[PATCH] 2.6.15: via-rhine + link loss + autoneg off == trouble

[Denis Vlasenko]

Hi,

2.6.15 still exhibits the via rhine "no tx" syndrome.

Again, the recipe:
* have via-rhine NIC
* unplug network cable
* reboot box
* force HDX (I do in with ethtool -s if autoneg off duplex half)
* plug cable back
* kernel still thinks that carrier is off despite "ethtool if"
  saying that link is detected.

Why:

...
        if (intr_status & IntrLinkChange)
                rhine_check_media(dev, 0);
...

static void rhine_check_media(struct net_device *dev, unsigned int init_media)
{
        struct rhine_private *rp = netdev_priv(dev);
        void __iomem *ioaddr = rp->base;

        mii_check_media(&rp->mii_if, debug, init_media);
...

unsigned int mii_check_media (struct mii_if_info *mii,
                              unsigned int ok_to_print,
                              unsigned int init_media)
{
        unsigned int old_carrier, new_carrier;
        int advertise, lpa, media, duplex;
        int lpa2 = 0;

        /* if forced media, go no further */
        if (mii->force_media)   <============================ HERE
                return 0; /* duplex did not change */

        /* check current and old link status */
        old_carrier = netif_carrier_ok(mii->dev) ? 1 : 0;
        new_carrier = (unsigned int) mii_link_ok(mii);

        /* if carrier state did not change, this is a "bounce",
         * just exit as everything is already set correctly
         */
        if ((!init_media) && (old_carrier == new_carrier))
                return 0; /* duplex did not change */

        /* no carrier, nothing much to do */
        if (!new_carrier) {
                netif_carrier_off(mii->dev);
                if (ok_to_print)
                        printk(KERN_INFO "%s: link down\n", mii->dev->name);
                return 0; /* duplex did not change */
        }

        /*
         * we have carrier, see who's on the other end
         */
        netif_carrier_on(mii->dev);
...

We can never reach netif_carrier_on if mii->force_media is true!

> On Friday 11 November 2005 13:32, Jeff Garzik wrote:
> > As I've explained many times at this point, force_media means that link 
> > is always on, and mii_link_ok() should not be called.
> 
> Sorry, seems like I missed your mails...
>  
> > The only bug, it seems, is that the "if (mii->force_media)" branch 
> > should make sure to call netif_carrier_on()
> 
> Should also work.

Please find patch attached.
--
vda
--- linux-2.6.15.org/drivers/net/mii.c	Fri Dec 30 14:17:47 2005
+++ linux-2.6.15/drivers/net/mii.c	Sat Jan  7 18:15:27 2006
@@ -267,8 +267,10 @@ unsigned int mii_check_media (struct mii
 	int lpa2 = 0;
 
 	/* if forced media, go no further */
-	if (mii->force_media)
+	if (mii->force_media) {
+		netif_carrier_on(mii->dev);
 		return 0; /* duplex did not change */
+	}
 
 	/* check current and old link status */
 	old_carrier = netif_carrier_ok(mii->dev) ? 1 : 0;