Imx6 SabreLite board ethernet troubles

[leonidandronov2]

Hello,

We have bought several imx6 sabrelite rev-2 boards (6-20-13) which we planned to use in our project replacing imx53 boards. But we have troubles to connect this boards to our ethernet devices (no link or unstable link) . There are also troubles to connect board to commonly used equipment . Some ethernet switches can be connected to sabrelite  boards fine in almost any cases with any cable, some switches work only with certain cables, some devices do not bring link up with any cable. Some gigabit switches can be connected succesfully to sabrelite only with disabled gigabit feature or autonegotiation on imx board but this configuration does not help to connect to other devices. And so on – no system was found yet. It is unpredictable. There was no troubles with ethernet connections on imx53 board…

Has anyone else seen such behavior? Is it a known issue?

[leonidandronov2]

Hi Gary,

There is no system yet in length, category, crossover or not, count of pairs of cable that reproduces issue... :smileysad: I have "good" cables and "bad" cables and they can work in one case and not in other. But it is so only in experiments with SabreLite. With other devices those all cables are "good". :smileysad: There are some cables that work fine in almost every case. May be you should  try several different cables to try to reproduce issue.. I dont know.

Regards, Leonid

[gary_bisson]

Hi Leonid,

Can you try one experiment, disabling the Gigabit feature. I know it might not what you want but it might help us understand the issue.

In U-Boot, issue the following commands:

=> setenv disable_giga 1

=> saveenv

=> reset

Let me know if this helps.

Regards,

Gary

[leonidandronov2]

Hi Gary,

I have tried to disable Gigabit feature in uboot. There are no notable changes with 100Mbit devices. Two sabrelite boards cannot be connected with this configuration applied to one of them or to both. (I had to delete disable_giga variable to return functionality back, "env default -f disable_giga")

Regards, Leonid

[gary_bisson]

Hi Leonid,

Ok, thanks for testing this out. One other test would be to discard the green feature of the Micrel PHY (see datasheet). This feature is enabled along with autonegotiation, so could you try disabling autoneg using ethtool for instance?

Let me know if this helps.

Regards,

Gary

[leonidandronov2]

Hi Gary,

Unfortunately I have no built ethtool for latest yocto jethro release. And I have some troubles to build all yocto jethro release from scratch because some repos do not fetch... If you have a working ethtool please send me it if you can.

Earlier I tried to use a working ethtool with older linux release 3.10.x and it was helpful in some cases. I have found that good scenario is to reset PHY with

"ethtool -r eth0"

and then after 3-4 seconds sleeping do

"ethtool -s eth0 autoneg off" .

But it did not resolve issue entirely. There are still device/cable combinations with no link.

Regards Leonid

[leonidandronov2]

Hi Gary,

Thank you for working ethtool utility. I have done some experiments with it on jethro release.

Configuring PHY with 10Mbit/HalfDuplex/AutonegotiationOff helped to resolve issue in all problem cases that I currently tried. I will continue experiments. (ethtool -s eth0 speed 10 duplex half autoneg off)

100Mbit/FullDuplex/AutonegotiationOff configuration is good in majority of cases but for some cable/device combinations

ethernet hangs totally (led lights regardless cable connected or not). I need to reset board, ethtool manipulations donot help.

Linux console output in this case (pretty much same messages):

libphy: 2188000.ethernet:06 - Link is Up - 100/Full

libphy: 2188000.ethernet:06 - Link is Down

libphy: 2188000.ethernet:06 - Link is Up - 100/Full

libphy: 2188000.ethernet:06 - Link is Down

<.....same lines.......>

libphy: 2188000.ethernet:06 - Link is Down

libphy: 2188000.ethernet:06 - Link is Up - 100/Full

(NULL net_device): MDIO read timeout

Regards, Leonid

[ronbolts]

Hello All:

I am experiencing the same exact issue.  Phy is UP and then Phy is DN.  It rarely happens.  Only on specific devices that I connect to.  Never have seen the problem when connected to a swtich.  We have a i.MX53 with a PHY LAN8720 running Freescale Kernel 2.6.35.  We have tried disabling auto negotian along with energy detect on our board.  Also used both the generic PHY Driver and the speficic SMSC Driver.  All to on avail.  Trying now to figure out the PHY of the devices that are failing.  I believe the problem is in the hardware layer of the PHYs. Did try disabling auto negotiation on both devices once the link is up and the link will stay up.  However, this is not a viable solution since we will not be able to modify the code on every device with the problem.

My test system is connecting to a Nitrogen6x board running Android.  When the Nitrogen6x is connected to my device the problem is occurs.

Regards,

Ron