tg3: Fix 5719 internal FIFO overflow problem

Under load, there an internal FIFO can overflow on the 5719.  The fix is
to scale back the PCIe maximum read request size based on the current
link speed and width.

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Reviewed-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tg3.c

@@ -6985,7 +6985,7 @@ static void tg3_restore_pci_state(struct tg3 *tp)
 
 	if (GET_ASIC_REV(tp->pci_chip_rev_id) != ASIC_REV_5785) {
 		if (tp->tg3_flags2 & TG3_FLG2_PCI_EXPRESS)
-			pcie_set_readrq(tp->pdev, 4096);
+			pcie_set_readrq(tp->pdev, tp->pcie_readrq);
 		else {
 			pci_write_config_byte(tp->pdev, PCI_CACHE_LINE_SIZE,
 					      tp->pci_cacheline_sz);
@@ -7179,7 +7179,7 @@ static int tg3_chip_reset(struct tg3 *tp)
 				      tp->pcie_cap + PCI_EXP_DEVCTL,
 				      val16);
 
-		pcie_set_readrq(tp->pdev, 4096);
+		pcie_set_readrq(tp->pdev, tp->pcie_readrq);
 
 		/* Clear error status */
 		pci_write_config_word(tp->pdev,
@@ -13366,7 +13366,45 @@ static int __devinit tg3_get_invariants(struct tg3 *tp)
 
 		tp->tg3_flags2 |= TG3_FLG2_PCI_EXPRESS;
 
-		pcie_set_readrq(tp->pdev, 4096);
+		tp->pcie_readrq = 4096;
+		if (GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5719) {
+			u16 word;
+
+			pci_read_config_word(tp->pdev,
+					     tp->pcie_cap + PCI_EXP_LNKSTA,
+					     &word);
+			switch (word & PCI_EXP_LNKSTA_CLS) {
+			case PCI_EXP_LNKSTA_CLS_2_5GB:
+				word &= PCI_EXP_LNKSTA_NLW;
+				word >>= PCI_EXP_LNKSTA_NLW_SHIFT;
+				switch (word) {
+				case 2:
+					tp->pcie_readrq = 2048;
+					break;
+				case 4:
+					tp->pcie_readrq = 1024;
+					break;
+				}
+				break;
+
+			case PCI_EXP_LNKSTA_CLS_5_0GB:
+				word &= PCI_EXP_LNKSTA_NLW;
+				word >>= PCI_EXP_LNKSTA_NLW_SHIFT;
+				switch (word) {
+				case 1:
+					tp->pcie_readrq = 2048;
+					break;
+				case 2:
+					tp->pcie_readrq = 1024;
+					break;
+				case 4:
+					tp->pcie_readrq = 512;
+					break;
+				}
+			}
+		}
+
+		pcie_set_readrq(tp->pdev, tp->pcie_readrq);
 
 		pci_read_config_word(tp->pdev,
 				     tp->pcie_cap + PCI_EXP_LNKCTL,

drivers/net/tg3.h

@@ -2948,6 +2948,7 @@ struct tg3 {
 	int				pcix_cap;
 	int				pcie_cap;
 	};
+	int				pcie_readrq;
 
 	struct mii_bus			*mdio_bus;
 	int				mdio_irq[PHY_MAX_ADDR];