[PATCH net-next 0/2] net: sfp: quirk support for XGS-PON ONT sticks with unclean EEPROMs

[PATCH net-next 0/2] net: sfp: quirk support for XGS-PON ONT sticks with unclean EEPROMs

[Martino Dell'Ambrogio]

Some clone XGS-PON ONT sticks ship EEPROMs where the vendor PN field is
filled with non-printable garbage past the legitimate string instead of
the SFF-8472 mandated space padding. sfp_strlen() then can't trim the
field, the exact-length check in sfp_match() rejects the quirk entry
before the string comparison runs, and the quirk silently never applies
— so the kernel honors the module's spurious TX_FAULT and eventually
disables it.

Patch 1 adds an opt-in prefix-matching flag to the quirk table so such
modules can still be matched; existing exact-match entries behave
exactly as before. Patch 2 adds the two entries that need it: the
"OEM" XGSPONST2001 and the Fiberstore XGS-SFP-ONT-MACI, both wired to
the existing potron fixup.

Both quirks are in production use on a Bananapi BPI-R4 (MT7988A)
router on an XGS-PON uplink, backported onto 6.12.

Martino Dell'Ambrogio (2):
  net: sfp: allow prefix matching in quirk lookup
  net: sfp: add quirks for OEM XGSPONST2001 and FS XGS-SFP-ONT-MACI

 drivers/net/phy/sfp.c | 37 ++++++++++++++++++++++++++++++++-----
 drivers/net/phy/sfp.h |  1 +
 2 files changed, 33 insertions(+), 5 deletions(-)

-- 
2.47.3

[PATCH net-next 1/2] net: sfp: allow prefix matching in quirk lookup

[Martino Dell'Ambrogio]

Some clone SFP modules (notably XGS-PON ONT sticks) ship malformed
EEPROMs where the vendor PN field is filled with non-printable garbage
past the trailing legitimate characters instead of SFF-8472 mandated
space padding. The current sfp_match() requires an exact full-field
length match: sfp_strlen() returns 16 (no trailing spaces or NULs to
strip), but strlen() of the quirk string is shorter, so the length
comparison rejects the entry before strncmp() is even called and the
quirk silently never applies. The kernel then honors the module's
spurious TX_FAULT signal and the SFP state machine eventually disables
the module.

Add a prefix_match flag to struct sfp_quirk and a SFP_QUIRK_F_PREFIX
macro. When set, sfp_match() compares only strlen() leading bytes of
the quirk string, ignoring trailing field bytes. Existing exact-match
quirks are unaffected (prefix_match defaults to false via zero-init in
the existing SFP_QUIRK macros).

Signed-off-by: Martino Dell'Ambrogio <tillo@tillo.ch>
---
 drivers/net/phy/sfp.c | 22 +++++++++++++++++-----
 drivers/net/phy/sfp.h |  1 +
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
index f520206..e7ba642 100644
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -516,6 +516,13 @@ static void sfp_quirk_ubnt_uf_instant(const struct sfp_eeprom_id *id,
 	{ .vendor = _v, .part = _p, .support = _s, .fixup = _f, }
 #define SFP_QUIRK_S(_v, _p, _s) SFP_QUIRK(_v, _p, _s, NULL)
 #define SFP_QUIRK_F(_v, _p, _f) SFP_QUIRK(_v, _p, NULL, _f)
+/* Like SFP_QUIRK_F, but matches as a prefix. Use for clone modules
+ * that fill EEPROM trailing bytes with garbage instead of the
+ * SFF-8472-mandated space padding, so sfp_strlen can't trim the
+ * field down to the legitimate length.
+ */
+#define SFP_QUIRK_F_PREFIX(_v, _p, _f) \
+	{ .vendor = _v, .part = _p, .support = NULL, .fixup = _f, .prefix_match = true }
 
 static const struct sfp_quirk sfp_quirks[] = {
 	// Alcatel Lucent G-010S-P can operate at 2500base-X, but incorrectly
@@ -626,13 +633,16 @@ static size_t sfp_strlen(const char *str, size_t maxlen)
 	return size;
 }
 
