skge: fix ram buffer size calculation

This fixes problems with transmit hangs on older fiber based SysKonnect boards.

Adjust ram buffer sizing calculation to make it correct on all boards
and make it like the code in sky2 driver.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/skge.c b/drivers/net/skge.c
index 2aae9fe..e593585 100644
--- a/drivers/net/skge.c
+++ b/drivers/net/skge.c
@@ -2403,32 +2403,31 @@
 	return err;
 }
 
-static void skge_ramset(struct skge_hw *hw, u16 q, u32 start, size_t len)
+/* Assign Ram Buffer allocation to queue */
+static void skge_ramset(struct skge_hw *hw, u16 q, u32 start, u32 space)
 {
 	u32 end;
 
-	start /= 8;
-	len /= 8;
-	end = start + len - 1;
+	/* convert from K bytes to qwords used for hw register */
+	start *= 1024/8;
+	space *= 1024/8;
+	end = start + space - 1;
 
 	skge_write8(hw, RB_ADDR(q, RB_CTRL), RB_RST_CLR);
 	skge_write32(hw, RB_ADDR(q, RB_START), start);
+	skge_write32(hw, RB_ADDR(q, RB_END), end);
 	skge_write32(hw, RB_ADDR(q, RB_WP), start);
 	skge_write32(hw, RB_ADDR(q, RB_RP), start);
-	skge_write32(hw, RB_ADDR(q, RB_END), end);
 
 	if (q == Q_R1 || q == Q_R2) {
+		u32 tp = space - space/4;
+
 		/* Set thresholds on receive queue's */
-		skge_write32(hw, RB_ADDR(q, RB_RX_UTPP),
-			     start + (2*len)/3);
-		skge_write32(hw, RB_ADDR(q, RB_RX_LTPP),
-			     start + (len/3));
-	} else {
-		/* Enable store & forward on Tx queue's because
-		 * Tx FIFO is only 4K on Genesis and 1K on Yukon
-		 */
+		skge_write32(hw, RB_ADDR(q, RB_RX_UTPP), tp);
+		skge_write32(hw, RB_ADDR(q, RB_RX_LTPP), space/4);
+	} else if (hw->chip_id != CHIP_ID_GENESIS)
+		/* Genesis Tx Fifo is too small for normal store/forward */
 		skge_write8(hw, RB_ADDR(q, RB_CTRL), RB_ENA_STFWD);
-	}
 
 	skge_write8(hw, RB_ADDR(q, RB_CTRL), RB_ENA_OP_MD);
 }
@@ -2456,7 +2455,7 @@
 	struct skge_port *skge = netdev_priv(dev);
 	struct skge_hw *hw = skge->hw;
 	int port = skge->port;
-	u32 chunk, ram_addr;
+	u32 ramaddr, ramsize, rxspace;
 	size_t rx_size, tx_size;
 	int err;
 
@@ -2511,14 +2510,15 @@
 	spin_unlock_bh(&hw->phy_lock);
 
 	/* Configure RAMbuffers */
-	chunk = hw->ram_size / ((hw->ports + 1)*2);
-	ram_addr = hw->ram_offset + 2 * chunk * port;
+	ramsize = (hw->ram_size - hw->ram_offset) / hw->ports;
+	ramaddr = hw->ram_offset + port * ramsize;
+	rxspace = 8 + (2*(ramsize - 16))/3;
 
-	skge_ramset(hw, rxqaddr[port], ram_addr, chunk);
+	skge_ramset(hw, rxqaddr[port], ramaddr, rxspace);
+	skge_ramset(hw, txqaddr[port], ramaddr + rxspace, ramsize - rxspace);
+
 	skge_qset(skge, rxqaddr[port], skge->rx_ring.to_clean);
-
 	BUG_ON(skge->tx_ring.to_use != skge->tx_ring.to_clean);
-	skge_ramset(hw, txqaddr[port], ram_addr+chunk, chunk);
 	skge_qset(skge, txqaddr[port], skge->tx_ring.to_use);
 
 	/* Start receiver BMU */
@@ -3450,15 +3450,12 @@
 	if (hw->chip_id == CHIP_ID_GENESIS) {
 		if (t8 == 3) {
 			/* special case: 4 x 64k x 36, offset = 0x80000 */
-			hw->ram_size = 0x100000;
-			hw->ram_offset = 0x80000;
+			hw->ram_size = 1024;
+			hw->ram_offset = 512;
 		} else
 			hw->ram_size = t8 * 512;
-	}
-	else if (t8 == 0)
-		hw->ram_size = 0x20000;
-	else
-		hw->ram_size = t8 * 4096;
+	} else /* Yukon */
+		hw->ram_size = t8 ? t8 * 4 : 128;
 
 	hw->intr_mask = IS_HW_ERR;