NET/PHY: Eliminate the forced speed reduction algorithm. The purpose of the introduced patch is deletion of the forced speed reduction algorithm realisation from the driver module "phy".
The above mentioned algorithm works in the following way: if the phy detected unlink line state (connector plugged off), NIC speed is decreased step-by-step in the sequence: 100 full duplex 100 half duplex 10 full duplex 10 half duplex with the latency circa 10 s per step, and stops at 10-HD value. I have looked up RFC-802.3, and found, that the mentioned algorithm is neither quoted nor described. AFAIK, no one RFC describe the mentioned algorithm, so it may be a witty invention of the developer(s). In the case of the fixed speed and duplex set, with the autonegotiation off, for a NIC (e.g. # ethtool -s eth0 autoneg off speed 100 duplex full) with ethernet cable plugged off, mentioned algorithm slows down NIC speed, so when ethernet connector is plugged in, connection will be inoperative: an ethernet switch will try to connect with 100/full (e.g.), a NIC will stay at 10/half. Thus, this algorithm is destructive for the fixed speed/duplex mode (with autonegotiation off). In the AUTO mode, the mentioned algorithm is inessential. The autonegotiation procedure works fine regardless an speed/duplex settings at the moment of connector hooking up. Thus, there is no point in using of this algorithm in driver. Thanks a lot Francois Romieu and David Miller for very constructive advises. Tested at 2.6.38.7, applicable up to for 3.0.4. Signed-off-by: Kirill Kapranov <[email protected]>,<[email protected]> --- linux/drivers/net/phy/phy.c.orig 2011-05-22 02:13:59.000000000 +0400 +++ linux/drivers/net/phy/phy.c 2012-04-28 12:49:37.000000000 +0400 @@ -457,34 +457,6 @@ void phy_stop_machine(struct phy_device } /** - * phy_force_reduction - reduce PHY speed/duplex settings by one step - * @phydev: target phy_device struct - * - * Description: Reduces the speed/duplex settings by one notch, - * in this order-- - * 1000/FULL, 1000/HALF, 100/FULL, 100/HALF, 10/FULL, 10/HALF. - * The function bottoms out at 10/HALF. - */ -static void phy_force_reduction(struct phy_device *phydev) -{ - int idx; - - idx = phy_find_setting(phydev->speed, phydev->duplex); - - idx++; - - idx = phy_find_valid(idx, phydev->supported); - - phydev->speed = settings[idx].speed; - phydev->duplex = settings[idx].duplex; - - pr_info("Trying %d/%s\n", phydev->speed, - DUPLEX_FULL == phydev->duplex ? - "FULL" : "HALF"); -} - - -/** * phy_error - enter HALTED state for this PHY device * @phydev: target phy_device struct * @@ -814,30 +786,12 @@ void phy_state_machine(struct work_struc phydev->adjust_link(phydev->attached_dev); } else if (0 == phydev->link_timeout--) { - int idx; needs_aneg = 1; /* If we have the magic_aneg bit, * we try again */ if (phydev->drv->flags & PHY_HAS_MAGICANEG) break; - - /* The timer expired, and we still - * don't have a setting, so we try - * forcing it until we find one that - * works, starting from the fastest speed, - * and working our way down */ - idx = phy_find_valid(0, phydev->supported); - - phydev->speed = settings[idx].speed; - phydev->duplex = settings[idx].duplex; - - phydev->autoneg = AUTONEG_DISABLE; - - pr_info("Trying %d/%s\n", phydev->speed, - DUPLEX_FULL == - phydev->duplex ? - "FULL" : "HALF"); } break; case PHY_NOLINK: @@ -863,7 +817,6 @@ void phy_state_machine(struct work_struc netif_carrier_on(phydev->attached_dev); } else { if (0 == phydev->link_timeout--) { - phy_force_reduction(phydev); needs_aneg = 1; } } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
