linux-kernel - Re: [PATCH] smsc: RFC: Workaround for problems with lan8710 phy auto MDI-X

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Message-ID: <alpine.LNX.2.00.1211301622110.25639@pobox.suse.cz>
Date:	Fri, 30 Nov 2012 16:23:30 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Peter Turczak <pt@...consequence.de>
Cc:	David Miller <davem@...emloft.net>,
	Otavio Salvador <otavio@...ystems.com.br>,
	Javier Martinez Canillas <javier@...hile0.org>,
	Christian Hohnstaedt <chohnstaedt@...ominate.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] smsc: RFC: Workaround for problems with lan8710 phy auto
 MDI-X

On Fri, 30 Nov 2012, Peter Turczak wrote:

> while debugging network outages on a customers hardware I found, that 
> the MDI-X function of the lan8710 phy seemed to cause trouble. When 
> connecting to almost any kind of 100/1000MBit switch, the link would 
> seem to come up and data where sent out to the network. But all incoming 
> packets got lost somehow. This is quite bad, as the system runs from 
> nfsroot while booting up during development.
> 
> When I disabled the auto MDI-X function of the phy the problem went away.
> 
> Signed-off-by: Peter Turczak <pt@...consequence.de>
> ---
>  drivers/net/phy/Kconfig |   10 ++++++++++
>  drivers/net/phy/smsc.c  |   15 +++++++++++++++
>  include/linux/smscphy.h |    5 +++++
>  3 files changed, 30 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
> index 961f0b2..341f5aa 100644
> --- a/drivers/net/phy/Kconfig
> +++ b/drivers/net/phy/Kconfig
> @@ -60,6 +60,16 @@ config SMSC_PHY
>  	---help---
>  	  Currently supports the LAN83C185, LAN8187 and LAN8700 PHYs
>  
> +config SMSC_PHY_DISABLE_AUTOX
> +	bool "Disable MDI-X upon start"
> +	depends on SMSC_PHY
> +	---help---
> +	  When you experience problems estabishing a stable connection
> +	  to a network and you have e.g. a LAN8710 ethernet phy
> +	  this option might help you out.
> +
> +	  In doubt, say N
> +

I am not sure whether compile-time option for something like this is 
appropriate. Kernel module parameter, perhaps?

Of course it'd be far better if faulty hardware can be autodetected in 
runtime.

-- 
Jiri Kosina
SUSE Labs
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