netdev - Re: net/fec on i.MX28: failure after network cable unplug or device down

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Date:	Mon, 10 Oct 2011 15:52:30 +0200
From:	Lothar Waßmann <LW@...O-electronics.de>
To:	Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Cc:	netdev@...r.kernel.org, Shawn Guo <shawn.guo@...escale.com>,
	Wolfram Sang <w.sang@...gutronix.de>
Subject: Re: net/fec on i.MX28: failure after network cable unplug or device down

Hi,

Uwe Kleine-König writes:
> Hello,
> 
> I currently see the problem on two different i.MX28 based system
> (Freescale's mx28evk and a Karo TX28) that after unplugging and
> reconnection of the network cable or ifconfig down; ifconfig up; the
> network is dead. That means nothing is sent or received anymore.
> 
I already solved this problem (and some others too), but wasn't able
to send any patch yet.

The FEC of the i.MX28 requires the ETHER_EN bit in the ECR to be set
for the MII interface to work. Resetting the interface upon shutdown
is required though, because otherwise the receiver will remain active
and use the stale DMA descriptors in memory to store received packets!

Furthermore the (R)MII mode must be configured correctly in the RCR
register.

The current state of my patch is appended for reference.


Lothar Waßmann
-- 

Download attachment "fec-cleanup" of type "application/octet-stream" (3610 bytes)

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