On Sun, 2008-12-14 at 12:38 +0000, Steve Glendinning wrote:
[...]

+/**
+ * mii_resolve_flowctrl_fdx
+ * @lcladv: value of MII ADVERTISE register
+ * @rmtadv: value of MII LPA register
+ *
+ * Resolve full duplex flow control as per IEEE 802.3-2005 table 28B-3
+ */
+static inline u8 mii_resolve_flowctrl_fdx(u16 lcladv, u16 rmtadv)
+{
+	u8 cap = 0;
+
+	if (lcladv & ADVERTISE_PAUSE_CAP) {
+		if (lcladv & ADVERTISE_PAUSE_ASYM) {
+			if (rmtadv & LPA_PAUSE_CAP)
+				cap = FLOW_CTRL_TX | FLOW_CTRL_RX;
+			else if (rmtadv & LPA_PAUSE_ASYM)
+				cap = FLOW_CTRL_RX;
+		} else {
+			if (rmtadv & LPA_PAUSE_CAP)
+				cap = FLOW_CTRL_TX | FLOW_CTRL_RX;
+		}
+	} else if (lcladv & ADVERTISE_PAUSE_ASYM) {
+		if ((rmtadv & LPA_PAUSE_CAP) && (rmtadv & LPA_PAUSE_ASYM))
+			cap = FLOW_CTRL_TX;
+	}
+
+	return cap;
+}

There's a rather more elegant way to write this, which is:

	if (lcladv & rmtadv & ADVERTISE_PAUSE_CAP) {
		cap = FLOW_CTRL_TX | FLOW_CTRL_RX;
	} else if (lcladv & rmtadv & ADVERTISE_PAUSE_ASYM) {
		if (lcladv & ADVERTISE_PAUSE_CAP)
			cap = FLOW_CTRL_RX;
		else if (rmtadv & ADVERTISE_PAUSE_CAP)
			cap = FLOW_CTRL_TX;
	}

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
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