openwrt/target/linux/generic/backport-5.4/735-v5.5-net-sfp-allow-sfp-to-probe-slow-to-initialise-GPON-m.patch

From fb56cd08880aff8fb030e684fa4311bef712a499 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Tue, 5 Nov 2019 13:02:30 +0000
Subject: [PATCH 633/660] 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>
---
 drivers/net/phy/sfp.c | 38 ++++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 10 deletions(-)

--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -165,9 +165,12 @@ 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).
@@ -202,6 +205,8 @@ 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;
@@ -1392,7 +1397,7 @@ static int sfp_sm_mod_hpower(struct sfp
 	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;
@@ -1402,7 +1407,8 @@ static int sfp_sm_mod_probe(struct 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;
 	}
 
@@ -1549,8 +1555,11 @@ static void sfp_sm_module(struct sfp *sf
 
 	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:
@@ -1558,10 +1567,19 @@ static void sfp_sm_module(struct sfp *sf
 		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);
@@ -1596,7 +1614,7 @@ static void sfp_sm_module(struct sfp *sf
 				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;
 		}