Commit 6b51f802 authored by Alex Elder's avatar Alex Elder Committed by David S. Miller
Browse files

net: ipa: ensure hardware has power in ipa_start_xmit() 



We need to ensure the hardware is powered when we transmit a packet.
But if it's not, we can't block to wait for it.  So asynchronously
request power in ipa_start_xmit(), and only proceed if the return
value indicates the power state is active.

If the hardware is not active, a runtime resume request will have
been initiated.  In that case, stop the network stack from further
transmit attempts until the resume completes.  Return NETDEV_TX_BUSY,
to retry sending the packet once the queue is restarted.

If the power request returns an error (other than -EINPROGRESS,
which just means a resume requested elsewhere isn't complete), just
drop the packet.

Signed-off-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a96e73fa

drivers/net/ipa/ipa_modem.c

+29 −1
Original line number Diff line number Diff line
@@ -106,6 +106,7 @@ static int ipa_start_xmit(struct sk_buff *skb, struct net_device *netdev) 
	struct ipa_endpoint *endpoint;

	struct ipa *ipa = priv->ipa;

	u32 skb_len = skb->len;

	struct device *dev;

	int ret;



	if (!skb_len)
@@ -115,7 +116,31 @@ static int ipa_start_xmit(struct sk_buff *skb, struct net_device *netdev) 
	if (endpoint->data->qmap && skb->protocol != htons(ETH_P_MAP))

		goto err_drop_skb;



	/* The hardware must be powered for us to transmit */

	dev = &ipa->pdev->dev;

	ret = pm_runtime_get(dev);

	if (ret < 1) {

		/* If a resume won't happen, just drop the packet */

		if (ret < 0 && ret != -EINPROGRESS) {

			pm_runtime_put_noidle(dev);

			goto err_drop_skb;

		}



		/* No power (yet).  Stop the network stack from transmitting

		 * until we're resumed; ipa_modem_resume() arranges for the

		 * TX queue to be started again.

		 */

		netif_stop_queue(netdev);



		(void)pm_runtime_put(dev);



		return NETDEV_TX_BUSY;

	}



	ret = ipa_endpoint_skb_tx(endpoint, skb);



	(void)pm_runtime_put(dev);



	if (ret) {

		if (ret != -E2BIG)

			return NETDEV_TX_BUSY;
@@ -201,7 +226,10 @@ void ipa_modem_suspend(struct net_device *netdev) 
 *

 * Re-enable transmit on the modem network device.  This is called

 * in (power management) work queue context, scheduled when resuming

 * the modem.

 * the modem.  We can't enable the queue directly in ipa_modem_resume()

 * because transmits restart the instant the queue is awakened; but the

 * device power state won't be ACTIVE until *after* ipa_modem_resume()

 * returns.

 */

static void ipa_modem_wake_queue_work(struct work_struct *work)

{