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authorTrent Piepho <tpiepho@freescale.com>2008-09-24 10:55:46 +0000
committerDavid S. Miller <davem@davemloft.net>2008-10-08 15:43:54 -0700
commit51e2a3846eab18711f4eb59cd0a4c33054e2980a (patch)
treea9abbddd407ce2205218148ebdcf8f54709f6a1c /drivers/net/phy/phy_device.c
parent7bf6bf4803df1adc927f585168d2135fb019c698 (diff)
downloadlinux-linaro-android-51e2a3846eab18711f4eb59cd0a4c33054e2980a.tar.gz
PHY: Avoid unnecessary aneg restarts
The PHY's aneg is configured and restarted whenever the link is brought up, e.g. when DHCP is started after the kernel has booted. This can take the link down for several seconds while auto-negotiation is redone. If the advertised features haven't changed, then it shouldn't be necessary to bring down the link and start auto-negotiation over again. genphy_config_advert() is enhanced to return 0 when the advertised features haven't been changed and >0 when they have been. genphy_config_aneg() then uses this information to not call genphy_restart_aneg() if there has been no change. Signed-off-by: Trent Piepho <tpiepho@freescale.com> Acked-by: Andy Fleming <afleming@freescale.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/phy/phy_device.c')
-rw-r--r--drivers/net/phy/phy_device.c49
1 files changed, 30 insertions, 19 deletions
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 16a0e7de588..17162748005 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -419,13 +419,14 @@ EXPORT_SYMBOL(phy_detach);
*
* Description: Writes MII_ADVERTISE with the appropriate values,
* after sanitizing the values to make sure we only advertise
- * what is supported.
+ * what is supported. Returns < 0 on error, 0 if the PHY's advertisement
+ * hasn't changed, and > 0 if it has changed.
*/
int genphy_config_advert(struct phy_device *phydev)
{
u32 advertise;
- int adv;
- int err;
+ int oldadv, adv;
+ int err, changed = 0;
/* Only allow advertising what
* this PHY supports */
@@ -433,7 +434,7 @@ int genphy_config_advert(struct phy_device *phydev)
advertise = phydev->advertising;
/* Setup standard advertisement */
- adv = phy_read(phydev, MII_ADVERTISE);
+ oldadv = adv = phy_read(phydev, MII_ADVERTISE);
if (adv < 0)
return adv;
@@ -453,15 +454,18 @@ int genphy_config_advert(struct phy_device *phydev)
if (advertise & ADVERTISED_Asym_Pause)
adv |= ADVERTISE_PAUSE_ASYM;
- err = phy_write(phydev, MII_ADVERTISE, adv);
+ if (adv != oldadv) {
+ err = phy_write(phydev, MII_ADVERTISE, adv);
- if (err < 0)
- return err;
+ if (err < 0)
+ return err;
+ changed = 1;
+ }
/* Configure gigabit if it's supported */
if (phydev->supported & (SUPPORTED_1000baseT_Half |
SUPPORTED_1000baseT_Full)) {
- adv = phy_read(phydev, MII_CTRL1000);
+ oldadv = adv = phy_read(phydev, MII_CTRL1000);
if (adv < 0)
return adv;
@@ -471,13 +475,17 @@ int genphy_config_advert(struct phy_device *phydev)
adv |= ADVERTISE_1000HALF;
if (advertise & SUPPORTED_1000baseT_Full)
adv |= ADVERTISE_1000FULL;
- err = phy_write(phydev, MII_CTRL1000, adv);
- if (err < 0)
- return err;
+ if (adv != oldadv) {
+ err = phy_write(phydev, MII_CTRL1000, adv);
+
+ if (err < 0)
+ return err;
+ changed = 1;
+ }
}
- return adv;
+ return changed;
}
EXPORT_SYMBOL(genphy_config_advert);
@@ -561,19 +569,22 @@ int genphy_restart_aneg(struct phy_device *phydev)
*/
int genphy_config_aneg(struct phy_device *phydev)
{
- int err = 0;
+ int result = 0;
if (AUTONEG_ENABLE == phydev->autoneg) {
- err = genphy_config_advert(phydev);
+ int result = genphy_config_advert(phydev);
- if (err < 0)
- return err;
+ if (result < 0) /* error */
+ return result;
- err = genphy_restart_aneg(phydev);
+ /* Only restart aneg if we are advertising something different
+ * than we were before. */
+ if (result > 0)
+ result = genphy_restart_aneg(phydev);
} else
- err = genphy_setup_forced(phydev);
+ result = genphy_setup_forced(phydev);
- return err;
+ return result;
}
EXPORT_SYMBOL(genphy_config_aneg);