Hi Nicolas We are currently debugging an issue with the KSZ8873 with the LinkMD Feature to measure Cable-Failures. We implemented all steps described in corresponding section of the Datasheet:
3.1.12 LINKMD ® CABLE DIAGNOSTICS It is also already clear that this feature is only available to the second of the ports due to an errata on the status register of the first port. What we see is, that in some of the measurements the detection returns "11 = cable diagnostic test failed (invalid test)". In the Datasheet of the KSZ8001 this failure is a little bit more detailed desribed: <quote> The ‘11’ case, Invalid test, occurs when it is not possible for the KSZ8001 to shut down the link partner. In this case, the test is not run, since it would not be possible for the KSZ8001 to determine if the detected signal is a reflection of the signal generated or a signal from another source. </quote> The datasheet also mentions that it needs to disable HP Auto MDIX (switch to Micrel MDIX) which was left out in the KSZ8873 Datasheet. We fiddled with all mentioned bits but did not get any stable measurement with the KSZ8873. The odd thing about it, is the fact that it works for some repeatable times without changing anything in the whole system and from now to then it returns the invalid test failure. We also connected two KSZ8873 switches to disable MDIX on both sides before the test. Could you help us or poke somebody who could describe the issue we see? Thanks, Michael -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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