e1000: Jumbo frames fixes for 82573

Disable jumbo frames for 82573L alltogether and when ASPM is enabled
since the hardware has problems with it. For the NICs that do support
this in the 82573 series we set ERT_2048 to attempt to receive as much
traffic as early as we can.
Signed-off-by: NBruce Allan <bruce.w.allan@intel.com>
Signed-off-by: NAuke Kok <auke-jan.h.kok@intel.com>

drivers/net/e1000/e1000_main.c

@@ -3138,11 +3138,13 @@ e1000_change_mtu(struct net_device *netdev, int new_mtu)
 		}
 		break;
 	case e1000_82573:
-		/* only enable jumbo frames if ASPM is disabled completely
-		 * this means both bits must be zero in 0x1A bits 3:2 */
+		/* Jumbo Frames not supported if:
+		 * - this is not an 82573L device
+		 * - ASPM is enabled in any way (0x1A bits 3:2) */
 		e1000_read_eeprom(&adapter->hw, EEPROM_INIT_3GIO_3, 1,
 		                  &eeprom_data);
-		if (eeprom_data & EEPROM_WORD1A_ASPM_MASK) {
+		if ((adapter->hw.device_id != E1000_DEV_ID_82573L) ||
+		    (eeprom_data & EEPROM_WORD1A_ASPM_MASK)) {
 			if (max_frame > MAXIMUM_ETHERNET_FRAME_SIZE) {
 				DPRINTK(PROBE, ERR,
 			            	"Jumbo Frames not supported.\n");
@@ -3150,6 +3152,8 @@ e1000_change_mtu(struct net_device *netdev, int new_mtu)
 			}
 			break;
 		}
+		/* ERT will be enabled later to enable wire speed receives */
+
 		/* fall through to get support */
 	case e1000_82571:
 	case e1000_82572: