target/linux/bcm27xx/patches-5.4/950-0132-lan78xx-Debounce-link-events-to-minimize-poll-storm.patch

   1 From 20c9da8c7bab3bbc18e42ee0b2659c4b43aabad7 Mon Sep 17 00:00:00 2001
   2 From: Joshua Emele <jemele@acm.org>
   3 Date: Wed, 7 Nov 2018 16:07:40 -0800
   4 Subject: [PATCH] lan78xx: Debounce link events to minimize poll storm
   5
   6 The bInterval is set to 4 (i.e. 8 microframes => 1ms) and the only bit
   7 that the driver pays attention to is "link was reset". If there's a
   8 flapping status bit in that endpoint data, (such as if PHY negotiation
   9 needs a few tries to get a stable link) then polling at a slower rate
  10 would act as a de-bounce.
  11
  12 See: https://github.com/raspberrypi/linux/issues/2447
  13 ---
  14  drivers/net/usb/lan78xx.c | 12 +++++++++++-
  15  1 file changed, 11 insertions(+), 1 deletion(-)
  16 --- a/drivers/net/usb/lan78xx.c
  17 +++ b/drivers/net/usb/lan78xx.c
  18 @@ -434,6 +434,11 @@ static bool enable_tso;
  19  module_param(enable_tso, bool, 0644);
  20  MODULE_PARM_DESC(enable_tso, "Enables TCP segmentation offload");
  21
  22 +#define INT_URB_MICROFRAMES_PER_MS     8
  23 +static int int_urb_interval_ms = 8;
  24 +module_param(int_urb_interval_ms, int, 0);
  25 +MODULE_PARM_DESC(int_urb_interval_ms, "Override usb interrupt urb interval");
  26 +
  27  static int lan78xx_read_reg(struct lan78xx_net *dev, u32 index, u32 *data)
  28  {
  29         u32 *buf = kmalloc(sizeof(u32), GFP_KERNEL);
  30 @@ -3768,7 +3773,12 @@ static int lan78xx_probe(struct usb_inte
  31         netdev->max_mtu = MAX_SINGLE_PACKET_SIZE;
  32         netif_set_gso_max_size(netdev, MAX_SINGLE_PACKET_SIZE - MAX_HEADER);
  33
  34 -       period = ep_intr->desc.bInterval;
  35 +       if (int_urb_interval_ms <= 0)
  36 +               period = ep_intr->desc.bInterval;
  37 +       else
  38 +               period = int_urb_interval_ms * INT_URB_MICROFRAMES_PER_MS;
  39 +
  40 +       netif_notice(dev, probe, netdev, "int urb period %d\n", period);
  41         maxp = usb_maxpacket(dev->udev, dev->pipe_intr, 0);
  42         buf = kmalloc(maxp, GFP_KERNEL);
  43         if (buf) {