net: sfp: allow sfp to probe slow to initialise GPON modules

Some GPON modules (e.g. Huawei MA5671A) take a significant amount of
time to start responding on the I2C bus, contary to the SFF
specifications.

Work around this by implementing a two-level timeout strategy, where
we initially quickly retry for the module, and then use a slower retry
after we exceed a maximum number of quick attempts.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
index 8add54b52f4d98a29b2ab9ccac64ff4eaed2f3fa..3a79f54f7acd3c3da7dfe31ce867b3d241c149a1 100644 (file)
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -167,9 +167,12 @@ static const enum gpiod_flags gpio_flags[] = {
  * The SFF-8472 specifies t_serial ("Time from power on until module is
  * ready for data transmission over the two wire serial bus.") as 300ms.
  */
-#define T_SERIAL       msecs_to_jiffies(300)
-#define T_HPOWER_LEVEL msecs_to_jiffies(300)
-#define T_PROBE_RETRY  msecs_to_jiffies(100)
+#define T_SERIAL               msecs_to_jiffies(300)
+#define T_HPOWER_LEVEL         msecs_to_jiffies(300)
+#define T_PROBE_RETRY_INIT     msecs_to_jiffies(100)
+#define R_PROBE_RETRY_INIT     10
+#define T_PROBE_RETRY_SLOW     msecs_to_jiffies(5000)
+#define R_PROBE_RETRY_SLOW     12
 
 /* SFP modules appear to always have their PHY configured for bus address
  * 0x56 (which with mdio-i2c, translates to a PHY address of 22).
@@ -204,6 +207,8 @@ struct sfp {
        struct delayed_work timeout;
        struct mutex sm_mutex;                  /* Protects state machine */
        unsigned char sm_mod_state;
+       unsigned char sm_mod_tries_init;
+       unsigned char sm_mod_tries;
        unsigned char sm_dev_state;
        unsigned short sm_state;
        unsigned int sm_retries;
@@ -1457,7 +1462,7 @@ static int sfp_sm_mod_hpower(struct sfp *sfp, bool enable)
        return 0;
 }
 
-static int sfp_sm_mod_probe(struct sfp *sfp)
+static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
 {
        /* SFP module inserted - read I2C data */
        struct sfp_eeprom_id id;
@@ -1467,7 +1472,8 @@ static int sfp_sm_mod_probe(struct sfp *sfp)
 
        ret = sfp_read(sfp, false, 0, &id, sizeof(id));
        if (ret < 0) {
-               dev_err(sfp->dev, "failed to read EEPROM: %d\n", ret);
+               if (report)
+                       dev_err(sfp->dev, "failed to read EEPROM: %d\n", ret);
                return -EAGAIN;
        }
 
@@ -1614,8 +1620,11 @@ static void sfp_sm_module(struct sfp *sfp, unsigned int event)
 
        switch (sfp->sm_mod_state) {
        default:
-               if (event == SFP_E_INSERT)
+               if (event == SFP_E_INSERT) {
                        sfp_sm_mod_next(sfp, SFP_MOD_PROBE, T_SERIAL);
+                       sfp->sm_mod_tries_init = R_PROBE_RETRY_INIT;
+                       sfp->sm_mod_tries = R_PROBE_RETRY_SLOW;
+               }
                break;
 
        case SFP_MOD_PROBE:
@@ -1623,10 +1632,19 @@ static void sfp_sm_module(struct sfp *sfp, unsigned int event)
                if (event != SFP_E_TIMEOUT)
                        break;
 
-               err = sfp_sm_mod_probe(sfp);
+               err = sfp_sm_mod_probe(sfp, sfp->sm_mod_tries == 1);
                if (err == -EAGAIN) {
-                       sfp_sm_set_timer(sfp, T_PROBE_RETRY);
-                       break;
+                       if (sfp->sm_mod_tries_init &&
+                          --sfp->sm_mod_tries_init) {
+                               sfp_sm_set_timer(sfp, T_PROBE_RETRY_INIT);
+                               break;
+                       } else if (sfp->sm_mod_tries && --sfp->sm_mod_tries) {
+                               if (sfp->sm_mod_tries == R_PROBE_RETRY_SLOW - 1)
+                                       dev_warn(sfp->dev,
+                                                "please wait, module slow to respond\n");
+                               sfp_sm_set_timer(sfp, T_PROBE_RETRY_SLOW);
+                               break;
+                       }
                }
                if (err < 0) {
                        sfp_sm_mod_next(sfp, SFP_MOD_ERROR, 0);
@@ -1661,7 +1679,7 @@ static void sfp_sm_module(struct sfp *sfp, unsigned int event)
                                sfp_module_remove(sfp->sfp_bus);
                                sfp_sm_mod_next(sfp, SFP_MOD_ERROR, 0);
                        } else {
-                               sfp_sm_set_timer(sfp, T_PROBE_RETRY);
+                               sfp_sm_set_timer(sfp, T_PROBE_RETRY_INIT);
                        }
                        break;
                }