Re: [PATCH] libertas: detect TX lockups and reset hardware

[Dan Williams <dcbw@redhat.com>]

On Wed, 2011-09-21 at 16:30 +0100, Daniel Drake wrote:
> Recent patches added support for resetting the SD8686 hardware when
> commands time out, which seems to happen quite frequently soon after
> resuming the system from a Wake-on-WLAN-triggered resume.
> 
> At http://dev.laptop.org/ticket/10969 we see the same thing happen
> with transmits. In this case, the hardware will fail to respond to
> a frame passed for transmission, and libertas (correctly) will block
> all further commands and transmissions as the hardware can only
> deal with one thing at a time. This results in a lockup while the
> system waits indefinitely for the dead card to respond.
> 
> Hook up a TX lockup timer to detect this and reset the hardware.

Acked-by: Dan Williams <dcbw@redhat.com>


> Signed-off-by: Daniel Drake <dsd@laptop.org>
> ---
>  drivers/net/wireless/libertas/dev.h  |    1 +
>  drivers/net/wireless/libertas/main.c |   35 ++++++++++++++++++++++++++++++++++
>  2 files changed, 36 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/net/wireless/libertas/dev.h b/drivers/net/wireless/libertas/dev.h
> index adb3490..7487b5e 100644
> --- a/drivers/net/wireless/libertas/dev.h
> +++ b/drivers/net/wireless/libertas/dev.h
> @@ -146,6 +146,7 @@ struct lbs_private {
>  	/* protected by hard_start_xmit serialization */
>  	u8 txretrycount;
>  	struct sk_buff *currenttxskb;
> +	struct timer_list tx_lockup_timer;
>  
>  	/* Locks */
>  	struct mutex lock;
> diff --git a/drivers/net/wireless/libertas/main.c b/drivers/net/wireless/libertas/main.c
> index 94652c5..5aabe8f 100644
> --- a/drivers/net/wireless/libertas/main.c
> +++ b/drivers/net/wireless/libertas/main.c
> @@ -163,6 +163,7 @@ void lbs_host_to_card_done(struct lbs_private *priv)
>  	lbs_deb_enter(LBS_DEB_THREAD);
>  
>  	spin_lock_irqsave(&priv->driver_lock, flags);
> +	del_timer(&priv->tx_lockup_timer);
>  
>  	priv->dnld_sent = DNLD_RES_RECEIVED;
>  
> @@ -504,6 +505,9 @@ static int lbs_thread(void *data)
>  			if (ret) {
>  				lbs_deb_tx("host_to_card failed %d\n", ret);
>  				priv->dnld_sent = DNLD_RES_RECEIVED;
> +			} else {
> +				mod_timer(&priv->tx_lockup_timer,
> +					  jiffies + (HZ * 5));
>  			}
>  			priv->tx_pending_len = 0;
>  			if (!priv->currenttxskb) {
> @@ -520,6 +524,7 @@ static int lbs_thread(void *data)
>  	}
>  
>  	del_timer(&priv->command_timer);
> +	del_timer(&priv->tx_lockup_timer);
>  	del_timer(&priv->auto_deepsleep_timer);
>  
>  	lbs_deb_leave(LBS_DEB_THREAD);
> @@ -654,6 +659,32 @@ out:
>  }
>  
>  /**
> + * lbs_tx_lockup_handler - handles the timeout of the passing of TX frames
> + * to the hardware. This is known to frequently happen with SD8686 when
> + * waking up after a Wake-on-WLAN-triggered resume.
> + *
> + * @data: &struct lbs_private pointer
> + */
> +static void lbs_tx_lockup_handler(unsigned long data)
> +{
> +	struct lbs_private *priv = (struct lbs_private *)data;
> +	unsigned long flags;
> +
> +	lbs_deb_enter(LBS_DEB_TX);
> +	spin_lock_irqsave(&priv->driver_lock, flags);
> +
> +	netdev_info(priv->dev, "TX lockup detected\n");
> +	if (priv->reset_card)
> +		priv->reset_card(priv);
> +
> +	priv->dnld_sent = DNLD_RES_RECEIVED;
> +	wake_up_interruptible(&priv->waitq);
> +
> +	spin_unlock_irqrestore(&priv->driver_lock, flags);
> +	lbs_deb_leave(LBS_DEB_TX);
> +}
> +
> +/**
>   * auto_deepsleep_timer_fn - put the device back to deep sleep mode when
>   * timer expires and no activity (command, event, data etc.) is detected.
>   * @data:	&struct lbs_private pointer
> @@ -739,6 +770,8 @@ static int lbs_init_adapter(struct lbs_private *priv)
>  
>  	setup_timer(&priv->command_timer, lbs_cmd_timeout_handler,
>  		(unsigned long)priv);
> +	setup_timer(&priv->tx_lockup_timer, lbs_tx_lockup_handler,
> +		(unsigned long)priv);
>  	setup_timer(&priv->auto_deepsleep_timer, auto_deepsleep_timer_fn,
>  			(unsigned long)priv);
>  
> @@ -776,6 +809,7 @@ static void lbs_free_adapter(struct lbs_private *priv)
>  	lbs_free_cmd_buffer(priv);
>  	kfifo_free(&priv->event_fifo);
>  	del_timer(&priv->command_timer);
> +	del_timer(&priv->tx_lockup_timer);
>  	del_timer(&priv->auto_deepsleep_timer);
>  
>  	lbs_deb_leave(LBS_DEB_MAIN);
> @@ -995,6 +1029,7 @@ void lbs_stop_card(struct lbs_private *priv)
>  
>  	/* Delete the timeout of the currently processing command */
>  	del_timer_sync(&priv->command_timer);
> +	del_timer_sync(&priv->tx_lockup_timer);
>  	del_timer_sync(&priv->auto_deepsleep_timer);
>  
>  	/* Flush pending command nodes */