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Date: Thu, 10 Sep 2009 13:04:32 -0500
From: Scott Wood <scottwood@freescale.com>
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To: avorontsov@ru.mvista.com
Subject: Re: [PATCH v2 3/3] ucc_geth: Fix hangs after switching from full
	to	half duplex
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Cc: linuxppc-dev@ozlabs.org, netdev@vger.kernel.org,
	Andy Fleming <afleming@freescale.com>, David Miller <davem@davemloft.net>,
	Timur Tabi <timur@freescale.com>
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Anton Vorontsov wrote:
> MPC8360 QE UCC ethernet controllers hang when changing link duplex
> under a load (a bit of NFS activity is enough).
> 
>   PHY: mdio@e0102120:00 - Link is Up - 1000/Full
>   sh-3.00# ethtool -s eth0 speed 100 duplex half autoneg off
>   PHY: mdio@e0102120:00 - Link is Down
>   PHY: mdio@e0102120:00 - Link is Up - 100/Half
>   NETDEV WATCHDOG: eth0 (ucc_geth): transmit queue 0 timed out
>   ------------[ cut here ]------------
>   Badness at c01fcbd0 [verbose debug info unavailable]
>   NIP: c01fcbd0 LR: c01fcbd0 CTR: c0194e44
>   ...
> 
> The cure is to disable the controller before changing speed/duplex
> and enable it afterwards.
> 
> Since ugeth_graceful_stop_{tx,rx} now may be called from an atomic
> context, switch the two functions from msleep() to mdelay().

Ouch.  Can we put this in a workqueue or something?

-Scott