Re: [PATCH net-next v3 1/2] ethtool: provide UAPI for PHY Signal Quality Index (SQI)

[Oleksij Rempel <o.rempel@pengutronix.de>]

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On Wed, May 20, 2020 at 04:45:44PM +0200, Michal Kubecek wrote:
> On Wed, May 20, 2020 at 08:29:14AM +0200, Oleksij Rempel wrote:
> > Signal Quality Index is a mandatory value required by "OPEN Alliance
> > SIG" for the 100Base-T1 PHYs [1]. This indicator can be used for cable
> > integrity diagnostic and investigating other noise sources and
> > implement by at least two vendors: NXP[2] and TI[3].
> > 
> > [1] http://www.opensig.org/download/document/218/Advanced_PHY_features_for_automotive_Ethernet_V1.0.pdf
> > [2] https://www.nxp.com/docs/en/data-sheet/TJA1100.pdf
> > [3] https://www.ti.com/product/DP83TC811R-Q1
> > 
> > Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> > ---
> 
> This looks good to me, there is just one thing I'm not sure about:
> 
> > diff --git a/include/linux/phy.h b/include/linux/phy.h
> > index 59344db43fcb1..950ba479754bd 100644
> > --- a/include/linux/phy.h
> > +++ b/include/linux/phy.h
> > @@ -706,6 +706,8 @@ struct phy_driver {
> >  			    struct ethtool_tunable *tuna,
> >  			    const void *data);
> >  	int (*set_loopback)(struct phy_device *dev, bool enable);
> > +	int (*get_sqi)(struct phy_device *dev);
> > +	int (*get_sqi_max)(struct phy_device *dev);
> >  };
> >  #define to_phy_driver(d) container_of(to_mdio_common_driver(d),		\
> >  				      struct phy_driver, mdiodrv)
> 
> I'm not sure if it's a good idea to define two separate callbacks. It
> means adding two pointers instead of one (for every instance of the
> structure, not only those implementing them), doing two calls, running
> the same checks twice, locking twice, checking the result twice.
> 
> Also, passing a structure pointer would mean less code changed if we
> decide to add more related state values later.
> 
> What do you think?
> 
> If you don't agree, I have no objections so
> 
> Reviewed-by: Michal Kubecek <mkubecek@suse.cz>

I have no strong opinion on it. Should I rework it?


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