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mcs7830: Fix link state detection 

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 <linux@rainbow-software.org>
Reported-by: Michael Leun <lkml20120218@newton.leun.net>
Tested-by: Michael Leun <lkml20120218@newton.leun.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ondrej Zary 2012-10-11 22:51:41 +00:00 committed by David S. Miller
parent 93ac0ef016
commit dabdaf0caa
1 changed files with 21 additions and 9 deletions
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30
drivers/net/usb/mcs7830.c
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@ -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 = {