Messages in this thread | | | Date | Fri, 18 Oct 2019 18:01:16 +0200 | From | Andrew Lunn <> | Subject | Re: [PATCH net-next 2/2] net: phy: Add ability to debug RGMII connections |
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> I don't think you are following the big picture of what I am saying. I > was trying to follow Florian's intention (first make sure I understand > it) and suggest that the FCS checking code in the patch he submitted > is not doing what it was intended to. I am getting apparent FCS > mismatches reported by the program, when I know full well that the MAC > I am testing on would have dropped those frames were they really > invalid.
I think this FCS check is not needed. If we feed the MAC random data, something like 1 in 65535 will have a valid FCS and get passed up. I've not seen this happen with Ethernet, but i have seen other network technologies wrong decoding noise on the line and passing up frames with around 1 in 65536 probability.
But then having the correct Ethertype is another 1 in 65536. So it seem pretty improbably we do receiver a packet in this method which is bad. So i would say, any packet received here is a good packet, and indicate the RGMII mode works. If we don't receive a packet, the mode is very probably bad.
Andrew
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