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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] wifi: wilc1000: Added back-off algorithm to balance tx queue
 packets.
Thread-Topic: [PATCH] wifi: wilc1000: Added back-off algorithm to balance tx
 queue packets.
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Date:   Thu, 10 Aug 2023 18:46:34 +0000
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From: Prasurjya Rohan Saikia <prasurjya.rohansaikia@microchip.com>

Added 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 added flow control to delay the transmit from host side when there is
not enough space to accomodate frames in firmware side.

Signed-off-by: Prasurjya Rohan Saikia <prasurjya.rohansaikia@microchip.com>
---
 .../net/wireless/microchip/wilc1000/netdev.c  | 19 ++++++++++++++++---
 .../net/wireless/microchip/wilc1000/netdev.h  |  2 ++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/microchip/wilc1000/netdev.c b/drivers/net=
/wireless/microchip/wilc1000/netdev.c
index e9f59de31b0b..40b34490f6ef 100644
--- a/drivers/net/wireless/microchip/wilc1000/netdev.c
+++ b/drivers/net/wireless/microchip/wilc1000/netdev.c
@@ -144,12 +144,13 @@ static int wilc_txq_task(void *vp)
 {
 	int ret;
 	u32 txq_count;
+	signed long timeout;
 	struct wilc *wl =3D 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
@@ -166,11 +167,23 @@ 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);
 			}
+			if (ret !=3D WILC_VMM_ENTRY_FULL_RETRY)
+				break;
+			/* Back off from sending packets for some time.
+			 * schedule_timeout will allow RX task to run and free
+			 * buffers. Setting state to TASK_INTERRUPTIBLE will
+			 * put the thread back to CPU running queue when it's
+			 * signaled even if 'timeout' isn't elapsed. This gives
+			 * faster chance for reserved SK buffers to be freed
+			 */
+			set_current_state(TASK_INTERRUPTIBLE);
+			timeout =3D schedule_timeout(msecs_to_jiffies(TX_BACKOFF_WEIGHT_MS));
 		} while (ret =3D=3D WILC_VMM_ENTRY_FULL_RETRY && !wl->close);
 	}
 	return 0;
diff --git a/drivers/net/wireless/microchip/wilc1000/netdev.h b/drivers/net=
/wireless/microchip/wilc1000/netdev.h
index bb1a315a7b7e..380ad38ecb64 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