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generic: 6.18: backport SFP I2C presence detection without MOD_DEF0 GPIO

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Backport upstream net-next commit 8ac44d24c3a1. An SFP cage whose MOD_DEF0
signal is not wired to a readable GPIO currently uses sff_gpio_get_state(),
which always reports the module present: an empty cage gets stuck in
MOD_ERROR, hot-insertion is never detected and empty cages spam -EIO at
boot. Derive presence from a throttled single-byte I2C read of the module
EEPROM instead, so hot-plug works and the boot spam stops. A soldered-down
"sff,sff" module stays always-present.

This helps RTL93xx SFP boards that route no cage presence signal to a GPIO.

Remaining sfp.c patches refreshed.

Link: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=8ac44d24c3a1
Signed-off-by: Carlo Szelinsky <github@szelinsky.de>
Link: https://github.com/openwrt/openwrt/pull/23836
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
This commit is contained in:
Carlo Szelinsky
2026-06-17 08:53:33 +02:00
committed by Jonas Jelonek
parent 279ad92923
commit cc5e8c5af5
7 changed files with 164 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files
target/linux/generic/backport-6.18/711-v7.2-net-phy-sfp-detect-presence-via-I2C-when-no-MOD_DEF0-GPIO.patch
+156
View File
@@ -0,0 +1,156 @@
From 8ac44d24c3a148c4177bd3ad790c377279f4674f Mon Sep 17 00:00:00 2001
From: Greg Patrick <gregspatrick@hotmail.com>
Date: Thu, 11 Jun 2026 17:53:41 +0000
Subject: [PATCH] net: phy: sfp: detect presence via I2C when no MOD_DEF0 GPIO
An SFP cage (compatible "sff,sfp") whose MOD_DEF0 signal is not wired to a
GPIO currently falls back to sff_gpio_get_state(), which unconditionally
reports the module as present. An empty cage therefore fails its probe and
is parked in SFP_MOD_ERROR forever; because SFP_F_PRESENT never deasserts
there is no REMOVE event to recover the state machine, so a module inserted
after boot is never detected, and empty cages spam -EIO at boot.
This affects boards that route none of the cage presence signal to a
software-readable input. On the NicGiga S100-0800S-M (RTL9303, 8x SFP+) the
cage I2C bus is the switch's SMBus master; TX_DISABLE is driven via a
PCA9534 I/O expander, but no MOD_ABS/MOD_DEF0 line reaches a readable GPIO
(the RTL9303 gpio0 lines read stuck-low, the single PCA9534 is fully
consumed by TX_DISABLE, and there is no RTL8231). The Horaco ZX-SW82TS-L2P
(RTL9302D, 2x SFP+) is independently affected in the same way.
For such an SFP cage, derive presence from a throttled single-byte I2C read
of the module EEPROM instead: a successful read asserts SFP_F_PRESENT,
R_PROBE_ABSENT consecutive failures clear it (to ride out a transient error
on a live module). The existing poll then emits SFP_E_INSERT / SFP_E_REMOVE
normally, giving working hot-plug and silencing the boot-time -EIO spam on
empty cages. Presence is re-probed every T_PROBE_PRESENT, so insertion is
detected within that interval and removal within
T_PROBE_PRESENT * R_PROBE_ABSENT.
A soldered-down module (compatible "sff,sff") has no presence signal and is
genuinely always present, so it continues to use sff_gpio_get_state(); the
new path is gated on the cage type advertising SFP_F_PRESENT.
Signed-off-by: Greg Patrick <gregspatrick@hotmail.com>
Tested-by: Manuel Stocker <mensi@mensi.ch>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/20260611175341.2223184-1-gregspatrick@hotmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
drivers/net/phy/sfp.c | 83 +++++++++++++++++++++++++++++++++++++++++--
1 file changed, 80 insertions(+), 3 deletions(-)
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -206,6 +206,16 @@ static const enum gpiod_flags gpio_flags
#define T_PROBE_RETRY_SLOW msecs_to_jiffies(5000)
#define R_PROBE_RETRY_SLOW 12
+/* Polling interval and consecutive-failure threshold for the I2C presence
+ * probe used on boards without a MOD_DEF0 GPIO (see sfp_i2c_get_state()).
+ * A single successful read asserts presence immediately; R_PROBE_ABSENT
+ * consecutive failures are required to declare a live module removed, to ride
+ * out a transient I2C error. Insertion is thus detected within
+ * T_PROBE_PRESENT and removal within T_PROBE_PRESENT * R_PROBE_ABSENT.
