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- From 74be3d89db12ba469eaf4ec082599b6ed1e6dc44 Mon Sep 17 00:00:00 2001
- From: Joshua Emele <[email protected]>
- Date: Wed, 7 Nov 2018 16:07:40 -0800
- Subject: [PATCH] lan78xx: Debounce link events to minimize poll storm
- 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
- ---
- drivers/net/usb/lan78xx.c | 13 ++++++++++++-
- 1 file changed, 12 insertions(+), 1 deletion(-)
- --- a/drivers/net/usb/lan78xx.c
- +++ b/drivers/net/usb/lan78xx.c
- @@ -618,6 +618,11 @@ 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;
- @@ -4458,7 +4463,13 @@ static int lan78xx_probe(struct usb_inte
- 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);
- buf = kmalloc(maxp, GFP_KERNEL);
- if (!buf) {
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