Messages in this thread Patch in this message | | | Date | Fri, 09 Sep 2005 00:39:18 +0200 | From | Tommy Christensen <> | Subject | Re: [PATCH] 3c59x: read current link status from phy |
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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 <tommy.christensen@tpack.net>
--- 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", | |