+ */
+#define T_PROBE_PRESENT msecs_to_jiffies(500)
+#define R_PROBE_ABSENT 3
+
/* SFP modules appear to always have their PHY configured for bus address
* 0x56 (which with mdio-i2c, translates to a PHY address of 22).
* RollBall SFPs access phy via SFP Enhanced Digital Diagnostic Interface
@@ -249,6 +259,13 @@ struct sfp {
bool need_poll;
+ /* I2C-probed presence, for boards without a MOD_DEF0 GPIO.
+ * Access rules: st_mutex held (updated from the poll/state machine).
+ */
+ bool i2c_present;
+ u8 i2c_present_nak;
+ unsigned long i2c_present_next;
+
/* Access rules:
* state_hw_drive: st_mutex held
* state_hw_mask: st_mutex held
@@ -860,6 +877,45 @@ static int sfp_read(struct sfp *sfp, boo
return sfp->read(sfp, a2, addr, buf, len);
}
+/* Probe whether a module is physically present by attempting a single-byte
+ * I2C read of the EEPROM identifier (an empty cage NAKs). Used as the presence
+ * source on boards that do not wire MOD_DEF0 to a GPIO.
+ */
+static bool sfp_module_present_i2c(struct sfp *sfp)
+{
+ u8 id;
+
+ return sfp_read(sfp, false, SFP_PHYS_ID, &id, sizeof(id)) == sizeof(id);
+}
+
+/* get_state variant for boards without a MOD_DEF0 GPIO. Instead of assuming
+ * the module is always present, derive SFP_F_PRESENT from a throttled I2C
+ * probe so that hot-insertion and removal are detected. A single ACK asserts
+ * presence; R_PROBE_ABSENT consecutive failures clear it, to ride out a
+ * transient I2C error on a live module.
+ */
+static unsigned int sfp_i2c_get_state(struct sfp *sfp)
+{
+ unsigned int state = sfp_gpio_get_state(sfp);
+
+ if (time_after_eq(jiffies, sfp->i2c_present_next)) {
+ if (sfp_module_present_i2c(sfp)) {
+ sfp->i2c_present = true;
+ sfp->i2c_present_nak = 0;
+ } else if (sfp->i2c_present &&
+ ++sfp->i2c_present_nak >= R_PROBE_ABSENT) {
+ sfp->i2c_present = false;
+ sfp->i2c_present_nak = 0;
+ }
+ sfp->i2c_present_next = jiffies + T_PROBE_PRESENT;
+ }
+
+ if (sfp->i2c_present)
+ state |= SFP_F_PRESENT;
+
+ return state;
+}
+
static int sfp_write(struct sfp *sfp, bool a2, u8 addr, void *buf, size_t len)
{
return sfp->write(sfp, a2, addr, buf, len);
@@ -3158,9 +3214,30 @@ static int sfp_probe(struct platform_dev
sfp->get_state = sfp_gpio_get_state;
sfp->set_state = sfp_gpio_set_state;
- /* Modules that have no detect signal are always present */
- if (!(sfp->gpio[GPIO_MODDEF0]))
- sfp->get_state = sff_gpio_get_state;
+ /* An SFP cage with no MOD_DEF0 GPIO has no hardware presence signal.
+ * Assuming the module is always present traps an empty cage in
+ * MOD_ERROR and never detects hot-insertion, so derive presence from a
+ * throttled I2C probe and poll for changes instead. sfp_i2c_configure()
+ * has already set i2c_max_block_size; seed i2c_block_size so the
+ * presence read does not issue a zero-length transfer before the first
+ * EEPROM read. Seed i2c_present_next to jiffies so the first probe
+ * happens immediately (a zero value would be in the past relative to
+ * the negative INITIAL_JIFFIES at boot and delay detection).
+ *
+ * A soldered-down module (sff,sff) has no presence signal and is
+ * genuinely always present, so it keeps the always-present behaviour;
+ * the I2C probe is gated on the cage type advertising SFP_F_PRESENT.
