BCM module diagnostics replace timestamp probes: bringup forces EEE off and runs ECD (re-run on every reset, re-baselining past its blip), 1 Hz SNR margin + corrected counters on panel and console; X520 bench divergences bypassed and tracked in open-questions

system.go

@@ -567,18 +567,40 @@ func checkCoalesce(fd int, ifname string, rxUsecs, txUsecs uint32) checkResult {
 		return fmt.Sprintf("adaptive rx=%d tx=%d rx-usecs=%d tx-usecs=%d",
 			e.useAdaptiveRxCoalesce, e.useAdaptiveTxCoalesce, e.rxCoalesceUsecs, e.txCoalesceUsecs)
 	}
-	if ec.useAdaptiveRxCoalesce == 0 && ec.useAdaptiveTxCoalesce == 0 &&
-		ec.rxCoalesceUsecs == rxUsecs && ec.txCoalesceUsecs == txUsecs {
+	settled := func(e ethtoolCoalesce, tx uint32) bool {
+		return e.useAdaptiveRxCoalesce == 0 && e.useAdaptiveTxCoalesce == 0 &&
+			e.rxCoalesceUsecs == rxUsecs && e.txCoalesceUsecs == tx
+	}
+	if settled(ec, txUsecs) {
 		res.state = desc(ec)
 		return res
 	}
 	was := desc(ec)
-	ec.cmd = unix.ETHTOOL_SCOALESCE
-	ec.useAdaptiveRxCoalesce = 0
-	ec.useAdaptiveTxCoalesce = 0
-	ec.rxCoalesceUsecs = rxUsecs
-	ec.txCoalesceUsecs = txUsecs
-	if err := ethtoolCall(fd, ifname, unsafe.Pointer(&ec)); err != nil {
+	set := func(tx uint32) error {
+		s := ec
+		s.cmd = unix.ETHTOOL_SCOALESCE
+		s.useAdaptiveRxCoalesce = 0
+		s.useAdaptiveTxCoalesce = 0
+		s.rxCoalesceUsecs = rxUsecs
+		s.txCoalesceUsecs = tx
+		return ethtoolCall(fd, ifname, unsafe.Pointer(&s))
+	}
+	err = set(txUsecs)
+	// A driver running mixed rx/tx vectors has one moderation value per
+	// vector and rejects a tx-specific one: rx-usecs covers both, and get
+	// reports the tx side as zero.
+	if err == unix.EINVAL {
+		if settled(ec, 0) {
+			res.state = desc(ec) + " (tx shares rx)"
+			return res
+		}
+		if err = set(0); err == nil {
+			res.fixed = true
+			res.state = fmt.Sprintf("was %s, now adaptive off rx-usecs=%d shared with tx", was, rxUsecs)
+			return res
+		}
+	}
+	if err != nil {
 		res.err = err
 		res.state = "could not set"
 		return res