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Date: Wed, 26 Mar 2008 10:02:42 -0700 (PDT)
From: khollan <khollan@daktronics.com>
To: linuxppc-embedded@ozlabs.org
Subject: Xilin Temac Timer ?
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Hi

What is the purpose of stopping the timer in the ioctl call to read a PHY
register?  This is the code:

    case SIOCGMIIREG:   /* Read GMII PHY register. */
    case SIOCDEVPRIVATE + 1:    /* for binary compat, remove in 2.5 */
        if (data->phy_id > 31 || data->reg_num > 31)
            return -ENXIO;

        /* Stop the PHY timer to prevent reentrancy. */
        spin_lock_irqsave(&XTE_spinlock, flags);
        del_timer_sync(&lp->phy_timer);

        ret = XTemac_PhyRead(&lp->Emac, data->phy_id,
                       data->reg_num, &data->val_out);

        /* Start the PHY timer up again. */
        lp->phy_timer.expires = jiffies + 2 * HZ;
        add_timer(&lp->phy_timer);
        spin_unlock_irqrestore(&XTE_spinlock, flags);
        if (ret != XST_SUCCESS) {
            printk(KERN_ERR
                   "%s: XTemac: could not read from PHY, error=%d.\n",
                   dev->name, ret);
            return -EBUSY;
        }
        return 0;

I ask because I have an application that needs to read a Phy register before
the timer has started to see if a link is present.  This causes a kernel bug
when trying to run the del_timer_sync function because there is not a
running timer.  I would like to know if it is safe to remove the timer del
and add but keep the spin lock.

Thanks for your help

Kevin
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