Re: [PATCH v4] wifi: wilc1000: add back-off algorithm to balance tx queue packets

[<Ajay.Kathat@microchip.com>]

On 9/15/23 11:00, Prasurjya Rohan saikia - I73664 wrote:
> 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>

Acked-by: Ajay Singh <ajay.kathat@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)
>  
>  	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);
>  
> @@ -166,12 +166,24 @@ static int wilc_txq_task(void *vp)
>  				srcu_idx = 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 == WILC_VMM_ENTRY_FULL_RETRY && !wl->close);
> +			if (ret != 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
>  
> +#define TX_BACKOFF_WEIGHT_MS			1
> +
>  struct wilc_wfi_stats {
>  	unsigned long rx_packets;
>  	unsigned long tx_packets;