-static bool sfp_match(const char *qs, const char *str, size_t len)
+static bool sfp_match(const char *qs, const char *str, size_t len, bool prefix)
 {
+	size_t qs_len;
+
 	if (!qs)
 		return true;
-	if (strlen(qs) != len)
+	qs_len = strlen(qs);
+	if (prefix ? qs_len > len : qs_len != len)
 		return false;
-	return !strncmp(qs, str, len);
+	return !strncmp(qs, str, qs_len);
 }
 
 static const struct sfp_quirk *sfp_lookup_quirk(const struct sfp_eeprom_id *id)
@@ -645,8 +655,10 @@ static const struct sfp_quirk *sfp_lookup_quirk(const struct sfp_eeprom_id *id)
 	ps = sfp_strlen(id->base.vendor_pn, ARRAY_SIZE(id->base.vendor_pn));
 
 	for (i = 0, q = sfp_quirks; i < ARRAY_SIZE(sfp_quirks); i++, q++)
-		if (sfp_match(q->vendor, id->base.vendor_name, vs) &&
-		    sfp_match(q->part, id->base.vendor_pn, ps))
+		if (sfp_match(q->vendor, id->base.vendor_name, vs,
+			      q->prefix_match) &&
+		    sfp_match(q->part, id->base.vendor_pn, ps,
+			      q->prefix_match))
 			return q;
 
 	return NULL;
diff --git a/drivers/net/phy/sfp.h b/drivers/net/phy/sfp.h
index 879dff7..867e45e 100644
--- a/drivers/net/phy/sfp.h
+++ b/drivers/net/phy/sfp.h
@@ -12,6 +12,7 @@ struct sfp_quirk {
 	void (*support)(const struct sfp_eeprom_id *id,
 			struct sfp_module_caps *caps);
 	void (*fixup)(struct sfp *sfp);
+	bool prefix_match;
 };
 
 struct sfp_socket_ops {
-- 
2.47.3

Re: [PATCH net-next 1/2] net: sfp: allow prefix matching in quirk lookup

[Maxime Chevallier]

Hi,

On 7/5/26 20:54, Martino Dell'Ambrogio wrote:
> Some clone SFP modules (notably XGS-PON ONT sticks) ship malformed
> EEPROMs where the vendor PN field is filled with non-printable garbage
> past the trailing legitimate characters instead of SFF-8472 mandated
> space padding.

:(

> The current sfp_match() requires an exact full-field
> length match: sfp_strlen() returns 16 (no trailing spaces or NULs to
> strip), but strlen() of the quirk string is shorter, so the length
> comparison rejects the entry before strncmp() is even called and the
> quirk silently never applies. The kernel then honors the module's
> spurious TX_FAULT signal and the SFP state machine eventually disables
> the module.
> 
> Add a prefix_match flag to struct sfp_quirk and a SFP_QUIRK_F_PREFIX
> macro. When set, sfp_match() compares only strlen() leading bytes of
> the quirk string, ignoring trailing field bytes. Existing exact-match
> quirks are unaffected (prefix_match defaults to false via zero-init in
> the existing SFP_QUIRK macros).
> 
> Signed-off-by: Martino Dell'Ambrogio <tillo@tillo.ch>
> ---
>  drivers/net/phy/sfp.c | 22 +++++++++++++++++-----
>  drivers/net/phy/sfp.h |  1 +
>  2 files changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
> index f520206..e7ba642 100644
> --- a/drivers/net/phy/sfp.c
> +++ b/drivers/net/phy/sfp.c
> @@ -516,6 +516,13 @@ static void sfp_quirk_ubnt_uf_instant(const struct sfp_eeprom_id *id,
>  	{ .vendor = _v, .part = _p, .support = _s, .fixup = _f, }
>  #define SFP_QUIRK_S(_v, _p, _s) SFP_QUIRK(_v, _p, _s, NULL)
>  #define SFP_QUIRK_F(_v, _p, _f) SFP_QUIRK(_v, _p, NULL, _f)
> +/* Like SFP_QUIRK_F, but matches as a prefix. Use for clone modules
> + * that fill EEPROM trailing bytes with garbage instead of the
> + * SFF-8472-mandated space padding, so sfp_strlen can't trim the
> + * field down to the legitimate length.
> + */
> +#define SFP_QUIRK_F_PREFIX(_v, _p, _f) \
> +	{ .vendor = _v, .part = _p, .support = NULL, .fixup = _f, .prefix_match = true }
>  
>  static const struct sfp_quirk sfp_quirks[] = {
>  	// Alcatel Lucent G-010S-P can operate at 2500base-X, but incorrectly
> @@ -626,13 +633,16 @@ static size_t sfp_strlen(const char *str, size_t maxlen)
>  	return size;
>  }
>  
> -static bool sfp_match(const char *qs, const char *str, size_t len)
> +static bool sfp_match(const char *qs, const char *str, size_t len, bool prefix)
>  {
> +	size_t qs_len;
> +
>  	if (!qs)
>  		return true;
> -	if (strlen(qs) != len)
> +	qs_len = strlen(qs);
> +	if (prefix ? qs_len > len : qs_len != len)
>  		return false;
> -	return !strncmp(qs, str, len);
> +	return !strncmp(qs, str, qs_len);
>  }

