e1000e: slow performance between two 82579 connected via 10Mbit hub
Two 82579 LOMs connected via a 10Mb hub experience extraordinarily low
performance. This is because 82579 is excessively aggressive on transmit
at 10Mb half-duplex and will not provide sufficient time for the link
partner to transmit. When the link partner is also 82579, the result is a
lot of collisions (and corresponding re-transmits) that cause the poor
performance. To work-around this issue, significantly increase the IPG in
the MAC to allow enough gap for the link partner to transmit and reduce the
Rx latency in the analog PHY to 0 to reduce the number of collisions.
Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/e1000e/ich8lan.h b/drivers/net/ethernet/intel/e1000e/ich8lan.h
index 8bf4655..00ba6c9 100644
--- a/drivers/net/ethernet/intel/e1000e/ich8lan.h
+++ b/drivers/net/ethernet/intel/e1000e/ich8lan.h
@@ -211,6 +211,7 @@
#define I82579_MSE_THRESHOLD 0x084F /* 82579 Mean Square Error Threshold */
#define I82577_MSE_THRESHOLD 0x0887 /* 82577 Mean Square Error Threshold */
#define I82579_MSE_LINK_DOWN 0x2411 /* MSE count before dropping link */
+#define I82579_RX_CONFIG 0x3412 /* Receive configuration */
#define I82579_EEE_PCS_STATUS 0x182D /* IEEE MMD Register 3.1 >> 8 */
#define I82579_EEE_CAPABILITY 0x0410 /* IEEE MMD Register 3.20 */
#define I82579_EEE_ADVERTISEMENT 0x040E /* IEEE MMD Register 7.60 */