[PATCH net 2/2] igc: Modify the tx-usecs coalesce setting

[Tony Nguyen <anthony.l.nguyen@intel.com>]

From: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@intel.com>

This patch enables users to modify the tx-usecs parameter.
The rx-usecs value will adhere to the same value as tx-usecs
if the queue pair setting is enabled.

How to test:
User can set the coalesce value using ethtool command.

Example command:
Set: ethtool -C <interface>

Previous output:

root@P12DYHUSAINI:~# ethtool -C enp170s0 tx-usecs 10
netlink error: Invalid argument

New output:

root@P12DYHUSAINI:~# ethtool -C enp170s0 tx-usecs 10
rx-usecs: 10
rx-frames: n/a
rx-usecs-irq: n/a
rx-frames-irq: n/a

tx-usecs: 10
tx-frames: n/a
tx-usecs-irq: n/a
tx-frames-irq: n/a

Fixes: 8c5ad0dae93c ("igc: Add ethtool support")
Signed-off-by: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@intel.com>
Tested-by: Naama Meir <naamax.meir@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/igc/igc_ethtool.c | 33 ++++++++++++++++++--
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_ethtool.c b/drivers/net/ethernet/intel/igc/igc_ethtool.c
index 62d925b26f2c..1cf7131a82c5 100644
--- a/drivers/net/ethernet/intel/igc/igc_ethtool.c
+++ b/drivers/net/ethernet/intel/igc/igc_ethtool.c
@@ -914,6 +914,34 @@ static int igc_ethtool_set_coalesce(struct net_device *netdev,
 			adapter->flags &= ~IGC_FLAG_DMAC;
 	}
 
+	if (adapter->flags & IGC_FLAG_QUEUE_PAIRS) {
+		u32 old_tx_itr, old_rx_itr;
+
+		/* This is to get back the original value before byte shifting */
+		old_tx_itr = (adapter->tx_itr_setting <= 3) ?
+			      adapter->tx_itr_setting : adapter->tx_itr_setting >> 2;
+
+		old_rx_itr = (adapter->rx_itr_setting <= 3) ?
+			      adapter->rx_itr_setting : adapter->rx_itr_setting >> 2;
+
+		if (old_tx_itr != ec->tx_coalesce_usecs) {
+			if (ec->tx_coalesce_usecs && ec->tx_coalesce_usecs <= 3)
+				adapter->tx_itr_setting = ec->tx_coalesce_usecs;
+			else
+				adapter->tx_itr_setting = ec->tx_coalesce_usecs << 2;
+
+			adapter->rx_itr_setting = adapter->tx_itr_setting;
+		} else if (old_rx_itr != ec->rx_coalesce_usecs) {
+			if (ec->rx_coalesce_usecs && ec->rx_coalesce_usecs <= 3)
+				adapter->rx_itr_setting = ec->rx_coalesce_usecs;
+			else
+				adapter->rx_itr_setting = ec->rx_coalesce_usecs << 2;
+
+			adapter->tx_itr_setting = adapter->rx_itr_setting;
+		}
+		goto program_itr;
+	}
+
 	/* convert to rate of irq's per second */
 	if (ec->rx_coalesce_usecs && ec->rx_coalesce_usecs <= 3)
 		adapter->rx_itr_setting = ec->rx_coalesce_usecs;
@@ -921,13 +949,12 @@ static int igc_ethtool_set_coalesce(struct net_device *netdev,
 		adapter->rx_itr_setting = ec->rx_coalesce_usecs << 2;
 
 	/* convert to rate of irq's per second */
-	if (adapter->flags & IGC_FLAG_QUEUE_PAIRS)
-		adapter->tx_itr_setting = adapter->rx_itr_setting;
-	else if (ec->tx_coalesce_usecs && ec->tx_coalesce_usecs <= 3)
+	if (ec->tx_coalesce_usecs && ec->tx_coalesce_usecs <= 3)
 		adapter->tx_itr_setting = ec->tx_coalesce_usecs;
 	else
 		adapter->tx_itr_setting = ec->tx_coalesce_usecs << 2;
 
+program_itr:
 	for (i = 0; i < adapter->num_q_vectors; i++) {
 		struct igc_q_vector *q_vector = adapter->q_vector[i];
 
-- 
2.38.1