From: Lothar Waßmann <l...@karo-electronics.de> Sent: Monday, November 30, 2015 2:56 PM > To: Duan Fugang-B38611 > Cc: Andrew Lunn; David S. Miller; Estevam Fabio-R49496; Kevin Hao; Lucas > Stach; Philippe Reynes; Russell King; Uwe Kleine-K?nig; linux- > ker...@vger.kernel.org; netdev@vger.kernel.org; Stefan Agner > Subject: Re: [PATCH] net: fec: fix enet_out clock handling > > Hi, > > > From: Lothar Waßmann <l...@karo-electronics.de> Sent: Friday, November > > 27, 2015 9:39 PM > > > To: Andrew Lunn; David S. Miller; Estevam Fabio-R49496; Kevin Hao; > > > Lothar Waßmann; Lucas Stach; Duan Fugang-B38611; Philippe Reynes; > > > Russell King; Uwe Kleine-König; linux-ker...@vger.kernel.org; > > > netdev@vger.kernel.org; Stefan Agner > > > Subject: [PATCH] net: fec: fix enet_out clock handling > > > > > > When ENET_OUT is being used as reference clock for an external PHY, > > > the clock must not be disabled while the PHY is active. Otherwise > > > the PHY may lose its internal state and require a reset to become > functional again. > > > > > > A symptom for this bug is a network interface that constantly > > > toggles between UP and DOWN state: > > > fec 800f0000.ethernet eth0: Link is Up - 100Mbps/Full - flow control > > > rx/tx fec 800f0000.ethernet eth0: Link is Down fec 800f0000.ethernet > eth0: > > > Link is Up - 100Mbps/Full - flow control rx/tx fec 800f0000.ethernet > eth0: > > > Link is Down [...] > > > > > > Signed-off-by: Lothar Waßmann <l...@karo-electronics.de> > > > --- > > > drivers/net/ethernet/freescale/fec_main.c | 34 > > > +++++++++++++------------ > > > ------ > > > 1 file changed, 14 insertions(+), 20 deletions(-) > > > > > > > When MAC is not ready with clocks disabled, it is not necessary to > supply clock for PHY. In fact, PHY also is not ready, why does it need > clock ? > > For your problem, you must add PHY reset in your dts file to resolve > your problem. > > > The phy-reset-gpio property is set in the DTB. But fec_reset_phy() which > asserts the RESET is only called from within the probe() function. > It should probably be called from fec_restart() instead? > After enet_out clock enable, you can call fec_reset_phy() do phy reset. Don't put it in .fec_restart() function because Cable hotplug test cause phy registers reset to HW default status.
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