+ */
+ if (!sfp->gpio[GPIO_MODDEF0]) {
+ if (sff->gpios & SFP_F_PRESENT) {
+ sfp->get_state = sfp_i2c_get_state;
+ sfp->i2c_block_size = sfp->i2c_max_block_size;
+ sfp->i2c_present_next = jiffies;
+ sfp->need_poll = true;
+ } else {
+ sfp->get_state = sff_gpio_get_state;
+ }
+ }
device_property_read_u32(&pdev->dev, "maximum-power-milliwatt",
&sfp->max_power_mW);
target/linux/generic/pending-6.18/750-net-sfp-add-quirk-for-QINIYEK-BJ-SFP-10G-T-copper-SF.patch
+1 -1
View File
@@ -16,7 +16,7 @@ Signed-off-by: Daniel Golle <daniel@makrotopia.org>
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -585,6 +585,7 @@ static const struct sfp_quirk sfp_quirks
@@ -602,6 +602,7 @@ static const struct sfp_quirk sfp_quirks
SFP_QUIRK_S("OEM", "SFP-2.5G-BX10-U", sfp_quirk_2500basex),
SFP_QUIRK_F("OEM", "RTSFP-10", sfp_fixup_rollball_cc),
SFP_QUIRK_F("OEM", "RTSFP-10G", sfp_fixup_rollball_cc),
target/linux/generic/pending-6.18/751-net-sfp-add-quirk-for-TP-LINK-SM410U.patch
+1 -1
View File
@@ -14,7 +14,7 @@ Signed-off-by: Daniel Golle <daniel@makrotopia.org>
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -591,6 +591,7 @@ static const struct sfp_quirk sfp_quirks
@@ -608,6 +608,7 @@ static const struct sfp_quirk sfp_quirks
SFP_QUIRK_F("Turris", "RTSFP-10G", sfp_fixup_rollball),
SFP_QUIRK_S("ZOERAX", "SFP-2.5G-T", sfp_quirk_oem_2_5g),
target/linux/realtek/patches-6.18/705-v7.1-net-sfp-initialize-i2c_block_size-at-adapter-configu.patch
+1 -1
View File
@@ -31,7 +31,7 @@ Signed-off-by: Jakub Kicinski <kuba@kernel.org>
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -824,6 +824,7 @@ static int sfp_i2c_configure(struct sfp
@@ -841,6 +841,7 @@ static int sfp_i2c_configure(struct sfp
return -EINVAL;
}
target/linux/realtek/patches-6.18/706-01-v7.2-net-sfp-apply-I2C-adapter-quirks-to-limit-block-size.patch
+1 -1
View File
@@ -24,7 +24,7 @@ Signed-off-by: Jakub Kicinski <kuba@kernel.org>
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -809,21 +809,29 @@ static int sfp_smbus_byte_write(struct s
@@ -826,21 +826,29 @@ static int sfp_smbus_byte_write(struct s
static int sfp_i2c_configure(struct sfp *sfp, struct i2c_adapter *i2c)
{
target/linux/realtek/patches-6.18/706-02-v7.2-net-sfp-extend-SMBus-support.patch
+2 -2
View File
@@ -75,7 +75,7 @@ Signed-off-by: Jakub Kicinski <kuba@kernel.org>
#include <linux/workqueue.h>
#include "sfp.h"
@@ -758,50 +759,113 @@ static int sfp_i2c_write(struct sfp *sfp
@@ -775,50 +776,113 @@ static int sfp_i2c_write(struct sfp *sfp
return ret == ARRAY_SIZE(msgs) ? len : 0;
}
@@ -213,7 +213,7 @@ Signed-off-by: Jakub Kicinski <kuba@kernel.org>
}
return data - (u8 *)buf;
@@ -817,10 +881,29 @@ static int sfp_i2c_configure(struct sfp
@@ -834,10 +898,29 @@ static int sfp_i2c_configure(struct sfp
sfp->read = sfp_i2c_read;
sfp->write = sfp_i2c_write;
max_block_size = SFP_EEPROM_BLOCK_SIZE;
target/linux/realtek/patches-6.18/714-net-phy-sfp-add-support-for-SMBus.patch
+2 -2
View File
@@ -10,7 +10,7 @@ Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -942,6 +942,29 @@ static int sfp_i2c_mdiobus_create(struct
@@ -959,6 +959,29 @@ static int sfp_i2c_mdiobus_create(struct
return 0;
}
@@ -40,7 +40,7 @@ Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
static void sfp_i2c_mdiobus_destroy(struct sfp *sfp)
{
mdiobus_unregister(sfp->i2c_mii);
@@ -2116,9 +2139,15 @@ static void sfp_sm_fault(struct sfp *sfp
@@ -2172,9 +2195,15 @@ static void sfp_sm_fault(struct sfp *sfp
static int sfp_sm_add_mdio_bus(struct sfp *sfp)
{