netdev - RE: [net-next 01/13] e1000e: Fix no connectivity when driver loaded with cable out

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Date:	Fri, 18 Apr 2014 15:27:47 +0000
From:	"Ertman, DavidX M" <davidx.m.ertman@...el.com>
To:	Ben Hutchings <ben@...adent.org.uk>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>
CC:	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"gospo@...hat.com" <gospo@...hat.com>,
	"sassmann@...hat.com" <sassmann@...hat.com>
Subject: RE: [net-next 01/13] e1000e: Fix no connectivity when driver loaded
 with cable out

> -----Original Message-----
> From: Ben Hutchings [mailto:ben@...adent.org.uk]
> Sent: Friday, April 18, 2014 6:16 AM
> To: Kirsher, Jeffrey T; Ertman, DavidX M
> Cc: davem@...emloft.net; netdev@...r.kernel.org; gospo@...hat.com;
> sassmann@...hat.com
> Subject: Re: [net-next 01/13] e1000e: Fix no connectivity when driver loaded
> with cable out
> 
> On Mon, 2014-03-31 at 16:34 -0700, Jeff Kirsher wrote:
> > From: David Ertman <davidx.m.ertman@...el.com>
> >
> > In commit da1e2046e5, the flow for enabling/disabling an Si errata
> > workaround (e1000_lv_jumbo_workaround_ich8lan) was changed to fix a
> problem
> > with iAMT connections dropping on interface down with jumbo frames set.
> > Part of this change was to move the function call disabling the workaround
> > to e1000e_down() from the e1000_setup_rctl() function.  The mechanic for
> > disabling of this workaround involves writing several MAC and PHY registers
> > back to hardware defaults.
> >
> > After this commit, when the driver is loaded with the cable out, the PHY
> > registers are not programmed with the correct default values.  This causes
> > the device to be capable of transmitting packets, but is unable to recieve
> > them until this workaround is called.
> [...]
> 
> Which devices are affected by this?  I just did a backport of e1000e
> from 3.13 for Debian 7.5 and didn't spot this fix until later.
> 
> I couldn't reproduce this problem on my laptop, which has:
> 
> 00:19.0 Ethernet controller [0200]: Intel Corporation 82579LM Gigabit
> Network Connection [8086:1502] (rev 04)
> 
> Ben.
> 
> --
> Ben Hutchings
> Lowery's Law:
>              If it jams, force it. If it breaks, it needed replacing anyway.

i217 parts are affected by this issue.

It is possible that 82579 parts are not affected (I don't think a repro was done with one of these devices), but the code involved was originally put in for an 82579 workaround.

Dave Ertman