[PATCH] sky2: beter ram buffer partitioning

Different chips have different sizes of ram buffers, and some versions have
no ram buffer at all!.  Be more careful about sizing the ram usage because
it maybe a problem if vendor keeps changing sizes.

There is the (unlikely) possibility that some of the errors on some of the
chips have been caused by partitioning not on a 1K boundary.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/sky2.c

@@ -696,10 +696,15 @@ static void sky2_mac_init(struct sky2_hw *hw, unsigned port)
 
 }
 
-/* Assign Ram Buffer allocation in units of 64bit (8 bytes) */
-static void sky2_ramset(struct sky2_hw *hw, u16 q, u32 start, u32 end)
+/* Assign Ram Buffer allocation to queue */
+static void sky2_ramset(struct sky2_hw *hw, u16 q, u32 start, u32 space)
 {
-	pr_debug(PFX "q %d %#x %#x\n", q, start, end);
+	u32 end;
+
+	/* convert from K bytes to qwords used for hw register */
+	start *= 1024/8;
+	space *= 1024/8;
+	end = start + space - 1;
 
 	sky2_write8(hw, RB_ADDR(q, RB_CTRL), RB_RST_CLR);
 	sky2_write32(hw, RB_ADDR(q, RB_START), start);
@@ -708,7 +713,6 @@ static void sky2_ramset(struct sky2_hw *hw, u16 q, u32 start, u32 end)
 	sky2_write32(hw, RB_ADDR(q, RB_RP), start);
 
 	if (q == Q_R1 || q == Q_R2) {
-		u32 space = end - start + 1;
 		u32 tp = space - space/4;
 
 		/* On receive queue's set the thresholds
@@ -1138,7 +1142,7 @@ static int sky2_up(struct net_device *dev)
 	struct sky2_port *sky2 = netdev_priv(dev);
 	struct sky2_hw *hw = sky2->hw;
 	unsigned port = sky2->port;
-	u32 ramsize, rxspace, imask;
+	u32 ramsize, imask;
 	int cap, err = -ENOMEM;
 	struct net_device *otherdev = hw->dev[sky2->port^1];
 
@@ -1191,20 +1195,25 @@ static int sky2_up(struct net_device *dev)
 
 	sky2_mac_init(hw, port);
 
-	/* Determine available ram buffer space in qwords.  */
-	ramsize = sky2_read8(hw, B2_E_0) * 4096/8;
+	/* Register is number of 4K blocks on internal RAM buffer. */
+	ramsize = sky2_read8(hw, B2_E_0) * 4;
+	printk(KERN_INFO PFX "%s: ram buffer %dK\n", dev->name, ramsize);
 
-	if (ramsize > 6*1024/8)
-		rxspace = ramsize - (ramsize + 2) / 3;
-	else
-		rxspace = ramsize / 2;
+	if (ramsize > 0) {
+		u32 rxspace;
 
-	sky2_ramset(hw, rxqaddr[port], 0, rxspace-1);
-	sky2_ramset(hw, txqaddr[port], rxspace, ramsize-1);
+		if (ramsize < 16)
+			rxspace = ramsize / 2;
+		else
+			rxspace = 8 + (2*(ramsize - 16))/3;
 
-	/* Make sure SyncQ is disabled */
-	sky2_write8(hw, RB_ADDR(port == 0 ? Q_XS1 : Q_XS2, RB_CTRL),
-		    RB_RST_SET);
+		sky2_ramset(hw, rxqaddr[port], 0, rxspace);
+		sky2_ramset(hw, txqaddr[port], rxspace, ramsize - rxspace);
+
+		/* Make sure SyncQ is disabled */
+		sky2_write8(hw, RB_ADDR(port == 0 ? Q_XS1 : Q_XS2, RB_CTRL),
+			    RB_RST_SET);
+	}
 
 	sky2_qset(hw, txqaddr[port]);