netdev - [PATCH iwl-net v4 2/2] igc: Modify the tx-usecs coalesce setting

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Date: Sat, 19 Aug 2023 21:50:51 +0800
From: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@...el.com>
To: intel-wired-lan@...osl.org
Cc: sasha.neftin@...el.com,
	bcreeley@....com,
	horms@...nel.org,
	davem@...emloft.net,
	kuba@...nel.org,
	muhammad.husaini.zulkifli@...el.com,
	pabeni@...hat.com,
	edumazet@...gle.com,
	netdev@...r.kernel.org,
	naamax.meir@...ux.intel.com,
	anthony.l.nguyen@...el.com
Subject: [PATCH iwl-net v4 2/2] igc: Modify the tx-usecs coalesce setting

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@...DYHUSAINI:~# ethtool -C enp170s0 tx-usecs 10
netlink error: Invalid argument

New output:

root@...DYHUSAINI:~# 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@...el.com>
Tested-by: Naama Meir <naamax.meir@...ux.intel.com>
---
 drivers/net/ethernet/intel/igc/igc_ethtool.c | 45 ++++++++++++++------
 1 file changed, 33 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_ethtool.c b/drivers/net/ethernet/intel/igc/igc_ethtool.c
index 62d925b26f2c..40ec6ebc0843 100644
--- a/drivers/net/ethernet/intel/igc/igc_ethtool.c
+++ b/drivers/net/ethernet/intel/igc/igc_ethtool.c
@@ -888,6 +888,11 @@ static int igc_ethtool_get_coalesce(struct net_device *netdev,
 	return 0;
 }
 
+static int igc_ethtool_coalesce_to_itr_setting(u32 coalesce_usecs)
+{
+	return coalesce_usecs <= 3 ? coalesce_usecs : coalesce_usecs << 2;
+}
+
 static int igc_ethtool_set_coalesce(struct net_device *netdev,
 				    struct ethtool_coalesce *ec,
 				    struct kernel_ethtool_coalesce *kernel_coal,
@@ -914,19 +919,35 @@ static int igc_ethtool_set_coalesce(struct net_device *netdev,
 			adapter->flags &= ~IGC_FLAG_DMAC;
 	}
 
-	/* 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;
-	else
-		adapter->rx_itr_setting = ec->rx_coalesce_usecs << 2;
+	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;
+
+		/* convert to rate of irq's per second */
+		if (old_tx_itr != ec->tx_coalesce_usecs) {
+			adapter->tx_itr_setting =
+				igc_ethtool_coalesce_to_itr_setting(ec->tx_coalesce_usecs);
+			adapter->rx_itr_setting = adapter->tx_itr_setting;
+		} else if (old_rx_itr != ec->rx_coalesce_usecs) {
+			adapter->rx_itr_setting =
+				igc_ethtool_coalesce_to_itr_setting(ec->rx_coalesce_usecs);
+			adapter->tx_itr_setting = adapter->rx_itr_setting;
+		}
+	} else {
+		/* convert to rate of irq's per second */
+		adapter->rx_itr_setting =
+			igc_ethtool_coalesce_to_itr_setting(ec->rx_coalesce_usecs);
 
-	/* 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)
-		adapter->tx_itr_setting = ec->tx_coalesce_usecs;
-	else
-		adapter->tx_itr_setting = ec->tx_coalesce_usecs << 2;
+		/* convert to rate of irq's per second */
+		adapter->tx_itr_setting =
+			igc_ethtool_coalesce_to_itr_setting(ec->tx_coalesce_usecs);
+	}
 
 	for (i = 0; i < adapter->num_q_vectors; i++) {
 		struct igc_q_vector *q_vector = adapter->q_vector[i];
-- 
2.17.1