(CounterAddrLow, cmd | CounterReset);
> +
> +     if (!rtl_udelay_loop_wait_low(tp, &rtl_reset_counters_cond, 10, 1000))
> +             netif_warn(tp, hw, dev, "counter reset failed\n");
> +
> +     RTL_W32(CounterAddrLow, 0);
> +     RTL_W32(CounterAddrHigh, 0);
> +
> +     dma_free_coherent(d, sizeof(*counters), counters, paddr);
> +}
> +
>  DECLARE_RTL_COND(rtl_counters_cond)
>  {
>       void __iomem *ioaddr = tp->mmio_addr;
> @@ -2220,6 +2273,39 @@ static void rtl8169_update_counters(struct net_device 
> *dev)
>       dma_free_coherent(d, sizeof(*counters), counters, paddr);
>  }
>  
> +static void rtl8169_init_counter_offsets(struct net_device *dev)
> +{
> +     struct rtl8169_private *tp = netdev_priv(dev);
> +
> +     /*
> +      * rtl8169_init_counter_offsets is called from rtl_open.  On chip
> +      * versions prior to RTL_GIGA_MAC_VER_19 the tally counters are only
> +      * reset by a power cycle, while the counter values collected by the
> +      * driver are reset at every driver unload/load cycle.
> +      *
> +      * To make sure the HW values returned by @get_stats64 match the SW
> +      * values, we collect the initial values at first open(*) and use them
> +      * as offsets to normalize the values returned by @get_stats64.
> +      *
> +      * (*) We can't call rtl8169_init_counter_offsets from rtl_init_one
> +      * for the reason stated in rtl8169_update_counters; CmdRxEnb is only
> +      * set at open time by rtl_hw_start.
> +      */
> +
> +     if (tp->tc_offset.inited)
> +             return;
> +
> +     rtl8169_reset_counters(dev);
> +
> +     rtl8169_update_counters(dev);
> +
> +     tp->tc_offset.tx_errors = tp->counters.tx_errors;
> +     tp->tc_offset.tx_multi_collision = tp->counters.tx_multi_collision;
> +     tp->tc_offset.rx_multicast = tp->counters.rx_multicast;
> +     tp->tc_offset.tx_aborted = tp->counters.tx_aborted;
> +     tp->tc_offset.inited = true;
> +}
> +
>  static void rtl8169_get_ethtool_stats(struct net_device *dev,
>                                     struct ethtool_stats *stats, u64 *data)
>  {
> @@ -7631,6 +7717,8 @@ static int rtl_open(struct net_device *dev)
>  
>       rtl_hw_start(dev);
>  
> +     rtl8169_init_counter_offsets(dev);
> +
>       netif_start_queue(dev);
>  
>       rtl_unlock_work(tp);
> @@ -7689,6 +7777,25 @@ rtl8169_get_stats64(struct net_device *dev, struct 
> rtnl_link_stats64 *stats)
>       stats->rx_fifo_errors   = dev->stats.rx_fifo_errors;
>       stats->rx_missed_errors = dev->stats.rx_missed_errors;
>  
> +     /*
> +      * Fetch additonal counter values missing in stats collected by driver
> +      * from tally counters.
> +      */
> +     rtl8169_update_counters(dev);
> +
> +     /*
> +      * Subtract values fetched during initalization.
> +      * See rtl8169_init_counter_offsets for a description why we do that.
> +      */
> +     stats->tx_errors = le64_to_cpu(tp->counters.tx_errors) -
> +             le64_to_cpu(tp->tc_offset.tx_errors);
> +     stats->collisions = le32_to_cpu(tp->counters.tx_multi_collision) -
> +             le32_to_cpu(tp->tc_offset.tx_multi_collision);
> +     stats->multicast = le32_to_cpu(tp->counters.rx_multicast) -
> +             le32_to_cpu(tp->tc_offset.rx_multicast);
> +     stats->tx_aborted_errors = le16_to_cpu(tp->counters.tx_aborted) -
> +             le16_to_cpu(tp->tc_offset.tx_aborted);
> +
>       return stats;
>  }
>  
> -- 
> 2.1.0
> 
> --
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