ravb: TROCR register is only present on R-Car Gen3

Only use the TROCR register on R-Car Gen3 as it is not present on other
SoCs.

Offsets used for the undocumented registers are considered reserved and
should not be written to. After some internal investigation with Renesas it
remains unclear why this driver accesses these fields on R-Car Gen2 but
regardless of what the historical reasons are the current code is
considered incorrect.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Acked-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
index bdb051f..a9c89d5 100644 (file)
--- a/drivers/net/ethernet/renesas/ravb.h
+++ b/drivers/net/ethernet/renesas/ravb.h
@@ -193,7 +193,7 @@ enum ravb_reg {
        GECMR   = 0x05b0,
        MAHR    = 0x05c0,
        MALR    = 0x05c8,
-       TROCR   = 0x0700,       /* Undocumented? */
+       TROCR   = 0x0700,       /* R-Car Gen3 only */
        CEFCR   = 0x0740,
        FRECR   = 0x0748,
        TSFRCR  = 0x0750,

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index b538cc6..de9aa8c 100644 (file)
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -1621,8 +1621,10 @@ static struct net_device_stats *ravb_get_stats(struct net_device *ndev)
        stats0 = &priv->stats[RAVB_BE];
        stats1 = &priv->stats[RAVB_NC];
 
-       nstats->tx_dropped += ravb_read(ndev, TROCR);
-       ravb_write(ndev, 0, TROCR);     /* (write clear) */
+       if (priv->chip_id == RCAR_GEN3) {
+               nstats->tx_dropped += ravb_read(ndev, TROCR);
+               ravb_write(ndev, 0, TROCR);     /* (write clear) */
+       }
 
        nstats->rx_packets = stats0->rx_packets + stats1->rx_packets;
        nstats->tx_packets = stats0->tx_packets + stats1->tx_packets;