target/linux/generic/backport-5.4/729-v5.5-net-sfp-eliminate-mdelay-from-PHY-probe.patch

   1 From 0fe72afaa31f98ebd71bd6683fc47021105d0157 Mon Sep 17 00:00:00 2001
   2 From: Russell King <rmk+kernel@armlinux.org.uk>
   3 Date: Fri, 18 Oct 2019 10:21:46 +0100
   4 Subject: [PATCH 627/660] net: sfp: eliminate mdelay() from PHY probe
   5
   6 Rather than using mdelay() to wait before probing the PHY (which holds
   7 several locks, including the rtnl lock), add an extra wait state to
   8 the state machine to introduce the 50ms delay without holding any
   9 locks.
  10
  11 Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
  12 ---
  13  drivers/net/phy/sfp.c | 52 +++++++++++++++++++++++++++++++++----------
  14  1 file changed, 40 insertions(+), 12 deletions(-)
  15
  16 --- a/drivers/net/phy/sfp.c
  17 +++ b/drivers/net/phy/sfp.c
  18 @@ -54,6 +54,7 @@ enum {
  19         SFP_DEV_UP,
  20
  21         SFP_S_DOWN = 0,
  22 +       SFP_S_WAIT,
  23         SFP_S_INIT,
  24         SFP_S_WAIT_LOS,
  25         SFP_S_LINK_UP,
  26 @@ -110,6 +111,7 @@ static const char *event_to_str(unsigned
  27
  28  static const char * const sm_state_strings[] = {
  29         [SFP_S_DOWN] = "down",
  30 +       [SFP_S_WAIT] = "wait",
  31         [SFP_S_INIT] = "init",
  32         [SFP_S_WAIT_LOS] = "wait_los",
  33         [SFP_S_LINK_UP] = "link_up",
  34 @@ -141,6 +143,7 @@ static const enum gpiod_flags gpio_flags
  35         GPIOD_ASIS,
  36  };
  37
  38 +#define T_WAIT         msecs_to_jiffies(50)
  39  #define T_INIT_JIFFIES msecs_to_jiffies(300)
  40  #define T_RESET_US     10
  41  #define T_FAULT_RECOVER        msecs_to_jiffies(1000)
  42 @@ -161,9 +164,6 @@ static const enum gpiod_flags gpio_flags
  43   */
  44  #define SFP_PHY_ADDR   22
  45
  46 -/* Give this long for the PHY to reset. */
  47 -#define T_PHY_RESET_MS 50
  48 -
  49  struct sff_data {
  50         unsigned int gpios;
  51         bool (*module_supported)(const struct sfp_eeprom_id *id);
  52 @@ -1267,8 +1267,6 @@ static void sfp_sm_probe_phy(struct sfp
  53         struct phy_device *phy;
  54         int err;
  55
  56 -       msleep(T_PHY_RESET_MS);
  57 -
  58         phy = mdiobus_scan(sfp->i2c_mii, SFP_PHY_ADDR);
  59         if (phy == ERR_PTR(-ENODEV)) {
  60                 dev_info(sfp->dev, "no PHY detected\n");
  61 @@ -1623,6 +1621,8 @@ static void sfp_sm_module(struct sfp *sf
  62
  63  static void sfp_sm_main(struct sfp *sfp, unsigned int event)
  64  {
  65 +       unsigned long timeout;
  66 +
  67         /* Some events are global */
  68         if (sfp->sm_state != SFP_S_DOWN &&
  69             (sfp->sm_mod_state != SFP_MOD_PRESENT ||
  70 @@ -1640,17 +1640,45 @@ static void sfp_sm_main(struct sfp *sfp,
  71         /* The main state machine */
  72         switch (sfp->sm_state) {
  73         case SFP_S_DOWN:
  74 -               if (sfp->sm_mod_state == SFP_MOD_PRESENT &&
  75 -                   sfp->sm_dev_state == SFP_DEV_UP) {
  76 -                       sfp_sm_mod_init(sfp);
  77 -                       sfp_sm_probe_for_phy(sfp);
  78 +               if (sfp->sm_mod_state != SFP_MOD_PRESENT ||
  79 +                   sfp->sm_dev_state != SFP_DEV_UP)
  80 +                       break;
  81 +
  82 +               sfp_sm_mod_init(sfp);
  83 +
  84 +               /* Initialise the fault clearance retries */
  85 +               sfp->sm_retries = 5;
  86 +
  87 +               /* We need to check the TX_FAULT state, which is not defined
  88 +                * while TX_DISABLE is asserted. The earliest we want to do
  89 +                * anything (such as probe for a PHY) is 50ms.
  90 +                */
  91 +               sfp_sm_next(sfp, SFP_S_WAIT, T_WAIT);
  92 +               break;
  93 +
  94 +       case SFP_S_WAIT:
  95 +               if (event != SFP_E_TIMEOUT)
  96 +                       break;
  97 +
  98 +               sfp_sm_probe_for_phy(sfp);
  99
 100 +               if (sfp->state & SFP_F_TX_FAULT) {
 101                         /* Wait t_init before indicating that the link is up,
 102                          * provided the current state indicates no TX_FAULT. If
 103                          * TX_FAULT clears before this time, that's fine too.
 104                          */
 105 -                       sfp_sm_next(sfp, SFP_S_INIT, T_INIT_JIFFIES);
 106 -                       sfp->sm_retries = 5;
 107 +                       timeout = T_INIT_JIFFIES;
 108 +                       if (timeout > T_WAIT)
 109 +                               timeout -= T_WAIT;
 110 +                       else
 111 +                               timeout = 1;
 112 +
 113 +                       sfp_sm_next(sfp, SFP_S_INIT, timeout);
 114 +               } else {
 115 +                       /* TX_FAULT is not asserted, assume the module has
 116 +                        * finished initialising.
 117 +                        */
 118 +                       goto init_done;
 119                 }
 120                 break;
 121
 122 @@ -1658,7 +1686,7 @@ static void sfp_sm_main(struct sfp *sfp,
 123                 if (event == SFP_E_TIMEOUT && sfp->state & SFP_F_TX_FAULT)
 124                         sfp_sm_fault(sfp, true);
 125                 else if (event == SFP_E_TIMEOUT || event == SFP_E_TX_CLEAR)
 126 -                       sfp_sm_link_check_los(sfp);
 127 +       init_done:      sfp_sm_link_check_los(sfp);
 128                 break;
 129
 130         case SFP_S_WAIT_LOS: