target/linux/layerscape/patches-5.4/701-net-0402-drivers-net-dsa-felix-don-t-restart-PCS-SGMII-AN-if-.patch

   1 From 2a2ccfa44e56c45dfd1230f6efb3ec0a4a677f0a Mon Sep 17 00:00:00 2001
   2 From: Alex Marginean <alexandru.marginean@nxp.com>
   3 Date: Wed, 15 Jan 2020 15:49:11 +0200
   4 Subject: [PATCH] drivers: net: dsa: felix: don't restart PCS SGMII AN if not
   5  needed
   6
   7 Some PHYs like VSC8234 don't like it when AN restarts on their system side
   8 and they restart line side AN too, going into an endless link up/down loop.
   9 Don't restart PCS AN if link is up already.
  10
  11 Suggested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
  12 Signed-off-by: Alex Marginean <alexandru.marginean@nxp.com>
  13 ---
  14  drivers/net/dsa/ocelot/felix_vsc9959.c | 15 +++++++++++++++
  15  1 file changed, 15 insertions(+)
  16
  17 --- a/drivers/net/dsa/ocelot/felix_vsc9959.c
  18 +++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
  19 @@ -648,7 +648,22 @@ static void vsc9959_pcs_init_sgmii(struc
  20                                    unsigned int link_an_mode,
  21                                    const struct phylink_link_state *state)
  22  {
  23 +       int bmsr, bmcr;
  24 +
  25         if (link_an_mode == MLO_AN_INBAND) {
  26 +               /* Some PHYs like VSC8234 don't like it when AN restarts on
  27 +                * their system  side and they restart line side AN too, going
  28 +                * into an endless link up/down loop.  Don't restart PCS AN if
  29 +                * link is up already.
  30 +                * We do check that AN is enabled just in case this is the 1st
  31 +                * call, PCS detects a carrier but AN is disabled from power on
  32 +                * or by boot loader.
  33 +                */
  34 +               bmcr = phy_read(pcs, MII_BMCR);
  35 +               bmsr = phy_read(pcs, MII_BMSR);
  36 +               if ((bmcr & BMCR_ANENABLE) && (bmsr & BMSR_LSTATUS))
  37 +                       return;
  38 +
  39                 /* SGMII spec requires tx_config_Reg[15:0] to be exactly 0x4001
  40                  * for the MAC PCS in order to acknowledge the AN.
  41                  */