netdev - Re: [PATCH] net: phy: fix auto-negotiation stall due to unavailable interrupt

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Date:   Wed, 19 Apr 2017 17:05:53 +0300
From:   Alexander Kochetkov <al.kochet@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: phy: fix auto-negotiation stall due to unavailable interrupt

Just found similar problem fixed in another PHY. See commit 99f81afc139c
("phy: micrel: Disable auto negotiation on startup»)

> 19 апр. 2017 г., в 16:46, Alexander Kochetkov <al.kochet@...il.com> написал(а):
> 
> The problem I fix related to SMSC LAN8710/LAN8720 PHY handled using
> interrupts. During power-up cycle the PHY do auto-negotiation, generate
> interrupt and set BMSR_ANEGCOMPLETE flag. Interrupt is handled by PHY
> state machine but doesn't update link because PHY is in PHY_READY state.
> After some time MAC bring up and connect with PHY. It start PHY using
> phy_start(). During startup PHY change state to PHY_AN but doesn't
> set BMCR_ANRESTART flag due to genphy_config_aneg() doesn't update MII_BMCR
> because there no new to advertising. As a result, state machine wait for
> interrupt from PHY and nether get "link is up". Because BMSR_ANEGCOMPLETE
> already set the patch schedule check link without waiting interrupt.
> In case genphy_config_aneg() update MII_BMCR and set BMCR_ANRESTART
> flag, BMSR_ANEGCOMPLETE will be cleared and state machine will continue
> on auto-negotiation interrupt.
> 
> Signed-off-by: Alexander Kochetkov <al.kochet@...il.com>
> ---
> drivers/net/phy/phy.c |   12 ++++++++++++
> 1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index 7cc1b7d..da8f03d 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -1169,6 +1169,18 @@ void phy_state_machine(struct work_struct *work)
> 	if (phydev->irq == PHY_POLL)
> 		queue_delayed_work(system_power_efficient_wq, &phydev->state_queue,
> 				   PHY_STATE_TIME * HZ);
> +
> +	/* Re-schedule a PHY state machine to check PHY status because
> +	 * negotiation already done and aneg interrupt may not be generated.
> +	 */
> +	if (needs_aneg && (phydev->irq > 0) && (phydev->state == PHY_AN)) {
> +		err = phy_aneg_done(phydev);
> +		if (err > 0)
> +			queue_delayed_work(system_power_efficient_wq,
> +					   &phydev->state_queue, 0);
> +		if (err < 0)
> +			phy_error(phydev);
> +	}
> }
> 
> /**
> -- 
> 1.7.9.5
>