From: Lukas Wunner lukas@wunner.de
[ Upstream commit 8960f878e39fadc03d74292a6731f1e914cf2019 ]
When a PHY interrupt is signaled, the SMSC LAN95xx driver updates the MAC full duplex mode and PHY flow control registers based on cached data in struct phy_device:
smsc95xx_status() # raises EVENT_LINK_RESET usbnet_deferred_kevent() smsc95xx_link_reset() # uses cached data in phydev
Simultaneously, phylib polls link status once per second and updates that cached data:
phy_state_machine() phy_check_link_status() phy_read_status() lan87xx_read_status() genphy_read_status() # updates cached data in phydev
If smsc95xx_link_reset() wins the race against genphy_read_status(), the registers may be updated based on stale data.
E.g. if the link was previously down, phydev->duplex is set to DUPLEX_UNKNOWN and that's what smsc95xx_link_reset() will use, even though genphy_read_status() may update it to DUPLEX_FULL afterwards.
PHY interrupts are currently only enabled on suspend to trigger wakeup, so the impact of the race is limited, but we're about to enable them perpetually.
Avoid the race by delaying execution of smsc95xx_link_reset() until phy_state_machine() has done its job and calls back via smsc95xx_handle_link_change().
Signaling EVENT_LINK_RESET on wakeup is not necessary because phylib picks up link status changes through polling. So drop the declaration of a ->link_reset() callback.
Note that the semicolon on a line by itself added in smsc95xx_status() is a placeholder for a function call which will be added in a subsequent commit. That function call will actually handle the INT_ENP_PHY_INT_ interrupt.
Tested-by: Oleksij Rempel o.rempel@pengutronix.de # LAN9514/9512/9500 Tested-by: Ferry Toth fntoth@gmail.com # LAN9514 Signed-off-by: Lukas Wunner lukas@wunner.de Reviewed-by: Andrew Lunn andrew@lunn.ch Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/usb/smsc95xx.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/drivers/net/usb/smsc95xx.c b/drivers/net/usb/smsc95xx.c index c33089168880..7cf9206638c3 100644 --- a/drivers/net/usb/smsc95xx.c +++ b/drivers/net/usb/smsc95xx.c @@ -564,7 +564,7 @@ static int smsc95xx_phy_update_flowcontrol(struct usbnet *dev) return smsc95xx_write_reg(dev, AFC_CFG, afc_cfg); }
-static int smsc95xx_link_reset(struct usbnet *dev) +static void smsc95xx_mac_update_fullduplex(struct usbnet *dev) { struct smsc95xx_priv *pdata = dev->driver_priv; unsigned long flags; @@ -581,14 +581,16 @@ static int smsc95xx_link_reset(struct usbnet *dev) spin_unlock_irqrestore(&pdata->mac_cr_lock, flags);
ret = smsc95xx_write_reg(dev, MAC_CR, pdata->mac_cr); - if (ret < 0) - return ret; + if (ret < 0) { + if (ret != -ENODEV) + netdev_warn(dev->net, + "Error updating MAC full duplex mode\n"); + return; + }
ret = smsc95xx_phy_update_flowcontrol(dev); if (ret < 0) netdev_warn(dev->net, "Error updating PHY flow control\n"); - - return ret; }
static void smsc95xx_status(struct usbnet *dev, struct urb *urb) @@ -605,7 +607,7 @@ static void smsc95xx_status(struct usbnet *dev, struct urb *urb) netif_dbg(dev, link, dev->net, "intdata: 0x%08X\n", intdata);
if (intdata & INT_ENP_PHY_INT_) - usbnet_defer_kevent(dev, EVENT_LINK_RESET); + ; else netdev_warn(dev->net, "unexpected interrupt, intdata=0x%08X\n", intdata); @@ -1062,6 +1064,7 @@ static void smsc95xx_handle_link_change(struct net_device *net) struct usbnet *dev = netdev_priv(net);
phy_print_status(net->phydev); + smsc95xx_mac_update_fullduplex(dev); usbnet_defer_kevent(dev, EVENT_LINK_CHANGE); }
@@ -1967,7 +1970,6 @@ static const struct driver_info smsc95xx_info = { .description = "smsc95xx USB 2.0 Ethernet", .bind = smsc95xx_bind, .unbind = smsc95xx_unbind, - .link_reset = smsc95xx_link_reset, .reset = smsc95xx_reset, .check_connect = smsc95xx_start_phy, .stop = smsc95xx_stop,