linux-kernel - Re: [PATCH v2] net: sfp: Add tx-fault workaround for Huawei MA5671A SFP ONT

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Date:   Sun, 8 May 2022 18:19:39 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Matthew Hagan <mnhagan88@...il.com>
Cc:     Russell King <linux@...linux.org.uk>, Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] net: sfp: Add tx-fault workaround for Huawei MA5671A
 SFP ONT

On Sunday 08 May 2022 18:17:12 Pali Rohár wrote:
> On Monday 02 May 2022 23:33:15 Matthew Hagan wrote:
> > As noted elsewhere, various GPON SFP modules exhibit non-standard
> > TX-fault behaviour. In the tested case, the Huawei MA5671A, when used
> > in combination with a Marvell mv88e6085 switch, was found to
> > persistently assert TX-fault, resulting in the module being disabled.
> 
> Hello! I have some other GPON SFP modules with this issue... which has
> inverted TX-fault signal.

Anyway, I'm planning to send patches for fixing other GPON modules...

> > This patch adds a quirk to ignore the SFP_F_TX_FAULT state, allowing the
> > module to function.
> 
> I think that you should rather invert TX-fault signal, instead of
> masking it.
> 
> > Change from v1: removal of erroneous return statment (Andrew Lunn)
> > 
> > Signed-off-by: Matthew Hagan <mnhagan88@...il.com>
> > ---
> >  drivers/net/phy/sfp.c | 12 +++++++++++-
> >  1 file changed, 11 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
> > index 4dfb79807823..9a5d5a10560f 100644
> > --- a/drivers/net/phy/sfp.c
> > +++ b/drivers/net/phy/sfp.c
> > @@ -250,6 +250,7 @@ struct sfp {
> >  	struct sfp_eeprom_id id;
> >  	unsigned int module_power_mW;
> >  	unsigned int module_t_start_up;
> > +	bool tx_fault_ignore;
> >  
> >  #if IS_ENABLED(CONFIG_HWMON)
> >  	struct sfp_diag diag;
> > @@ -1956,6 +1957,12 @@ static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
> >  	else
> >  		sfp->module_t_start_up = T_START_UP;
> >  
> > +	if (!memcmp(id.base.vendor_name, "HUAWEI          ", 16) &&
> > +	    !memcmp(id.base.vendor_pn, "MA5671A         ", 16))
> > +		sfp->tx_fault_ignore = true;
> > +	else
> > +		sfp->tx_fault_ignore = false;
> > +
> >  	return 0;
> >  }
> >  
> > @@ -2409,7 +2416,10 @@ static void sfp_check_state(struct sfp *sfp)
> >  	mutex_lock(&sfp->st_mutex);
> >  	state = sfp_get_state(sfp);
> >  	changed = state ^ sfp->state;
> > -	changed &= SFP_F_PRESENT | SFP_F_LOS | SFP_F_TX_FAULT;
> > +	if (sfp->tx_fault_ignore)
> > +		changed &= SFP_F_PRESENT | SFP_F_LOS;
> > +	else
> > +		changed &= SFP_F_PRESENT | SFP_F_LOS | SFP_F_TX_FAULT;
> >  
> >  	for (i = 0; i < GPIO_MAX; i++)
> >  		if (changed & BIT(i))
> > -- 
> > 2.27.0
> >