[PATCH net-next v2 06/10] lan78xx: Fix exception on link speed change
From: John Efstathiades <hidden>
Date: 2021-08-24 18:57:31
Also in:
linux-usb
Subsystem:
networking drivers, the rest, usb lan78xx ethernet driver, usb networking drivers · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Thangaraj Samynathan, Rengarajan Sundararajan
An exception is sometimes seen when the link speed is changed from auto-negotiation to a fixed speed, or vice versa. The exception occurs when the MAC is reset (due to the link speed change) at the same time as the PHY state machine is accessing a PHY register. The following changes fix this problem. Rework the MAC reset to ensure there is no outstanding MDIO register transaction before the reset and then wait until the reset is complete before allowing any further MAC register access. Signed-off-by: John Efstathiades <redacted> --- drivers/net/usb/lan78xx.c | 54 ++++++++++++++++++++++++++++++++++----- 1 file changed, 48 insertions(+), 6 deletions(-)
diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
index 1909d6003453..2eb853b13c2a 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c@@ -1163,6 +1163,52 @@ static int lan78xx_update_flowcontrol(struct lan78xx_net *dev, u8 duplex, return 0; } +static int lan78xx_mac_reset(struct lan78xx_net *dev) +{ + unsigned long start_time = jiffies; + u32 val; + int ret; + + mutex_lock(&dev->phy_mutex); + + /* Resetting the device while there is activity on the MDIO + * bus can result in the MAC interface locking up and not + * completing register access transactions. + */ + ret = lan78xx_phy_wait_not_busy(dev); + if (ret < 0) + goto done; + + ret = lan78xx_read_reg(dev, MAC_CR, &val); + if (ret < 0) + goto done; + + val |= MAC_CR_RST_; + ret = lan78xx_write_reg(dev, MAC_CR, val); + if (ret < 0) + goto done; + + /* Wait for the reset to complete before allowing any further + * MAC register accesses otherwise the MAC may lock up. + */ + do { + ret = lan78xx_read_reg(dev, MAC_CR, &val); + if (ret < 0) + goto done; + + if (!(val & MAC_CR_RST_)) { + ret = 0; + goto done; + } + } while (!time_after(jiffies, start_time + HZ)); + + ret = -ETIMEDOUT; +done: + mutex_unlock(&dev->phy_mutex); + + return ret; +} + static int lan78xx_link_reset(struct lan78xx_net *dev) { struct phy_device *phydev = dev->net->phydev;
@@ -1184,12 +1230,8 @@ static int lan78xx_link_reset(struct lan78xx_net *dev) dev->link_on = false; /* reset MAC */ - ret = lan78xx_read_reg(dev, MAC_CR, &buf); - if (unlikely(ret < 0)) - return ret; - buf |= MAC_CR_RST_; - ret = lan78xx_write_reg(dev, MAC_CR, buf); - if (unlikely(ret < 0)) + ret = lan78xx_mac_reset(dev); + if (ret < 0) return ret; del_timer(&dev->stat_monitor);
--
2.25.1