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From:   <Prasurjya.Rohansaikia@microchip.com>
To:     <linux-wireless@vger.kernel.org>
CC:     <Ajay.Kathat@microchip.com>, <claudiu.beznea@microchip.com>
Subject: [PATCH v4] wifi: wilc1000: add back-off algorithm to balance tx queue
 packets
Thread-Topic: [PATCH v4] wifi: wilc1000: add back-off algorithm to balance tx
 queue packets
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Date:   Fri, 15 Sep 2023 18:00:40 +0000
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From: Prasurjya Rohan Saikia <prasurjya.rohansaikia@microchip.com>

Add an algorithm to backoff the Tx Task when low memory scenario is
triggered at firmware. During high data transfer from host, the firmware
runs out of VMM memory, which is used to hold the frames from the host.
So, adding the flow control delays the transmit from host side when
there is not enough space to accommodate frames in firmware side.

Signed-off-by: Prasurjya Rohan Saikia <prasurjya.rohansaikia@microchip.com>
---
v3 -> v4: As per review comments, replaced
schedule_timeout_interruptible() by msleep_interruptible().

v2 -> v3: Replaced schedule_timeout() by
schedule_timeout_interruptible().

v1 -> v2: Removed the unused `timeout` variable.
---
 .../net/wireless/microchip/wilc1000/netdev.c  | 20 +++++++++++++++----
 .../net/wireless/microchip/wilc1000/netdev.h  |  2 ++
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/microchip/wilc1000/netdev.c b/drivers/net=
/wireless/microchip/wilc1000/netdev.c
index e9f59de31b0b..91d71e0f7ef2 100644
--- a/drivers/net/wireless/microchip/wilc1000/netdev.c
+++ b/drivers/net/wireless/microchip/wilc1000/netdev.c
@@ -148,8 +148,8 @@ static int wilc_txq_task(void *vp)
=20
 	complete(&wl->txq_thread_started);
 	while (1) {
-		wait_for_completion(&wl->txq_event);
-
+		if (wait_for_completion_interruptible(&wl->txq_event))
+			continue;
 		if (wl->close) {
 			complete(&wl->txq_thread_started);
=20
@@ -166,12 +166,24 @@ static int wilc_txq_task(void *vp)
 				srcu_idx =3D srcu_read_lock(&wl->srcu);
 				list_for_each_entry_rcu(ifc, &wl->vif_list,
 							list) {
-					if (ifc->mac_opened && ifc->ndev)
+					if (ifc->mac_opened &&
+					    netif_queue_stopped(ifc->ndev))
 						netif_wake_queue(ifc->ndev);
 				}
 				srcu_read_unlock(&wl->srcu, srcu_idx);
 			}
-		} while (ret =3D=3D WILC_VMM_ENTRY_FULL_RETRY && !wl->close);
+			if (ret !=3D WILC_VMM_ENTRY_FULL_RETRY)
+				break;
+			/* Back off TX task from sending packets for some time.
+			 * msleep_interruptible will allow RX task to run and
+			 * free buffers. TX task will be in TASK_INTERRUPTIBLE
+			 * state which will put the thread back to CPU running
+			 * queue when it's signaled even if the timeout isn't
+			 * elapsed. This gives faster chance for reserved SK
+			 * buffers to be free.
+			 */
+			msleep_interruptible(TX_BACKOFF_WEIGHT_MS);
+		} while (!wl->close);
 	}
 	return 0;
 }
diff --git a/drivers/net/wireless/microchip/wilc1000/netdev.h b/drivers/net=
/wireless/microchip/wilc1000/netdev.h
index bb1a315a7b7e..aafe3dc44ac6 100644
--- a/drivers/net/wireless/microchip/wilc1000/netdev.h
+++ b/drivers/net/wireless/microchip/wilc1000/netdev.h
@@ -27,6 +27,8 @@
 #define TCP_ACK_FILTER_LINK_SPEED_THRESH	54
 #define DEFAULT_LINK_SPEED			72
=20
+#define TX_BACKOFF_WEIGHT_MS			1
+
 struct wilc_wfi_stats {
 	unsigned long rx_packets;
 	unsigned long tx_packets;
--=20
2.34.1