From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Fri, 15 Dec 2017 16:09:41 +0000
Subject: sfp: fix EEPROM reading in the case of non-SFF8472 SFPs
Patch-mainline: v4.16-rc1
Git-commit: 2794ffc441dde3109804085dc745e8014a4de224
References: bsc#1119113 FATE#326472

The EEPROM reading was trying to read from the second EEPROM address
if we requested the last byte from the SFF8079 EEPROM, which caused a
failure when the second EEPROM is not present.  Discovered with a
S-RJ01 SFP module.  Fix this.

Fixes: 73970055450e ("sfp: add SFP module support")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/phy/sfp.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -664,20 +664,19 @@ static int sfp_module_eeprom(struct sfp
 		len = min_t(unsigned int, last, ETH_MODULE_SFF_8079_LEN);
 		len -= first;
 
-		ret = sfp->read(sfp, false, first, data, len);
+		ret = sfp_read(sfp, false, first, data, len);
 		if (ret < 0)
 			return ret;
 
 		first += len;
 		data += len;
 	}
-	if (first >= ETH_MODULE_SFF_8079_LEN &&
-	    first < ETH_MODULE_SFF_8472_LEN) {
+	if (first < ETH_MODULE_SFF_8472_LEN && last > ETH_MODULE_SFF_8079_LEN) {
 		len = min_t(unsigned int, last, ETH_MODULE_SFF_8472_LEN);
 		len -= first;
 		first -= ETH_MODULE_SFF_8079_LEN;
 
-		ret = sfp->read(sfp, true, first, data, len);
+		ret = sfp_read(sfp, true, first, data, len);
 		if (ret < 0)
 			return ret;
 	}