[TG3]: Prescaler fix

Internal hardware timers become inaccurate after link events.  Clock
frequency switches performed by the CPMU fail to adjust timer
prescalers.  The fix is to detect core clock frequency changes during
link events and adjust the timer prescalers accordingly.

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

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/net/tg3.c b/drivers/net/tg3.c
index bb3b73435170..ecd64a224e95 100644
--- a/drivers/net/tg3.c
+++ b/drivers/net/tg3.c
@@ -3154,6 +3154,22 @@ static int tg3_setup_phy(struct tg3 *tp, int force_reset)
                 err = tg3_setup_copper_phy(tp, force_reset);
         }
 
+        if (tp->pci_chip_rev_id == CHIPREV_ID_5784_A0) {
+                u32 val, scale;
+
+                val = tr32(TG3_CPMU_CLCK_STAT) & CPMU_CLCK_STAT_MAC_CLCK_MASK;
+                if (val == CPMU_CLCK_STAT_MAC_CLCK_62_5)
+                        scale = 65;
+                else if (val == CPMU_CLCK_STAT_MAC_CLCK_6_25)
+                        scale = 6;
+                else
+                        scale = 12;
+
+                val = tr32(GRC_MISC_CFG) & ~GRC_MISC_CFG_PRESCALAR_MASK;
+                val |= (scale << GRC_MISC_CFG_PRESCALAR_SHIFT);
+                tw32(GRC_MISC_CFG, val);
+        }
+
         if (tp->link_config.active_speed == SPEED_1000 &&
             tp->link_config.active_duplex == DUPLEX_HALF)
                 tw32(MAC_TX_LENGTHS,