gianfar: Avoid unnecessary reg accesses in adjust_link()

For phy devices that don't issue interrupts upon link
state changes, phylib polls the link state resulting in
repeated calls to adjust_link(), even if the link state
didn't change.  As a result, some mac registers are
repeatedly read and written with the same values, which
is not ok.

To fix this, adjust_link() has been refactored to check
first whether the link state has changed and to take action
only if needed, updating mac registers and local state
variables.  The 'new_state' local flag, set if one of the
link params changed (link, speed or duplex), has been
rendered useless and removed by this refactoring.

Signed-off-by: Claudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/freescale/gianfar.c b/drivers/net/ethernet/freescale/gianfar.c
index 9125d9a..e2d4247 100644 (file)
--- a/drivers/net/ethernet/freescale/gianfar.c
+++ b/drivers/net/ethernet/freescale/gianfar.c
@@ -121,6 +121,7 @@ static irqreturn_t gfar_error(int irq, void *dev_id);
 static irqreturn_t gfar_transmit(int irq, void *dev_id);
 static irqreturn_t gfar_interrupt(int irq, void *dev_id);
 static void adjust_link(struct net_device *dev);
+static noinline void gfar_update_link_state(struct gfar_private *priv);
 static int init_phy(struct net_device *dev);
 static int gfar_probe(struct platform_device *ofdev);
 static int gfar_remove(struct platform_device *ofdev);
@@ -3076,41 +3077,6 @@ static irqreturn_t gfar_interrupt(int irq, void *grp_id)
        return IRQ_HANDLED;
 }
 
-static u32 gfar_get_flowctrl_cfg(struct gfar_private *priv)
-{
-       struct phy_device *phydev = priv->phydev;
-       u32 val = 0;
-
-       if (!phydev->duplex)
-               return val;
-
-       if (!priv->pause_aneg_en) {
-               if (priv->tx_pause_en)
-                       val |= MACCFG1_TX_FLOW;
-               if (priv->rx_pause_en)
-                       val |= MACCFG1_RX_FLOW;
-       } else {
-               u16 lcl_adv, rmt_adv;
-               u8 flowctrl;
-               /* get link partner capabilities */
-               rmt_adv = 0;
-               if (phydev->pause)
-                       rmt_adv = LPA_PAUSE_CAP;
-               if (phydev->asym_pause)
-                       rmt_adv |= LPA_PAUSE_ASYM;
-
-               lcl_adv = mii_advertise_flowctrl(phydev->advertising);
-
-               flowctrl = mii_resolve_flowctrl_fdx(lcl_adv, rmt_adv);
-               if (flowctrl & FLOW_CTRL_TX)
-                       val |= MACCFG1_TX_FLOW;
-               if (flowctrl & FLOW_CTRL_RX)
-                       val |= MACCFG1_RX_FLOW;
-       }
-
-       return val;
-}
-
 /* Called every time the controller might need to be made
  * aware of new link state.  The PHY code conveys this
  * information through variables in the phydev structure, and this
@@ -3120,83 +3086,12 @@ static u32 gfar_get_flowctrl_cfg(struct gfar_private *priv)
 static void adjust_link(struct net_device *dev)
 {
        struct gfar_private *priv = netdev_priv(dev);
-       struct gfar __iomem *regs = priv->gfargrp[0].regs;
        struct phy_device *phydev = priv->phydev;
-       int new_state = 0;
 
-       if (test_bit(GFAR_RESETTING, &priv->state))
-               return;
-
-       if (phydev->link) {
-               u32 tempval1 = gfar_read(&regs->maccfg1);
-               u32 tempval = gfar_read(&regs->maccfg2);
-               u32 ecntrl = gfar_read(&regs->ecntrl);
-
-               /* Now we make sure that we can be in full duplex mode.
-                * If not, we operate in half-duplex mode.
-                */
-               if (phydev->duplex != priv->oldduplex) {
-                       new_state = 1;
-                       if (!(phydev->duplex))
-                               tempval &= ~(MACCFG2_FULL_DUPLEX);
-                       else
-                               tempval |= MACCFG2_FULL_DUPLEX;
-
-                       priv->oldduplex = phydev->duplex;
-               }
-
-               if (phydev->speed != priv->oldspeed) {
-                       new_state = 1;
-                       switch (phydev->speed) {
-                       case 1000:
-                               tempval =
-                                   ((tempval & ~(MACCFG2_IF)) | MACCFG2_GMII);
-
-                               ecntrl &= ~(ECNTRL_R100);
-                               break;
-                       case 100:
-                       case 10:
-                               tempval =
-                                   ((tempval & ~(MACCFG2_IF)) | MACCFG2_MII);
-
-                               /* Reduced mode distinguishes
-                                * between 10 and 100
-                                */
-                               if (phydev->speed == SPEED_100)
-                                       ecntrl |= ECNTRL_R100;
-                               else
-                                       ecntrl &= ~(ECNTRL_R100);
-                               break;
-                       default:
-                               netif_warn(priv, link, dev,
-                                          "Ack!  Speed (%d) is not 10/100/1000!\n",
-                                          phydev->speed);
-                               break;
-                       }
-
-                       priv->oldspeed = phydev->speed;
-               }
-
-               tempval1 &= ~(MACCFG1_TX_FLOW | MACCFG1_RX_FLOW);
-               tempval1 |= gfar_get_flowctrl_cfg(priv);
-
-               gfar_write(&regs->maccfg1, tempval1);
-               gfar_write(&regs->maccfg2, tempval);
-               gfar_write(&regs->ecntrl, ecntrl);
-
-               if (!priv->oldlink) {
-                       new_state = 1;
-                       priv->oldlink = 1;
-               }
-       } else if (priv->oldlink) {
-               new_state = 1;
-               priv->oldlink = 0;
-               priv->oldspeed = 0;
-               priv->oldduplex = -1;
-       }
-
-       if (new_state && netif_msg_link(priv))
-               phy_print_status(phydev);
+       if (unlikely(phydev->link != priv->oldlink ||
+                    phydev->duplex != priv->oldduplex ||
+                    phydev->speed != priv->oldspeed))
+               gfar_update_link_state(priv);
 }
 
