e1000e: fix buffer overrun while the I219 is processing DMA transactions

Intel® 100/200 Series Chipset platforms reduced the round-trip
latency for the LAN Controller DMA accesses, causing in some high
performance cases a buffer overrun while the I219 LAN Connected
Device is processing the DMA transactions. I219LM and I219V devices
can fall into unrecovered Tx hang under very stressfully UDP traffic
and multiple reconnection of Ethernet cable. This Tx hang of the LAN
Controller is only recovered if the system is rebooted. Slightly slow
down DMA access by reducing the number of outstanding requests.
This workaround could have an impact on TCP traffic performance
on the platform. Disabling TSO eliminates performance loss for TCP
traffic without a noticeable impact on CPU performance.

Please, refer to I218/I219 specification update:
https://www.intel.com/content/www/us/en/embedded/products/networking/
ethernet-connection-i218-family-documentation.html

Signed-off-by: Sasha Neftin <[email protected]>
Reviewed-by: Dima Ruinskiy <[email protected]>
Reviewed-by: Raanan Avargil <[email protected]>
Tested-by: Aaron Brown <[email protected]>
Signed-off-by: Jeff Kirsher <[email protected]>

Author: aneftin

drivers/net/ethernet/intel/e1000e/netdev.c

@@ -3021,16 +3021,18 @@ static void e1000_configure_tx(struct e1000_adapter *adapter)
 
 	hw->mac.ops.config_collision_dist(hw);
 
-	/* SPT and CNP Si errata workaround to avoid data corruption */
-	if (hw->mac.type >= e1000_pch_spt) {
+	/* SPT and KBL Si errata workaround to avoid data corruption */
+	if (hw->mac.type == e1000_pch_spt) {
 		u32 reg_val;
 
 		reg_val = er32(IOSFPC);
 		reg_val |= E1000_RCTL_RDMTS_HEX;
 		ew32(IOSFPC, reg_val);
 
 		reg_val = er32(TARC(0));
-		reg_val |= E1000_TARC0_CB_MULTIQ_3_REQ;
+		/* SPT and KBL Si errata workaround to avoid Tx hang */
+		reg_val &= ~BIT(28);
+		reg_val |= BIT(29);
 		ew32(TARC(0), reg_val);
 	}
 }