Subject: Re: [PATCH v3] net: sfp: handle 100G/25G active optical cables in sfp_parse_support

From: "Russell King (Oracle)" <[email-masked]>
Date: Fri, 18 Aug 2023 12:37:27 +0100

On Fri, Aug 18, 2023 at 01:05:56PM +0200, Josua Mayer wrote:
> Handle extended compliance code 0x1 (SFF8024_ECC_100G_25GAUI_C2M_AOC)
> for active optical cables supporting 25G and 100G speeds.
> 
> Since the specification makes no statement about transmitter range, and
> as the specific sfp module that had been tested features only 2m fiber -
> short-range (SR) modes are selected.
> 
> The 100G speed is irrelevant because it would require multiple fibers /
> multiple SFP28 modules combined under one netdev.
> sfp-bus.c only handles a single module per netdev, so only 25Gbps modes
> are selected.
> 
> sfp_parse_support already handles SFF8024_ECC_100GBASE_SR4_25GBASE_SR
> with compatible properties, however that entry is a contradiction in
> itself since with SFP(28) 100GBASE_SR4 is impossible - that would likely
> be a mode for qsfp modules only.
> 
> Add a case for SFF8024_ECC_100G_25GAUI_C2M_AOC selecting 25gbase-r
> interface mode and 25000baseSR link mode.
> Also enforce SFP28 bitrate limits on the values read from sfp eeprom as
> requested by Russell King.
> 
> Tested with fs.com S28-AO02 AOC SFP28 module.
> 
> Signed-off-by: Josua Mayer <[email-masked]>

Reviewed-by: Russell King (Oracle) <[email-masked]>

Thanks!

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!