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Tobias WaldekranzandJoachim Wiberg
d36899b49e
Even when `managed = "in-band-status";` was specified on a port, mv88e6xxx would insist on forcing the values that were supposed to be automatically picked up by the MAC via in-band signaling. In the case of USXGMII links on 6393X, forcing the link bit would sometimes, for reasons that are not understood, cause the SERDES to reset its USXGMII link partner base page (register 4.0xf0a2) to 0, which it would then interpret as 10M/half-duplex. As a result, the SERDES would erroneously perform rate-matching to 10M on egress towards the PHY (which is configured for 10G/full-duplex), leading to nothing but dropped packets and much sadness. This can most easily be reproduced by the following setup: .------------. | .-----. .-------. | | p9 +---+ 3310P +--. | 6393X :-----: :-------: | T- or X-Units looped via external cable | | p10 +---+ 3310P +--' | '-----' '-------' '------------' Make sure that neither p9 nor p10 are managed using in-band-status. 1. ip link set dev p9 up; ip link set dev p10 up 2. ip link set dev p9 down 3. ip link set dev p9 up After step (3), p10 will experience the failure described above in about 3/4 of the cases. In the cases where the issue does not arise, simply repeat steps (2) and (3).