Date:   Sat, 18 Mar 2023 10:31:48 -0400
From:   Sean Anderson <seanga2@...il.com>
To:     Simon Horman <simon.horman@...igine.com>
Cc:     "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 net-next v3 1/9] net: sunhme: Just restart autonegotiation
 if we can't bring the link up

On 3/18/23 04:37, Simon Horman wrote:
> On Mon, Mar 13, 2023 at 08:36:05PM -0400, Sean Anderson wrote:
>> If we've tried regular autonegotiation and forcing the link mode, just
>> restart autonegotiation instead of reinitializing the whole NIC.
>>
>> Signed-off-by: Sean Anderson <seanga2@...il.com>
> 
> ...
> 
>> @@ -606,6 +604,124 @@ static int is_lucent_phy(struct happy_meal *hp)
>>   	return ret;
>>   }
>>   
>> +/* hp->happy_lock must be held */
>> +static void
>> +happy_meal_begin_auto_negotiation(struct happy_meal *hp,
>> +				  void __iomem *tregs,
>> +				  const struct ethtool_link_ksettings *ep)
>> +{
>> +	int timeout;
>> +
>> +	/* Read all of the registers we are interested in now. */
>> +	hp->sw_bmsr      = happy_meal_tcvr_read(hp, tregs, MII_BMSR);
>> +	hp->sw_bmcr      = happy_meal_tcvr_read(hp, tregs, MII_BMCR);
>> +	hp->sw_physid1   = happy_meal_tcvr_read(hp, tregs, MII_PHYSID1);
>> +	hp->sw_physid2   = happy_meal_tcvr_read(hp, tregs, MII_PHYSID2);
>> +
>> +	/* XXX Check BMSR_ANEGCAPABLE, should not be necessary though. */
>> +
>> +	hp->sw_advertise = happy_meal_tcvr_read(hp, tregs, MII_ADVERTISE);
>> +	if (!ep || ep->base.autoneg == AUTONEG_ENABLE) {
>> +		/* Advertise everything we can support. */
>> +		if (hp->sw_bmsr & BMSR_10HALF)
>> +			hp->sw_advertise |= (ADVERTISE_10HALF);
>> +		else
>> +			hp->sw_advertise &= ~(ADVERTISE_10HALF);
>> +
>> +		if (hp->sw_bmsr & BMSR_10FULL)
>> +			hp->sw_advertise |= (ADVERTISE_10FULL);
>> +		else
>> +			hp->sw_advertise &= ~(ADVERTISE_10FULL);
>> +		if (hp->sw_bmsr & BMSR_100HALF)
>> +			hp->sw_advertise |= (ADVERTISE_100HALF);
>> +		else
>> +			hp->sw_advertise &= ~(ADVERTISE_100HALF);
>> +		if (hp->sw_bmsr & BMSR_100FULL)
>> +			hp->sw_advertise |= (ADVERTISE_100FULL);
>> +		else
>> +			hp->sw_advertise &= ~(ADVERTISE_100FULL);
>> +		happy_meal_tcvr_write(hp, tregs, MII_ADVERTISE, hp->sw_advertise);
>> +
>> +		/* XXX Currently no Happy Meal cards I know off support 100BaseT4,
>> +		 * XXX and this is because the DP83840 does not support it, changes
>> +		 * XXX would need to be made to the tx/rx logic in the driver as well
>> +		 * XXX so I completely skip checking for it in the BMSR for now.
>> +		 */
>> +
>> +		ASD("Advertising [ %s%s%s%s]\n",
>> +		    hp->sw_advertise & ADVERTISE_10HALF ? "10H " : "",
>> +		    hp->sw_advertise & ADVERTISE_10FULL ? "10F " : "",
>> +		    hp->sw_advertise & ADVERTISE_100HALF ? "100H " : "",
>> +		    hp->sw_advertise & ADVERTISE_100FULL ? "100F " : "");
>> +
>> +		/* Enable Auto-Negotiation, this is usually on already... */
>> +		hp->sw_bmcr |= BMCR_ANENABLE;
>> +		happy_meal_tcvr_write(hp, tregs, MII_BMCR, hp->sw_bmcr);
>> +
>> +		/* Restart it to make sure it is going. */
>> +		hp->sw_bmcr |= BMCR_ANRESTART;
>> +		happy_meal_tcvr_write(hp, tregs, MII_BMCR, hp->sw_bmcr);
>> +
>> +		/* BMCR_ANRESTART self clears when the process has begun. */
>> +
>> +		timeout = 64;  /* More than enough. */
>> +		while (--timeout) {
>> +			hp->sw_bmcr = happy_meal_tcvr_read(hp, tregs, MII_BMCR);
>> +			if (!(hp->sw_bmcr & BMCR_ANRESTART))
>> +				break; /* got it. */
>> +			udelay(10);
> 
> nit: Checkpatch tells me that usleep_range() is preferred over udelay().
>       Perhaps it would be worth looking into that for a follow-up patch.

This will be fixed in another series.

>> +		}
>> +		if (!timeout) {
>> +			netdev_err(hp->dev,
>> +				   "Happy Meal would not start auto negotiation BMCR=0x%04x\n",
>> +				   hp->sw_bmcr);
>> +			netdev_notice(hp->dev,
>> +				      "Performing force link detection.\n");
>> +			goto force_link;
>> +		} else {
>> +			hp->timer_state = arbwait;
>> +		}
>> +	} else {
>> +force_link:
>> +		/* Force the link up, trying first a particular mode.
>> +		 * Either we are here at the request of ethtool or
>> +		 * because the Happy Meal would not start to autoneg.
>> +		 */
>> +
>> +		/* Disable auto-negotiation in BMCR, enable the duplex and
>> +		 * speed setting, init the timer state machine, and fire it off.
>> +		 */
>> +		if (!ep || ep->base.autoneg == AUTONEG_ENABLE) {
>> +			hp->sw_bmcr = BMCR_SPEED100;
>> +		} else {
>> +			if (ep->base.speed == SPEED_100)
>> +				hp->sw_bmcr = BMCR_SPEED100;
>> +			else
>> +				hp->sw_bmcr = 0;
>> +			if (ep->base.duplex == DUPLEX_FULL)
>> +				hp->sw_bmcr |= BMCR_FULLDPLX;
>> +		}
>> +		happy_meal_tcvr_write(hp, tregs, MII_BMCR, hp->sw_bmcr);
>> +
>> +		if (!is_lucent_phy(hp)) {
>> +			/* OK, seems we need do disable the transceiver for the first
>> +			 * tick to make sure we get an accurate link state at the
>> +			 * second tick.
>> +			 */
>> +			hp->sw_csconfig = happy_meal_tcvr_read(hp, tregs,
>> +							       DP83840_CSCONFIG);
>> +			hp->sw_csconfig &= ~(CSCONFIG_TCVDISAB);
>> +			happy_meal_tcvr_write(hp, tregs, DP83840_CSCONFIG,
>> +					      hp->sw_csconfig);
>> +		}
>> +		hp->timer_state = ltrywait;
>> +	}
>> +
>> +	hp->timer_ticks = 0;
>> +	hp->happy_timer.expires = jiffies + (12 * HZ)/10;  /* 1.2 sec. */
> 
> nit: as a follow-up perhaps you could consider something like this.
>       (* completely untested! * )
> 
> 	hp->happy_timer.expires = jiffies + msecs_to_jiffies(1200);

ditto.

>> +	add_timer(&hp->happy_timer);
>> +}
>> +
> 
> ...

--Sean

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