Re: [PATCH net-next 0/2] net: phy: sfp: Add single-byte SMBus SFP access

[Sean Anderson <sean.anderson@linux.dev>]

On 2/23/25 12:28, Maxime Chevallier wrote:
> Hi everyone,
> 
> Some PHYs such as the VSC8552 have embedded "Two-wire Interfaces" designed to
> access SFP modules downstream. These controllers are actually SMBus controllers
> that can only perform single-byte accesses for read and write.
> 
> This series adds support for accessing SFP modules through single-byte SMBus,
> which could be relevant for other setups.
> 
> The first patch deals with the SFP module access by itself, for addresses 0x50
> and 0x51.
> 
> The second patch allows accessing embedded PHYs within the module with single-byte
> SMBus, adding this in the mdio-i2c driver.
> 
> As raw i2c transfers are always more efficient, we make sure that the smbus accesses
> are only used if we really have no other choices.
> 
> This has been tested with the following modules (as reported upon module insertion)
> 
> Fiber modules :
> 
> 	UBNT             UF-MM-1G         rev      sn FT20051201212    dc 200512
> 	PROLABS          SFP-1GSXLC-T-C   rev A1   sn PR2109CA1080     dc 220607
> 	CISCOSOLIDOPTICS CWDM-SFP-1490    rev 1.0  sn SOSC49U0891      dc 181008
> 	CISCOSOLIDOPTICS CWDM-SFP-1470    rev 1.0  sn SOSC47U1175      dc 190620
> 	OEM              SFP-10G-SR       rev 02   sn CSSSRIC3174      dc 181201
> 	FINISAR CORP.    FTLF1217P2BTL-HA rev A    sn PA3A0L6          dc 230716
> 	OEM              ES8512-3LCD05    rev 10   sn ESC22SX296055    dc 220722
> 	SOURCEPHOTONICS  SPP10ESRCDFF     rev 10   sn E8G2017450       dc 140715
> 	CXR              SFP-STM1-MM-850  rev 0000 sn K719017031       dc 200720
> 
>  Copper modules
> 
> 	OEM              SFT-7000-RJ45-AL rev 11.0 sn EB1902240862     dc 190313
> 	FINISAR CORP.    FCLF8521P2BTL    rev A    sn P1KBAPD          dc 190508
> 	CHAMPION ONE     1000SFPT         rev -    sn     GBC59750     dc 19110401
> 
> DAC :
> 
> 	OEM              SFP-H10GB-CU1M   rev R    sn CSC200803140115  dc 200827
> 
> In all cases, read/write operations happened without errors, and the internal
> PHY (if any) was always properly detected and accessible
> 
> I haven't tested with any RollBall SFPs though, as I don't have any, and I don't
> have Copper modules with anything else than a Marvell 88e1111 inside. The support
> for the VSC8552 SMBus may follow at some point.
> 
> Thanks,
> 
> Maxime
> 
> Maxime Chevallier (2):
>   net: phy: sfp: Add support for SMBus module access
>   net: mdio: mdio-i2c: Add support for single-byte SMBus operations
> 
>  drivers/net/mdio/mdio-i2c.c | 79 ++++++++++++++++++++++++++++++++++++-
>  drivers/net/phy/sfp.c       | 65 +++++++++++++++++++++++++++---
>  2 files changed, 138 insertions(+), 6 deletions(-)
> 

For this series:

Tested-by: Sean Anderson <sean.anderson@linux.dev>

With a

FS               SFP-GB-GE-T      rev F    sn F2030222359      dc 200729

See [1] for the original "bug report." Note that as discussed later in
the thread, this is a Fiber Store (fs.com) module and not a Finisar one.

--Sean

[1] https://lore.kernel.org/netdev/55f6cec4-2497-45a4-cb1a-3edafa7d80d3@seco.com/