[Intel-wired-lan] [PATCH] ixgbe: Check DDM existence in transceiver before access

[Jesse Brandeburg]

On Thu, 23 May 2019 16:11:12 -0300 Mauro wrote:
> 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 at linux.vnet.ibm.com>

Looks reasonable, thanks for the patch!

Reviewed-by: Jesse Brandeburg <jesse.brandeburg at intel.com>