netdev - Re: [patch 1/6] forcedeth: power down phy when interface is down

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Message-ID: <20080828192114.GA31454@ajones-laptop.nbttech.com>
Date:	Thu, 28 Aug 2008 12:21:15 -0700
From:	Arthur Jones <ajones@...erbed.com>
To:	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
CC:	"jeff@...zik.org" <jeff@...zik.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"eswierk@...stra.com" <eswierk@...stra.com>,
	"aabdulla@...dia.com" <aabdulla@...dia.com>
Subject: Re: [patch 1/6] forcedeth: power down phy when interface is down

Hi,  I just ran across this patch.  Tested on a
Marvell 88E1121R (GigE PHY) and works great.  This
is a very important feature for me...

Thanks!

Arthur

On Thu, Jul 03, 2008 at 11:43:08PM -0700, akpm@...ux-foundation.org wrote:
> From: "Ed Swierk" <eswierk@...stra.com>
> 
> Bring the physical link down when the interface is down by placing the PHY
> in power-down state, unless WOL is enabled.  This mirrors the behavior of
> other drivers including e1000 and tg3.
> 
> Without the patch, ifconfig down leaves the physical link up, which confuses
> datacenter users who expect the link lights both on the NIC and the switch to
> go out when they bring an interface down.
> 
> Furthermore, even though the phy is powered on, autonegotiation stops working,
> so a normally gigabit link might suddenly become 100 Mbit half-duplex when the
> interface goes down, and become gigabit when it comes up again.
> 
> Ayaz said:
> 
>   I would not include this patch until further testing is performed.  NVIDIA
>   MCP chips use 3rd party PHY vendors.  By powering down the phy, it could
>   have adverse affects on certain phys.
> 
> Signed-off-by: Ed Swierk <eswierk@...stra.com>
> Cc: Jeff Garzik <jeff@...zik.org>
> Cc: Ayaz Abdulla <aabdulla@...dia.com>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> ---
> 
>  drivers/net/forcedeth.c |   12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff -puN drivers/net/forcedeth.c~forcedeth-power-down-phy-when-interface-is-down drivers/net/forcedeth.c
> --- a/drivers/net/forcedeth.c~forcedeth-power-down-phy-when-interface-is-down
> +++ a/drivers/net/forcedeth.c
> @@ -1375,9 +1375,9 @@ static int phy_init(struct net_device *d
>         /* some phys clear out pause advertisment on reset, set it back */
>         mii_rw(dev, np->phyaddr, MII_ADVERTISE, reg);
> 
> -       /* restart auto negotiation */
> +       /* restart auto negotiation, power down phy */
>         mii_control = mii_rw(dev, np->phyaddr, MII_BMCR, MII_READ);
> -       mii_control |= (BMCR_ANRESTART | BMCR_ANENABLE);
> +       mii_control |= (BMCR_ANRESTART | BMCR_ANENABLE | BMCR_PDOWN);
>         if (mii_rw(dev, np->phyaddr, MII_BMCR, mii_control)) {
>                 return PHY_ERROR;
>         }
> @@ -5101,6 +5101,10 @@ static int nv_open(struct net_device *de
> 
>         dprintk(KERN_DEBUG "nv_open: begin\n");
> 
> +       /* power up phy */
> +       mii_rw(dev, np->phyaddr, MII_BMCR,
> +              mii_rw(dev, np->phyaddr, MII_BMCR, MII_READ) & ~BMCR_PDOWN);
> +
>         /* erase previous misconfiguration */
>         if (np->driver_data & DEV_HAS_POWER_CNTRL)
>                 nv_mac_reset(dev);
> @@ -5294,6 +5298,10 @@ static int nv_close(struct net_device *d
>         if (np->wolenabled) {
>                 writel(NVREG_PFF_ALWAYS|NVREG_PFF_MYADDR, base + NvRegPacketFilterFlags);
>                 nv_start_rx(dev);
> +       } else {
> +               /* power down phy */
> +               mii_rw(dev, np->phyaddr, MII_BMCR,
> +                      mii_rw(dev, np->phyaddr, MII_BMCR, MII_READ)|BMCR_PDOWN);
>         }
> 
>         /* FIXME: power down nic */
> _
> --
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