Re: [PATCH net-next] net: sfp: add quirk for ZYXEL PMG3000-D20B

[Andrew Lunn]

On Mon, Oct 26, 2026 at 02:57:57PM +0100, Martin Ostertag wrote:
> The ZYXEL PMG3000-D20B GPON SFP module reports LOS and TX_FAULT in a
> way that prevents the SFP state machine from initialising it. Its
> EEPROM also advertises autonegotiation support although the module does
> not implement it, and the module needs about 60 seconds before it is
> ready.
> 
> Ignore LOS and TX_FAULT, disable the advertised autonegotiation and use
> T_START_UP_BAD_GPON as the wait time before the module is assumed to be
> initialised.
> 
> Tested with a ZYXEL PMG3000-D20B in an SFP cage.
> 
> Signed-off-by: Martin Ostertag <martin.ostertag@xxxxxx>
> ---
>  drivers/net/phy/sfp.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
> index 85e57a1..578d4d8 100644
> --- a/drivers/net/phy/sfp.c
> +++ b/drivers/net/phy/sfp.c
> @@ -472,6 +472,18 @@ static void sfp_fixup_potron(struct sfp *sfp)
>  	sfp_fixup_ignore_hw(sfp, SFP_F_TX_FAULT | SFP_F_LOS);
>  }
>  
> +static void sfp_fixup_zyxel(struct sfp *sfp)
> +{
> +	/*
> +	 * The LOS and TX_FAULT signals are not usable on this module, so
> +	 * ignore them. It also needs about 60s to become ready. Use
> +	 * module_t_wait, as module_t_start_up is not evaluated when
> +	 * TX_FAULT is ignored.
> +	 */
> +	sfp_fixup_ignore_tx_fault_and_los(sfp);
> +	sfp->module_t_wait = T_START_UP_BAD_GPON;

The other quirks call sfp_fixup_long_startup(), rather than directly
setting sfp->module_t_start_up. Please add a similar one line
function, and add the comment about why module_t_start_up is not used
there.

    Andrew

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