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lan78xx: Debounce link events to minimize poll storm

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The bInterval is set to 4 (i.e. 8 microframes => 1ms) and the only bit
that the driver pays attention to is "link was reset". If there's a
flapping status bit in that endpoint data, (such as if PHY negotiation
needs a few tries to get a stable link) then polling at a slower rate
would act as a de-bounce.

See: https://github.com/raspberrypi/linux/issues/2447
This commit is contained in:
Joshua Emele
2018-11-07 16:07:40 -08:00
committed by Dom Cobley
parent b1deea0371
commit 4824e4d787
1 changed files with 12 additions and 1 deletions
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13
drivers/net/usb/lan78xx.c
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@@ -605,6 +605,11 @@ static bool enable_tso;
module_param(enable_tso, bool, 0644);
MODULE_PARM_DESC(enable_tso, "Enables TCP segmentation offload");
#define INT_URB_MICROFRAMES_PER_MS 8
static int int_urb_interval_ms = 8;
module_param(int_urb_interval_ms, int, 0);
MODULE_PARM_DESC(int_urb_interval_ms, "Override usb interrupt urb interval");
static int lan78xx_read_reg(struct lan78xx_net *dev, u32 index, u32 *data)
{
u32 *buf;
@@ -4735,7 +4740,13 @@ static int lan78xx_probe(struct usb_interface *intf,
if (ret < 0)
goto out4;
period = ep_intr->desc.bInterval;
if (int_urb_interval_ms <= 0)
period = ep_intr->desc.bInterval;
else
period = int_urb_interval_ms * INT_URB_MICROFRAMES_PER_MS;
netif_notice(dev, probe, netdev, "int urb period %d\n", period);
maxp = usb_maxpacket(dev->udev, dev->pipe_intr);
dev->urb_intr = usb_alloc_urb(0, GFP_KERNEL);