ixgbe: Check DDM existence in transceiver before access

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Some transceivers may comply with SFF-8472 but not implement the Digital
Diagnostic Monitoring (DDM) interface described in it. The existence of
such area is specified by bit 6 of byte 92, set to 1 if implemented.

Currently, due to not checking this bit ixgbe fails trying to read SFP
module's eeprom with the follow message:

ethtool -m enP51p1s0f0
Cannot get Module EEPROM data: Input/output error

Because it fails to read the additional 256 bytes in which it was assumed
to exist the DDM data.

This issue was noticed using a Mellanox Passive DAC PN 01FT738. The eeprom
data was confirmed by Mellanox as correct and present in other Passive
DACs in from other manufacturers.

Signed-off-by: "Mauro S. M. Rodrigues" <maurosr@linux.vnet.ibm.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

...

This commit is contained in:

Mauro S. M. Rodrigues 2019-05-23 16:11:12 -03:00 • committed by Jeff Kirsher

parent 3b52569152

commit 655c914145

2 changed files with 3 additions and 1 deletions

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3

drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c

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1

drivers/net/ethernet/intel/ixgbe/ixgbe_phy.h

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