[PATCH] fix PHY polling system blocking
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From: Stefani Seibold on 13 Mar 2010 08:00 This patch fix the PHY poller, which can block the whole system. PHY access are normaly not very fast, since there are serial attached. For PHY chips without interrupts, the status of the ethernet will be polled every 2 sec. The poll function will read some register of the MII PHY. The time between the sending the MII_READ_COMMAND and receiving the result could be very long (>100us). For example: On a Freescale PPC 834x this result in a delay of 450 us due the slow communication with the PHY chip. The time between the sending the MII_READ_COMMAND and receiving the result is more the 100 us on this controller. The patch modifies the poller a lit bit. Only a link status state change will result in a successive detection of the connection type. The poll cycle on the other hand will be increased to one every seconds. All in all this patch will prevent a blocking of f.e nearly 400 us every two seconds of the whole system on a PPC 834x. There is not real drawback, only the detection of a connection type change without unplugging the cable will not work. But this is more an esoteric use case. The patch is against kernel 2.6.33. Please merge it. Signed-off-by: Stefani Seibold <stefani(a)seibold.net> --- phy.c | 5 ++--- phy_device.c | 11 ++++++++--- 2 files changed, 10 insertions(+), 6 deletions(-) diff -u -N -r -p linux-2.6.33.orig/drivers/net/phy/phy.c linux-2.6.33/drivers/net/phy/phy.c --- linux-2.6.33.orig/drivers/net/phy/phy.c 2010-02-24 19:52:17.000000000 +0100 +++ linux-2.6.33/drivers/net/phy/phy.c 2010-02-28 22:53:14.725464101 +0100 @@ -871,9 +871,8 @@ void phy_state_machine(struct work_struc case PHY_RUNNING: /* Only register a CHANGE if we are * polling */ - if (PHY_POLL == phydev->irq) - phydev->state = PHY_CHANGELINK; - break; + if (PHY_POLL != phydev->irq) + break; case PHY_CHANGELINK: err = phy_read_status(phydev); diff -u -N -r -p linux-2.6.33.orig/drivers/net/phy/phy_device.c linux-2.6.33/drivers/net/phy/phy_device.c --- linux-2.6.33.orig/drivers/net/phy/phy_device.c 2010-02-24 19:52:17.000000000 +0100 +++ linux-2.6.33/drivers/net/phy/phy_device.c 2010-02-28 22:53:14.726464145 +0100 @@ -161,7 +161,7 @@ struct phy_device* phy_device_create(str dev->speed = 0; dev->duplex = -1; dev->pause = dev->asym_pause = 0; - dev->link = 1; + dev->link = 0; dev->interface = PHY_INTERFACE_MODE_GMII; dev->autoneg = AUTONEG_ENABLE; @@ -694,10 +694,15 @@ int genphy_update_link(struct phy_device if (status < 0) return status; - if ((status & BMSR_LSTATUS) == 0) + if ((status & BMSR_LSTATUS) == 0) { + if (phydev->link == 0) + return 1; phydev->link = 0; - else + } else { + if (phydev->link == 1) + return 1; phydev->link = 1; + } return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |