[PATCH v2] mcs7830: Fix link state detection
From: Ondrej Zary <hidden>
Date: 2012-10-12 08:52:35
The device had an undocumented "feature": it can provide a sequence of spurious link-down status data even if the link is up all the time. A sequence of 10 was seen so update the link state only after the device reports the same link state 20 times. Signed-off-by: Ondrej Zary <redacted> Reported-by: Michael Leun <redacted> Tested-by: Michael Leun <redacted> --- drivers/net/usb/mcs7830.c | 30 +++++++++++++++++++++--------- 1 files changed, 21 insertions(+), 9 deletions(-)
diff --git a/drivers/net/usb/mcs7830.c b/drivers/net/usb/mcs7830.c
index 03c2d8d..cc7e720 100644
--- a/drivers/net/usb/mcs7830.c
+++ b/drivers/net/usb/mcs7830.c@@ -117,6 +117,7 @@ enum { struct mcs7830_data { u8 multi_filter[8]; u8 config; + u8 link_counter; }; static const char driver_name[] = "MOSCHIP usb-ethernet driver";
@@ -632,20 +633,31 @@ static int mcs7830_rx_fixup(struct usbnet *dev, struct sk_buff *skb) static void mcs7830_status(struct usbnet *dev, struct urb *urb) { u8 *buf = urb->transfer_buffer; - bool link; + bool link, link_changed; + struct mcs7830_data *data = mcs7830_get_data(dev); if (urb->actual_length < 16) return; link = !(buf[1] & 0x20); - if (netif_carrier_ok(dev->net) != link) { - if (link) { - netif_carrier_on(dev->net); - usbnet_defer_kevent(dev, EVENT_LINK_RESET); - } else - netif_carrier_off(dev->net); - netdev_dbg(dev->net, "Link Status is: %d\n", link); - } + link_changed = netif_carrier_ok(dev->net) != link; + if (link_changed) { + data->link_counter++; + /* + track link state 20 times to guard against erroneous + link state changes reported sometimes by the chip + */ + if (data->link_counter > 20) { + data->link_counter = 0; + if (link) { + netif_carrier_on(dev->net); + usbnet_defer_kevent(dev, EVENT_LINK_RESET); + } else + netif_carrier_off(dev->net); + netdev_dbg(dev->net, "Link Status is: %d\n", link); + } + } else + data->link_counter = 0; } static const struct driver_info moschip_info = {
--
Ondrej Zary