Re: [PATCH net-next v2 1/2] net: phy: sfp: Add support for SMBus module access

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

On 2/25/25 13:04, Russell King (Oracle) wrote:
> On Tue, Feb 25, 2025 at 12:20:39PM +0100, Maxime Chevallier wrote:
>> The SFP module's eeprom and internals are accessible through an i2c bus.
>> However, all the i2c transfers that are performed are SMBus-style
>> transfers for read and write operations.
> 
> Note that there are SFPs that fail if you access them by byte - the
> 3FE46541AA locks the bus if you byte access the emulated EEPROM at
> 0x50, address 0x51. This is documented in sfp_sm_mod_probe().
> 
> So there's a very real reason for adding the warning - this module
> will not work!
> 

I had a look at sfp_sm_mod_probe, and from what I can tell the SFP that
I was having issues with should have been fixed by commit 426c6cbc409c
("net: sfp: add workaround for Realtek RTL8672 and RTL9601C chips"). I
re-tested without this series applied, and the SFP still worked. So I
guess I don't have an SFP module with the issue this series is trying to
address after all.

--Sean