[PATCH 4.14 31/77] sfp: fix EEPROM reading in the case of non-SFF8472 SFPs

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Russell King <rmk+ker...@armlinux.org.uk>


[ Upstream commit 2794ffc441dde3109804085dc745e8014a4de224 ]

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+ker...@armlinux.org.uk>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 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
@@ -667,20 +667,19 @@ 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;
        }