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.
Add serialisation to the MAC reset to eliminate the race condition.
Signed-off-by: John Efstathiades <john.efstathia...@pebblebay.com>
---
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 9bd21d17d6f1..0a6f4765f595 100644
--- a/drivers/net/usb/lan78xx.c
+++ b/drivers/net/usb/lan78xx.c
@@ -1342,6 +1342,52 @@ static int lan78xx_update_flowcontrol(struct lan78xx_net
*dev, u8 duplex,
static void lan78xx_rx_urb_submit_all(struct lan78xx_net *dev);
+static int lan78xx_mac_reset(struct lan78xx_net *dev)
+{
+ u32 val;
+ int ret;
+ unsigned long start_time = jiffies;
+
+ mutex_lock(&dev->phy_mutex);
+
+ /* confirm MII not busy */
+ ret = lan78xx_phy_wait_not_busy(dev);
+ if (ret < 0)
+ goto done;
+
+ ret = lan78xx_read_reg(dev, MAC_CR, &val);
+ if (unlikely(ret < 0)) {
+ ret = -EIO;
+ goto done;
+ }
+
+ val |= MAC_CR_RST_;
+ ret = lan78xx_write_reg(dev, MAC_CR, val);
+ if (unlikely(ret < 0)) {
+ ret = -EIO;
+ goto done;
+ }
+
+ /* poll for completion */
+
+ do {
+ ret = lan78xx_read_reg(dev, MAC_CR, &val);
+ if (unlikely(ret < 0)) {
+ ret = -EIO;
+ break;
+ }
+ if (!(val & MAC_CR_RST_)) {
+ ret = 0;
+ break;
+ }
+ } while (!time_after(jiffies, start_time + HZ));
+
+done:
+ mutex_unlock(&dev->phy_mutex);
+
+ return ret;
+}
+
static int lan78xx_link_reset(struct lan78xx_net *dev)
{
struct phy_device *phydev = dev->net->phydev;
@@ -1360,12 +1406,8 @@ 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 -EIO;
- buf |= MAC_CR_RST_;
- ret = lan78xx_write_reg(dev, MAC_CR, buf);
- if (unlikely(ret < 0))
+ ret = lan78xx_mac_reset(dev);
+ if (unlikely(ret != 0))
return -EIO;
del_timer(&dev->stat_monitor);
--
2.17.1
