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[RFC] net: phy: smsc: Disable auto-negotiation on startup

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  [RFC] net: phy: smsc: Disable auto-negotiation on startup Kyle Roeschley <kyle.roeschley@ni.com> - 2016-10-10 19:50 +0200
    Re: [RFC] net: phy: smsc: Disable auto-negotiation on startup Jeremy Linton <jeremy.linton@arm.com> - 2016-10-11 16:40 +0200
    Re: [RFC] net: phy: smsc: Disable auto-negotiation on startup Florian Fainelli <f.fainelli@gmail.com> - 2016-10-12 11:40 +0200
      Re: [RFC] net: phy: smsc: Disable auto-negotiation on startup Andrew Lunn <andrew@lunn.ch> - 2016-10-12 22:30 +0200

#1498455 — [RFC] net: phy: smsc: Disable auto-negotiation on startup

Because the SMSC PHY completes auto-negotiation before the driver is
ready to handle interrupts, the PHY state machine never realizes that we
have a link. Clear the ANENABLE bit on initialization, which lets
genphy_config_aneg do its thing when that code is hit later.

While this patch does fix the problem we see (no link on boot without
re-plugging the cable), it seems like the generic PHY code should be
able to handle auto-negotiation completing before interrupts are
enabled. Submitted as an RFC in the hopes that someone has an idea as to
how that could be done.

This fix is copied from commit 99f81afc139c ("phy: micrel: Disable auto
negotiation on startup").

Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
---
 drivers/net/phy/smsc.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/net/phy/smsc.c b/drivers/net/phy/smsc.c
index b62c4aa..8de8011 100644
--- a/drivers/net/phy/smsc.c
+++ b/drivers/net/phy/smsc.c
@@ -62,6 +62,16 @@ static int smsc_phy_config_init(struct phy_device *phydev)
 			return rc;
 	}
 
+	if (phy_interrupt_is_valid(phydev)) {
+		rc = phy_read(phydev, MII_BMCR);
+		if (rc < 0)
+			return rc;
+
+		rc = phy_write(phydev, MII_BMCR, rc & ~BMCR_ANENABLE);
+		if (rc < 0)
+			return rc;
+	}
+
 	return smsc_phy_ack_interrupt(phydev);
 }
 
-- 
2.9.3

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#1498929

On 10/10/2016 12:41 PM, Kyle Roeschley wrote:
> Because the SMSC PHY completes auto-negotiation before the driver is
> ready to handle interrupts, the PHY state machine never realizes that we
> have a link. Clear the ANENABLE bit on initialization, which lets
> genphy_config_aneg do its thing when that code is hit later.
>
> While this patch does fix the problem we see (no link on boot without
> re-plugging the cable), it seems like the generic PHY code should be
> able to handle auto-negotiation completing before interrupts are
> enabled. Submitted as an RFC in the hopes that someone has an idea as to
> how that could be done.

Hi,

	Which smsc chip/driver? Maybe assuring the device interrupts are 
enabled before the phy is started is a solution?

	The whole problem sounds similar to what was recently happening in the 
smsc911x driver, but AFAIK that driver is basically only polling at this 
point so connecting the phy before the interrupts are enabled shouldn't 
be a problem.




>
> This fix is copied from commit 99f81afc139c ("phy: micrel: Disable auto
> negotiation on startup").
>
> Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
> ---
>  drivers/net/phy/smsc.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/drivers/net/phy/smsc.c b/drivers/net/phy/smsc.c
> index b62c4aa..8de8011 100644
> --- a/drivers/net/phy/smsc.c
> +++ b/drivers/net/phy/smsc.c
> @@ -62,6 +62,16 @@ static int smsc_phy_config_init(struct phy_device *phydev)
>  			return rc;
>  	}
>
> +	if (phy_interrupt_is_valid(phydev)) {
> +		rc = phy_read(phydev, MII_BMCR);
> +		if (rc < 0)
> +			return rc;
> +
> +		rc = phy_write(phydev, MII_BMCR, rc & ~BMCR_ANENABLE);
> +		if (rc < 0)
> +			return rc;
> +	}
> +
>  	return smsc_phy_ack_interrupt(phydev);
>  }
>
>

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#1499449

On 10/10/2016 10:41 AM, Kyle Roeschley wrote:
> Because the SMSC PHY completes auto-negotiation before the driver is
> ready to handle interrupts, the PHY state machine never realizes that we
> have a link. Clear the ANENABLE bit on initialization, which lets
> genphy_config_aneg do its thing when that code is hit later.
> 
> While this patch does fix the problem we see (no link on boot without
> re-plugging the cable), it seems like the generic PHY code should be
> able to handle auto-negotiation completing before interrupts are
> enabled. Submitted as an RFC in the hopes that someone has an idea as to
> how that could be done.
> 
> This fix is copied from commit 99f81afc139c ("phy: micrel: Disable auto
> negotiation on startup").

Do you mind trying:

https://www.spinics.net/lists/netdev/msg397857.html

and see if you do get link interrupts without your patch applied? Thanks!
-- 
Florian

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#1499913

On Wed, Oct 12, 2016 at 10:05:33AM -0500, Kyle Roeschley wrote:
> On Wed, Oct 12, 2016 at 02:13:06AM -0700, Florian Fainelli wrote:
> > On 10/10/2016 10:41 AM, Kyle Roeschley wrote:
> > > Because the SMSC PHY completes auto-negotiation before the driver is
> > > ready to handle interrupts, the PHY state machine never realizes that we
> > > have a link. Clear the ANENABLE bit on initialization, which lets
> > > genphy_config_aneg do its thing when that code is hit later.
> > > 
> > > While this patch does fix the problem we see (no link on boot without
> > > re-plugging the cable), it seems like the generic PHY code should be
> > > able to handle auto-negotiation completing before interrupts are
> > > enabled. Submitted as an RFC in the hopes that someone has an idea as to
> > > how that could be done.
> > > 
> > > This fix is copied from commit 99f81afc139c ("phy: micrel: Disable auto
> > > negotiation on startup").
> > 
> > Do you mind trying:
> > 
> > https://www.spinics.net/lists/netdev/msg397857.html
> > 
> > and see if you do get link interrupts without your patch applied? Thanks!
> 
> Yep, that fixes it. I figured there was some state machine issue I was missing.
> Thanks very much!

Humm, O.K, time to pull that patch out of the series and make it
standalone.

	Andrew

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