The variable naming qs_len and the "if(<ternary operator>)" aren't very easy
to process. It's correct but could use a few comments to explain that for
prefix match, we only compare up to the PN/Vendor string length.

But there's already a good comment on the macro definition, I'm personally
OK with this.

>  
>  static const struct sfp_quirk *sfp_lookup_quirk(const struct sfp_eeprom_id *id)
> @@ -645,8 +655,10 @@ static const struct sfp_quirk *sfp_lookup_quirk(const struct sfp_eeprom_id *id)
>  	ps = sfp_strlen(id->base.vendor_pn, ARRAY_SIZE(id->base.vendor_pn));
>  
>  	for (i = 0, q = sfp_quirks; i < ARRAY_SIZE(sfp_quirks); i++, q++)
> -		if (sfp_match(q->vendor, id->base.vendor_name, vs) &&
> -		    sfp_match(q->part, id->base.vendor_pn, ps))
> +		if (sfp_match(q->vendor, id->base.vendor_name, vs,
> +			      q->prefix_match) &&
> +		    sfp_match(q->part, id->base.vendor_pn, ps,
> +			      q->prefix_match))
>  			return q;
>  
>  	return NULL;
> diff --git a/drivers/net/phy/sfp.h b/drivers/net/phy/sfp.h
> index 879dff7..867e45e 100644
> --- a/drivers/net/phy/sfp.h
> +++ b/drivers/net/phy/sfp.h
> @@ -12,6 +12,7 @@ struct sfp_quirk {
>  	void (*support)(const struct sfp_eeprom_id *id,
>  			struct sfp_module_caps *caps);
>  	void (*fixup)(struct sfp *sfp);
> +	bool prefix_match;
>  };
>  
>  struct sfp_socket_ops {

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>

Maxime

[PATCH net-next 2/2] net: sfp: add quirks for OEM XGSPONST2001 and FS XGS-SFP-ONT-MACI

[Martino Dell'Ambrogio]

Cheap XGS-PON ONT sticks identifying as vendor "OEM", PN "XGSPONST2001"
have broken TX_FAULT and LOS indicators (driven by the ONU serial
passthrough wires) and need a longer T_START_UP than the SFF-8472
default. The Fiberstore XGS-SFP-ONT-MACI MAC-mode ONT stick has the
same ONT-class TX_FAULT/LOS wiring and startup behaviour. Apply the
existing sfp_fixup_potron handler to both, which masks both signals
and bumps T_START_UP to T_START_UP_BAD_GPON.

Both modules fail to space-pad the EEPROM vendor PN field past the
legitimate string as SFF-8472 mandates (the XGSPONST2001 fills it with
non-printable garbage), which defeats exact-length matching:
sfp_strlen() cannot trim the field, so a plain SFP_QUIRK_F entry would
silently never apply and the kernel would honor the spurious TX_FAULT
and eventually disable the module. Match both entries as prefixes
using SFP_QUIRK_F_PREFIX.

