From b91853ae2adeed3facf078034737d16827682895 Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@suse.cz>
Date: Apr 20 2023 11:00:54 +0000
Subject: net: sfp: initialize sfp->i2c_block_size at sfp allocation

(bsc#1012628).

---

diff --git a/patches.kernel.org/6.2.12-106-net-sfp-initialize-sfp-i2c_block_size-at-sfp-a.patch b/patches.kernel.org/6.2.12-106-net-sfp-initialize-sfp-i2c_block_size-at-sfp-a.patch
new file mode 100644
index 0000000..a156efa
--- /dev/null
+++ b/patches.kernel.org/6.2.12-106-net-sfp-initialize-sfp-i2c_block_size-at-sfp-a.patch
@@ -0,0 +1,84 @@
+From: Ivan Bornyakov <i.bornyakov@metrotek.ru>
+Date: Thu, 6 Apr 2023 16:08:32 +0300
+Subject: [PATCH] net: sfp: initialize sfp->i2c_block_size at sfp allocation
+References: bsc#1012628
+Patch-mainline: 6.2.12
+Git-commit: 813c2dd78618f108fdcf9cd726ea90f081ee2881
+
+commit 813c2dd78618f108fdcf9cd726ea90f081ee2881 upstream.
+
+sfp->i2c_block_size is initialized at SFP module insertion in
+sfp_sm_mod_probe(). Because of that, if SFP module was never inserted
+since boot, sfp_read() call will lead to zero-length I2C read attempt,
+and not all I2C controllers are happy with zero-length reads.
+
+One way to issue sfp_read() on empty SFP cage is to execute ethtool -m.
+If SFP module was never plugged since boot, there will be a zero-length
+I2C read attempt.
+
+  # ethtool -m xge0
+  i2c i2c-3: adapter quirk: no zero length (addr 0x0050, size 0, read)
+  Cannot get Module EEPROM data: Operation not supported
+
+If SFP module was plugged then removed at least once,
+sfp->i2c_block_size will be initialized and ethtool -m will fail with
+different exit code and without I2C error
+
+  # ethtool -m xge0
+  Cannot get Module EEPROM data: Remote I/O error
+
+Fix this by initializing sfp->i2_block_size at struct sfp allocation
+stage so no wild sfp_read() could issue zero-length I2C read.
+
+Signed-off-by: Ivan Bornyakov <i.bornyakov@metrotek.ru>
+Fixes: 0d035bed2a4a ("net: sfp: VSOL V2801F / CarlitoxxPro CPGOS03-0490 v2.0 workaround")
+Cc: stable@vger.kernel.org
+Reviewed-by: Andrew Lunn <andrew@lunn.ch>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Signed-off-by: Jiri Slaby <jslaby@suse.cz>
+---
+ drivers/net/phy/sfp.c | 13 ++++++++-----
+ 1 file changed, 8 insertions(+), 5 deletions(-)
+
+diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
+index 83b99d95..b224800d 100644
+--- a/drivers/net/phy/sfp.c
++++ b/drivers/net/phy/sfp.c
+@@ -212,6 +212,12 @@ static const enum gpiod_flags gpio_flags[] = {
+ #define SFP_PHY_ADDR		22
+ #define SFP_PHY_ADDR_ROLLBALL	17
+ 
++/* SFP_EEPROM_BLOCK_SIZE is the size of data chunk to read the EEPROM
++ * at a time. Some SFP modules and also some Linux I2C drivers do not like
++ * reads longer than 16 bytes.
++ */
++#define SFP_EEPROM_BLOCK_SIZE	16
++
+ struct sff_data {
+ 	unsigned int gpios;
+ 	bool (*module_supported)(const struct sfp_eeprom_id *id);
+@@ -1927,11 +1933,7 @@ static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
+ 	u8 check;
+ 	int ret;
+ 
+-	/* Some SFP modules and also some Linux I2C drivers do not like reads
+-	 * longer than 16 bytes, so read the EEPROM in chunks of 16 bytes at
+-	 * a time.
+-	 */
+-	sfp->i2c_block_size = 16;
++	sfp->i2c_block_size = SFP_EEPROM_BLOCK_SIZE;
+ 
+ 	ret = sfp_read(sfp, false, 0, &id.base, sizeof(id.base));
+ 	if (ret < 0) {
+@@ -2614,6 +2616,7 @@ static struct sfp *sfp_alloc(struct device *dev)
+ 		return ERR_PTR(-ENOMEM);
+ 
+ 	sfp->dev = dev;
++	sfp->i2c_block_size = SFP_EEPROM_BLOCK_SIZE;
+ 
+ 	mutex_init(&sfp->sm_mutex);
+ 	mutex_init(&sfp->st_mutex);
+-- 
+2.35.3
+
diff --git a/series.conf b/series.conf
index c953f7a..0758213 100644
--- a/series.conf
+++ b/series.conf
@@ -2333,6 +2333,7 @@
 	patches.kernel.org/6.2.12-103-ksmbd-avoid-out-of-bounds-access-in-decode_pre.patch
 	patches.kernel.org/6.2.12-104-riscv-add-icache-flush-for-nommu-sigreturn-tra.patch
 	patches.kernel.org/6.2.12-105-HID-intel-ish-hid-Fix-kernel-panic-during-warm.patch
+	patches.kernel.org/6.2.12-106-net-sfp-initialize-sfp-i2c_block_size-at-sfp-a.patch
 
 	########################################################
 	# Build fixes that apply to the vanilla kernel too.