* net/fec: Unable to get a permanent link when connecting to a PC
@ 2014-09-19 9:33 to-fleischer at t-online.de
2014-09-22 8:06 ` Stefan Wahren
0 siblings, 1 reply; 2+ messages in thread
From: to-fleischer at t-online.de @ 2014-09-19 9:33 UTC (permalink / raw)
To: linux-arm-kernel
I have an i.MX283 board with a KSZ8081 PHY that is connected to the controller
via RMII. The PHY's interrupt line is currently unused, but connected to the
controller. The board runs the linux version 3.17-rc5.
When I connect the board directly to a PC the ethernet link goes up and a second
later down. This is repeated again and again.
After some investigation I found that this is caused by the reset of the FEC at
the begin of fec_restart() that is called by fec_enet_adjust_link() if the link
is up.
Due to the reset the mode is set to MII. After switching back to RMII the PHY
seems to restart the autonegotiation. Since this takes a while the next call of
phy_state_machine() detects that the link is down.
It would work, if the reset in fec_restart is avoided for the case that the link
goes up and the fec is still stopped.
Its quite remarkable that this issue does not occur if I connect the board to a
switch or if I use the PHY's interrupt line.
What do you think?
Best Regards,
Torsten Fleischer
^ permalink raw reply [flat|nested] 2+ messages in thread
* net/fec: Unable to get a permanent link when connecting to a PC
2014-09-19 9:33 net/fec: Unable to get a permanent link when connecting to a PC to-fleischer at t-online.de
@ 2014-09-22 8:06 ` Stefan Wahren
0 siblings, 0 replies; 2+ messages in thread
From: Stefan Wahren @ 2014-09-22 8:06 UTC (permalink / raw)
To: linux-arm-kernel
Am 19.09.2014 um 11:33 schrieb to-fleischer at t-online.de:
> I have an i.MX283 board with a KSZ8081 PHY that is connected to the controller
> via RMII. The PHY's interrupt line is currently unused, but connected to the
> controller. The board runs the linux version 3.17-rc5.
> When I connect the board directly to a PC the ethernet link goes up and a second
> later down. This is repeated again and again.
> After some investigation I found that this is caused by the reset of the FEC at
> the begin of fec_restart() that is called by fec_enet_adjust_link() if the link
> is up.
> Due to the reset the mode is set to MII. After switching back to RMII the PHY
> seems to restart the autonegotiation. Since this takes a while the next call of
> phy_state_machine() detects that the link is down.
> It would work, if the reset in fec_restart is avoided for the case that the link
> goes up and the fec is still stopped.
>
> Its quite remarkable that this issue does not occur if I connect the board to a
> switch or if I use the PHY's interrupt line.
>
> What do you think?
>
> Best Regards,
> Torsten Fleischer
>
Add netdev list
Best regards
Stefan Wahren
^ permalink raw reply [flat|nested] 2+ messages in thread
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2014-09-22 8:06 ` Stefan Wahren
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