mvneta: Fix 64-bit MIB reads

[markj]

Summary

It appears we must read them as 2 4-byte words, lower address first.
Otherwise both reads return the same value, resulting in bogus byte
counter values.

[mw]

sys/dev/neta/if_mvneta.c

1193

Please replace the for loop with mvneta_clear_mib()

[markj]

Use mvneta_clear_mib().

[mw]

sys/dev/neta/if_mvneta.c

3540

Sorry for not spotting this before - val is unitialized, so we need to make sure, the upper half of it is not a random data. Please add:

val = 0;

Otherwise LGTM.

[markj]

sys/dev/neta/if_mvneta.c

3540

I don't follow. We assign val = MVNETA_READ_MIB(sc, mib->regnum) a couple of lines below. The right-hand side of that statement will be promoted to a 64-bit value before the assignment.

[mw]

sys/dev/neta/if_mvneta.c

3540

You are right.