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

[Bowers, AndrewX]

> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces at osuosl.org] On
> Behalf Of Mauro S. M. Rodrigues
> Sent: Thursday, May 23, 2019 12:11 PM
> To: intel-wired-lan at lists.osuosl.org; Kirsher, Jeffrey T
> <jeffrey.t.kirsher at intel.com>
> Cc: gromero at linux.vnet.ibm.com
> Subject: [Intel-wired-lan] [PATCH] ixgbe: Check DDM existence in transceiver
> before access
> 
> 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>
> ---
>  drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c | 3 ++-
>  drivers/net/ethernet/intel/ixgbe/ixgbe_phy.h     | 1 +
>  2 files changed, 3 insertions(+), 1 deletion(-)

Tested-by: Andrew Bowers <andrewx.bowers at intel.com>