netdev - RE: [PATCH net 1/4] lan78xx: Fix for crash associated with System suspend

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Message-ID: <CE371C1263339941885964188A0225FA3335B8@CHN-SV-EXMX03.mchp-main.com>
Date:   Wed, 6 Sep 2017 17:34:48 +0000
From:   <Nisar.Sayed@...rochip.com>
To:     <andrew@...n.ch>
CC:     <davem@...emloft.net>, <UNGLinuxDriver@...rochip.com>,
        <netdev@...r.kernel.org>
Subject: RE: [PATCH net 1/4] lan78xx: Fix for crash associated with System
 suspend

Thanks Andrew inputs.
 
> On Wed, Sep 06, 2017 at 10:51:31AM +0000, Nisar.Sayed@...rochip.com
> wrote:
> > From: Nisar Sayed <Nisar.Sayed@...rochip.com>
> >
> > Fix for crash associated with System suspend
> >
> > Since ndo_stop removes phydev which makes phydev NULL.
> > Whenever system suspend is initiated or after "ifconfig <interface>
> > down", if set_wol or get_wol is triggered phydev is NULL leads system
> crash.
> > Hence phy_start/phy_stop for ndo_start/ndo_stop fixes the issues
> > instead of adding/removing phydevice
> 
> Looking at this patch, there apears to be lots of different things going on.
> Please can you split it up into multiple patches.

Sure will split it up.

> 
> > Signed-off-by: Nisar Sayed <Nisar.Sayed@...rochip.com>
> > ---
> >  drivers/net/usb/lan78xx.c | 44
> > ++++++++++++++++++++++++++++----------------
> >  1 file changed, 28 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/net/usb/lan78xx.c b/drivers/net/usb/lan78xx.c
> > index b99a7fb..955ab3b 100644
> > --- a/drivers/net/usb/lan78xx.c
> > +++ b/drivers/net/usb/lan78xx.c
> > @@ -2024,6 +2024,8 @@ static int lan78xx_phy_init(struct lan78xx_net
> *dev)
> >  						 lan8835_fixup);
> >  		if (ret < 0) {
> >  			netdev_err(dev->net, "fail to register fixup\n");
> > +			phy_unregister_fixup_for_uid(PHY_KSZ9031RNX,
> > +						     0xfffffff0);
> 
> goto error; would be better. phy_unregister_fixup_for_uid() does not care if
> you try to unregister something which has not been registered.
> 
> Also, this should be a separate patch.

Ok, will make it as separate patch

> 
> >  			return ret;
> >  		}
> >  		/* add more external PHY fixup here if needed */ @@ -
> 2031,8 +2033,7
> > @@ static int lan78xx_phy_init(struct lan78xx_net *dev)
> >  		phydev->is_internal = false;
> >  	} else {
> >  		netdev_err(dev->net, "unknown ID found\n");
> > -		ret = -EIO;
> > -		goto error;
> > +		return -EIO;
> >  	}
> >
> >  	/* if phyirq is not set, use polling mode in phylib */ @@ -2051,7
> > +2052,10 @@ static int lan78xx_phy_init(struct lan78xx_net *dev)
> >  	if (ret) {
> >  		netdev_err(dev->net, "can't attach PHY to %s\n",
> >  			   dev->mdiobus->id);
> > -		return -EIO;
> > +		ret = -EIO;
> > +		if (dev->chipid == ID_REV_CHIP_ID_7801_)
> > +			goto error;
> > +		return ret;
> 
> Why not add the if (dev->chipid == ID_REV_CHIP_ID_7801_) after the
> error: label?
> 
> 


Yes, will correct it

> 
> >  	}
> >
> >  	/* MAC doesn't support 1000T Half */ @@ -2067,8 +2071,6 @@ static
> > int lan78xx_phy_init(struct lan78xx_net *dev)
> >
> >  	dev->fc_autoneg = phydev->autoneg;
> >
> > -	phy_start(phydev);
> > -
> >  	netif_dbg(dev, ifup, dev->net, "phy initialised successfully");
> >
> >  	return 0;
> > @@ -2497,9 +2499,9 @@ static int lan78xx_open(struct net_device *net)
> >  	if (ret < 0)
> >  		goto done;
> >
> > -	ret = lan78xx_phy_init(dev);
> > -	if (ret < 0)
> > -		goto done;
> > +	if (dev->domain_data.phyirq > 0)
> > +		phy_start_interrupts(dev->net->phydev);
> 
> This is unusual. I don't see any other MAC driver starting interrupts.
> This needs explaining.
> 
>      Andrew

Since "lan78xx_open" calls  "lan78xx_reset" (Device reset) it is required to start/enable interrupt back
Initially when "phydev->state = PHY_READY" state  "phy_start" will not enable interrupts,
However after "lan78xx_stop" when "phy_stop" makes "phydev->state = PHY_HALTED"
Subsequent call to "phy_start" will enable interrupt.

Hence "phy_start_interrupts" used after "lan78xx_reset"

- Nisar