netdev - Re: [PATCH] e1000e: workaround missing power down mii control bit on 82571

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Date:	Thu, 16 Dec 2010 18:56:37 +0000
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Arthur Jones <ajones@...erbed.com>
Cc:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>, netdev@...r.kernel.org
Subject: Re: [PATCH] e1000e: workaround missing power down mii control bit
 on 82571

On Thu, 2010-12-16 at 10:28 -0800, Arthur Jones wrote:
> Hi Jeff,  Re-sending w/ proper netdev email
> address.  Sorry about that...
> 
> Arthur
> 
> ---
> 
> On 82571 only, AFAICT, the PHY does not seem to
> store the MII control register 0 bit 11 (power
> down PHY). So that when we power down the PHY
> on dev_close() and then run ethtool on the closed
> dev, we end up turning the PHY back on even though
> the interface is down.  This pretty easy to repro:
> 
> $ ethtool -s eth0 wol d
> $ ifconfig eth0 up
> $ mii-tool eth0
> eth0: negotiated 100baseTx-FD, link ok
> $ ifconfig eth0 down
> $ mii-tool eth0
> eth0: no link
> $ ethtool -s eth0 autoneg on  (doesn't really matter what we do here)
> $ mii-tool eth0
> eth0: negotiated 100baseTx-FD, link ok (this should be: eth0: no link)
> 
> We fix this by tracking the power down bit that we
> write to the PHY control register and re-inserting
> it when we read it.
[...]

Adding this special case into MDIO access seems like a really nasty
hack.  Surely the callers that set the control register should take care
of this.

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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