Bogdan Costescu wrote:
I now understood what the problem was, so I'll put it in words for
posterity: the Link Status bit of the MII Status register needs to be
read twice to first clear the error state (link bit=0) after which the
bit reports the actual value of the link. From the manual:
Yes, this is exactly the point.
But I still don't agree with your solution: you are reading the Status
register twice in all cases, which is wrong. What you want is to read it
a second time only after the link was marked as down: a simple check if
bit 2 of the Status register is 0, in which case you issue the second
read. This still means that there will be 2 reads if the link remains
down, but at least there is only 1 read for the case where the link is
up and remains up.
I don't think this makes much of a difference in the big picture, but
you're certainly right: let's not waste more cycles than we have to.
Can we agree on the patch below?
-Tommy
[3c59x] Avoid blindly reading link status twice
In order to spare some I/O operations, be more intelligent about
when to read from the PHY.
Pointed out by Bogdan Costescu.
Signed-off-by: Tommy S. Christensen <[EMAIL PROTECTED]>
--- linux-2.6.13-git8/drivers/net/3c59x.c-orig Fri Sep 9 00:05:49 2005
+++ linux-2.6.13-git8/drivers/net/3c59x.c Fri Sep 9 00:13:55 2005
@@ -1889,7 +1889,9 @@ vortex_timer(unsigned long data)
{
spin_lock_bh(&vp->lock);
mii_status = mdio_read(dev, vp->phys[0], 1);
- mii_status = mdio_read(dev, vp->phys[0], 1);
+ if (!(mii_status & BMSR_LSTATUS))
+ /* Re-read to get actual link status */
+ mii_status = mdio_read(dev, vp->phys[0], 1);
ok = 1;
if (vortex_debug > 2)
printk(KERN_DEBUG "%s: MII transceiver has
status %4.4x.\n",
