queue-4.4/net-ks8851-set-initial-carrier-state-to-down.patch

   1 From 531de818fccb2b5064ee33e80b2058034541fe1a Mon Sep 17 00:00:00 2001
   2 From: Lukas Wunner <lukas@wunner.de>
   3 Date: Wed, 20 Mar 2019 15:02:00 +0100
   4 Subject: net: ks8851: Set initial carrier state to down
   5
   6 [ Upstream commit 9624bafa5f6418b9ca5b3f66d1f6a6a2e8bf6d4c ]
   7
   8 The ks8851 chip's initial carrier state is down. A Link Change Interrupt
   9 is signaled once interrupts are enabled if the carrier is up.
  10
  11 The ks8851 driver has it backwards by assuming that the initial carrier
  12 state is up. The state is therefore misrepresented if the interface is
  13 opened with no cable attached. Fix it.
  14
  15 The Link Change interrupt is sometimes not signaled unless the P1MBSR
  16 register (which contains the Link Status bit) is read on ->ndo_open().
  17 This might be a hardware erratum. Read the register by calling
  18 mii_check_link(), which has the desirable side effect of setting the
  19 carrier state to down if the cable was detached while the interface was
  20 closed.
  21
  22 Signed-off-by: Lukas Wunner <lukas@wunner.de>
  23 Cc: Frank Pavlic <f.pavlic@kunbus.de>
  24 Cc: Ben Dooks <ben.dooks@codethink.co.uk>
  25 Cc: Tristram Ha <Tristram.Ha@microchip.com>
  26 Signed-off-by: David S. Miller <davem@davemloft.net>
  27 Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>
  28 ---
  29  drivers/net/ethernet/micrel/ks8851.c | 2 ++
  30  1 file changed, 2 insertions(+)
  31
  32 diff --git a/drivers/net/ethernet/micrel/ks8851.c b/drivers/net/ethernet/micrel/ks8851.c
  33 index ff6cab4f6343..7377dca6eb57 100644
  34 --- a/drivers/net/ethernet/micrel/ks8851.c
  35 +++ b/drivers/net/ethernet/micrel/ks8851.c
  36 @@ -870,6 +870,7 @@ static int ks8851_net_open(struct net_device *dev)
  37         netif_dbg(ks, ifup, ks->netdev, "network device up\n");
  38
  39         mutex_unlock(&ks->lock);
  40 +       mii_check_link(&ks->mii);
  41         return 0;
  42  }
  43
  44 @@ -1527,6 +1528,7 @@ static int ks8851_probe(struct spi_device *spi)
  45
  46         spi_set_drvdata(spi, ks);
  47
  48 +       netif_carrier_off(ks->netdev);
  49         ndev->if_port = IF_PORT_100BASET;
  50         ndev->netdev_ops = &ks8851_netdev_ops;
  51         ndev->irq = spi->irq;
  52 --
  53 2.19.1
  54