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

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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: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alex Elder 2021-08-12 14:50:33 -05:00 committed by David S. Miller
parent a96e73fa12
commit 6b51f802d6
1 changed files with 29 additions and 1 deletions
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30
drivers/net/ipa/ipa_modem.c
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@ -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)
{