netdev - Re: [PATCH] Add ethtool to mii advertisment conversion helpers

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Date:	Thu, 17 Nov 2011 00:34:37 +0000
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Matt Carlson <mcarlson@...adcom.com>
CC:	<davem@...emloft.net>, <netdev@...r.kernel.org>,
	Michael Chan <mchan@...adcom.com>
Subject: Re: [PATCH] Add ethtool to mii advertisment conversion helpers

On Tue, 2011-11-15 at 14:00 -0800, Matt Carlson wrote:
> Translating between ethtool advertisement settings and MII
> advertisements are common operations for ethernet drivers.  This patch
> adds a set of helper functions that implements the conversion.  The
> patch then modifies a couple of the drivers to use the new functions.

I like this, but:

[....]
> --- a/drivers/net/ethernet/broadcom/tg3.c
> +++ b/drivers/net/ethernet/broadcom/tg3.c
[...]
> @@ -4903,23 +4880,19 @@ static int tg3_setup_fiber_mii_phy(struct tg3 *tp, int force_reset)
>  	    (tp->phy_flags & TG3_PHYFLG_PARALLEL_DETECT)) {
>  		/* do nothing, just check for link up at the end */
>  	} else if (tp->link_config.autoneg == AUTONEG_ENABLE) {
> -		u32 adv, new_adv;
> +		u32 adv, newadv;
>  
>  		err |= tg3_readphy(tp, MII_ADVERTISE, &adv);
> -		new_adv = adv & ~(ADVERTISE_1000XFULL | ADVERTISE_1000XHALF |
> -				  ADVERTISE_1000XPAUSE |
> -				  ADVERTISE_1000XPSE_ASYM |
> -				  ADVERTISE_SLCT);
> -
> -		new_adv |= tg3_advert_flowctrl_1000X(tp->link_config.flowctrl);
> +		newadv = adv & ~(ADVERTISE_1000XFULL | ADVERTISE_1000XHALF |
> +				 ADVERTISE_1000XPAUSE |
> +				 ADVERTISE_1000XPSE_ASYM |
> +				 ADVERTISE_SLCT);

Not sure why you're renaming the variable here.

> -		if (tp->link_config.advertising & ADVERTISED_1000baseT_Half)
> -			new_adv |= ADVERTISE_1000XHALF;
> -		if (tp->link_config.advertising & ADVERTISED_1000baseT_Full)
> -			new_adv |= ADVERTISE_1000XFULL;
> +		newadv |= tg3_advert_flowctrl_1000X(tp->link_config.flowctrl);
> +		newadv |= ethtool_adv_to_mii_1000X(tp->link_config.advertising);

Doesn't this generate flow control advertising flags twice?  Can the
link_config.flowctrl and link_config.advertising fields get out of
synch?

[...]
> --- a/include/linux/mii.h
> +++ b/include/linux/mii.h
> @@ -240,6 +240,171 @@ static inline unsigned int mii_duplex (unsigned int duplex_lock,
>  }
>  
>  /**
> + * ethtool_adv_to_mii_100bt
> + * @ethadv: the ethtool advertisement settings
> + *
> + * A small helper function that translates ethtool advertisement
> + * settings to phy autonegotiation advertisements for the
> + * MII_ADVERTISE register.
> + */
> +static inline u32 ethtool_adv_to_mii_100bt(u32 ethadv)
[...]
> +static inline u32 mii_adv_to_ethtool_100bt(u32 adv)
[...]
> +static inline u32 ethtool_adv_to_mii_1000T(u32 ethadv)
[...]
> +static inline u32 mii_adv_to_ethtool_1000T(u32 adv)
[...]
> +#define mii_lpa_to_ethtool_100bt(lpa)	mii_adv_to_ethtool_100bt(lpa)

Shouldn't this additionally translate LPA_LPACK into ADVERTISED_Autoneg?

[...]
> +static inline u32 mii_lpa_to_ethtool_1000T(u32 lpa)
[...]
> +static inline u32 ethtool_adv_to_mii_1000X(u32 ethadv)
[...]
> +static inline u32 mii_adv_to_ethtool_1000X(u32 adv)
[...]

I'm not convinced about the naming convention for these.  Would it not
make more sense to name them consistently by register name and signal
type:

ethtool_adv_to_mii_adv_t
mii_adv_to_ethtool_adv_t
ethtool_adv_to_mii_ctrl1000_t
mii_ctrl1000_to_ethtool_adv_t
mii_lpa_to_ethtool_lpa_t
mii_stat1000_to_ethtool_lpa_t
ethtool_adv_to_mii_adv_x
mii_adv_to_ethtool_adv_x

Shouldn't there be mii_lpa_to_ethtool_1000X (or
mii_lpa_to_ethtool_lpa_x)?

Finally, do these need to be inline?

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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