Prev: [PATCH] fix race condition in drivers/base/dd.c
Next: fix race condition in drivers/base/dd.c
From: Stefani Seibold on 6 Mar 2010 12:00
This patch fix the PHY poller, which can block the whole system. On a
Freescale PPC 834x this result in a delay of 450 us due the slow
communication with the PHY chip.

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 is more the 100 us on a PPC 834x.

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 every seconds.

Together this patch will prevent a blocking of nearly 400 us every two
seconds of the whole system on a PPC 834x.

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 | 12 +++++++++---
2 files changed, 11 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 +694,16 @@ 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/
 | 
Pages: 1
Prev: [PATCH] fix race condition in drivers/base/dd.c
Next: fix race condition in drivers/base/dd.c