 /* Update the hash table based on the current list of multicast
@@ -3442,6 +3337,114 @@ static irqreturn_t gfar_error(int irq, void *grp_id)
        return IRQ_HANDLED;
 }
 
+static u32 gfar_get_flowctrl_cfg(struct gfar_private *priv)
+{
+       struct phy_device *phydev = priv->phydev;
+       u32 val = 0;
+
+       if (!phydev->duplex)
+               return val;
+
+       if (!priv->pause_aneg_en) {
+               if (priv->tx_pause_en)
+                       val |= MACCFG1_TX_FLOW;
+               if (priv->rx_pause_en)
+                       val |= MACCFG1_RX_FLOW;
+       } else {
+               u16 lcl_adv, rmt_adv;
+               u8 flowctrl;
+               /* get link partner capabilities */
+               rmt_adv = 0;
+               if (phydev->pause)
+                       rmt_adv = LPA_PAUSE_CAP;
+               if (phydev->asym_pause)
+                       rmt_adv |= LPA_PAUSE_ASYM;
+
+               lcl_adv = mii_advertise_flowctrl(phydev->advertising);
+
+               flowctrl = mii_resolve_flowctrl_fdx(lcl_adv, rmt_adv);
+               if (flowctrl & FLOW_CTRL_TX)
+                       val |= MACCFG1_TX_FLOW;
+               if (flowctrl & FLOW_CTRL_RX)
+                       val |= MACCFG1_RX_FLOW;
+       }
+
+       return val;
+}
+
+static noinline void gfar_update_link_state(struct gfar_private *priv)
+{
+       struct gfar __iomem *regs = priv->gfargrp[0].regs;
+       struct phy_device *phydev = priv->phydev;
+
+       if (unlikely(test_bit(GFAR_RESETTING, &priv->state)))
+               return;
+
+       if (phydev->link) {
+               u32 tempval1 = gfar_read(&regs->maccfg1);
+               u32 tempval = gfar_read(&regs->maccfg2);
+               u32 ecntrl = gfar_read(&regs->ecntrl);
+
+               if (phydev->duplex != priv->oldduplex) {
+                       if (!(phydev->duplex))
+                               tempval &= ~(MACCFG2_FULL_DUPLEX);
+                       else
+                               tempval |= MACCFG2_FULL_DUPLEX;
+
+                       priv->oldduplex = phydev->duplex;
+               }
+
+               if (phydev->speed != priv->oldspeed) {
+                       switch (phydev->speed) {
+                       case 1000:
+                               tempval =
+                                   ((tempval & ~(MACCFG2_IF)) | MACCFG2_GMII);
+
+                               ecntrl &= ~(ECNTRL_R100);
+                               break;
+                       case 100:
+                       case 10:
+                               tempval =
+                                   ((tempval & ~(MACCFG2_IF)) | MACCFG2_MII);
+
+                               /* Reduced mode distinguishes
+                                * between 10 and 100
+                                */
+                               if (phydev->speed == SPEED_100)
+                                       ecntrl |= ECNTRL_R100;
+                               else
+                                       ecntrl &= ~(ECNTRL_R100);
+                               break;
+                       default:
+                               netif_warn(priv, link, priv->ndev,
+                                          "Ack!  Speed (%d) is not 10/100/1000!\n",
+                                          phydev->speed);
+                               break;
+                       }
+
+                       priv->oldspeed = phydev->speed;
+               }
+
+               tempval1 &= ~(MACCFG1_TX_FLOW | MACCFG1_RX_FLOW);
+               tempval1 |= gfar_get_flowctrl_cfg(priv);
+
+               gfar_write(&regs->maccfg1, tempval1);
+               gfar_write(&regs->maccfg2, tempval);
+               gfar_write(&regs->ecntrl, ecntrl);
+
+               if (!priv->oldlink)
+                       priv->oldlink = 1;
+
+       } else if (priv->oldlink) {
+               priv->oldlink = 0;
+               priv->oldspeed = 0;
+               priv->oldduplex = -1;
+       }
+
+       if (netif_msg_link(priv))
+               phy_print_status(phydev);
+}
+
 static struct of_device_id gfar_match[] =
 {
        {