Signed-off-by: Martino Dell'Ambrogio <tillo@tillo.ch>
---
 drivers/net/phy/sfp.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
index e7ba642..eae0699 100644
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -555,6 +555,13 @@ static const struct sfp_quirk sfp_quirks[] = {
 	SFP_QUIRK("FS", "GPON-ONU-34-20BI", sfp_quirk_2500basex,
 		  sfp_fixup_ignore_tx_fault),
 
+	// Fiberstore XGS-SFP-ONT-MACI is a MAC-mode XGS-PON ONT stick with
+	// ONT-class serial-passthrough TX_FAULT/LOS wiring and slow startup;
+	// mask both signals and extend T_START_UP via the potron fixup. The
+	// EEPROM vendor PN field is not space-padded past the legitimate
+	// string, so match it as a prefix.
+	SFP_QUIRK_F_PREFIX("FS", "XGS-SFP-ONT-MACI", sfp_fixup_potron),
+
 	SFP_QUIRK_F("HALNy", "HL-GSFP", sfp_fixup_halny_gsfp),
 
 	SFP_QUIRK_F("H-COM", "SPP425H-GAB4", sfp_fixup_potron),
@@ -612,6 +619,14 @@ static const struct sfp_quirk sfp_quirks[] = {
 	SFP_QUIRK_S("OEM", "SFP-2.5G-LH20-A", sfp_quirk_2500basex),
 	SFP_QUIRK_F("OEM", "RTSFP-10", sfp_fixup_rollball_cc),
 	SFP_QUIRK_F("OEM", "RTSFP-10G", sfp_fixup_rollball_cc),
+
+	// OEM XGSPONST2001 is an XGS-PON ONT stick with broken TX_FAULT and
+	// LOS indicators and slow startup, just like potron. The EEPROM
+	// vendor PN field is filled with non-printable garbage past the
+	// legitimate string instead of space padding, so match it as a
+	// prefix.
+	SFP_QUIRK_F_PREFIX("OEM", "XGSPONST2001", sfp_fixup_potron),
+
 	SFP_QUIRK_F("Turris", "RTSFP-2.5G", sfp_fixup_rollball),
 	SFP_QUIRK_F("Turris", "RTSFP-10", sfp_fixup_rollball),
 	SFP_QUIRK_F("Turris", "RTSFP-10G", sfp_fixup_rollball),
-- 
2.47.3

Re: [PATCH net-next 2/2] net: sfp: add quirks for OEM XGSPONST2001 and FS XGS-SFP-ONT-MACI

[Maxime Chevallier]

Hi

On 7/5/26 20:54, Martino Dell'Ambrogio wrote:
> Cheap XGS-PON ONT sticks identifying as vendor "OEM", PN "XGSPONST2001"
> have broken TX_FAULT and LOS indicators (driven by the ONU serial
> passthrough wires) and need a longer T_START_UP than the SFF-8472
> default. The Fiberstore XGS-SFP-ONT-MACI MAC-mode ONT stick has the
> same ONT-class TX_FAULT/LOS wiring and startup behaviour. Apply the
> existing sfp_fixup_potron handler to both, which masks both signals
> and bumps T_START_UP to T_START_UP_BAD_GPON.
> 
> Both modules fail to space-pad the EEPROM vendor PN field past the
> legitimate string as SFF-8472 mandates (the XGSPONST2001 fills it with
> non-printable garbage), which defeats exact-length matching:
> sfp_strlen() cannot trim the field, so a plain SFP_QUIRK_F entry would
> silently never apply and the kernel would honor the spurious TX_FAULT
> and eventually disable the module. Match both entries as prefixes
> using SFP_QUIRK_F_PREFIX.
> 
> Signed-off-by: Martino Dell'Ambrogio <tillo@tillo.ch>

Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>

Maxime

Re: [PATCH net-next 0/2] net: sfp: quirk support for XGS-PON ONT sticks with unclean EEPROMs

[Jakub Kicinski]

On Sun,  5 Jul 2026 20:54:37 +0200 Martino Dell'Ambrogio wrote:
> Some clone XGS-PON ONT sticks ship EEPROMs where the vendor PN field is
> filled with non-printable garbage past the legitimate string instead of
> the SFF-8472 mandated space padding. sfp_strlen() then can't trim the
> field, the exact-length check in sfp_match() rejects the quirk entry
> before the string comparison runs, and the quirk silently never applies
> — so the kernel honors the module's spurious TX_FAULT and eventually
> disables it.

The netdev patch queue has overflown.
If these patches are still relevant you'll have to repost them.