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authorAlex Elder <elder@linaro.org>2021-08-12 22:50:33 +0300
committerDavid S. Miller <davem@davemloft.net>2021-08-14 16:13:38 +0300
commit6b51f802d652b9f053ef5103dc33b7a55c67860c (patch)
treebee40e8521ced6e76e50df99f1c517777af72fcf
parenta96e73fa1269a1d1b932f465ed0a803d4c153258 (diff)
downloadlinux-6b51f802d652b9f053ef5103dc33b7a55c67860c.tar.xz
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: Alex Elder <elder@linaro.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/ipa/ipa_modem.c30
1 files changed, 29 insertions, 1 deletions
diff --git a/drivers/net/ipa/ipa_modem.c b/drivers/net/ipa/ipa_modem.c
index 0a3b034614b6..aa1b483d9f7d 100644
--- a/drivers/net/ipa/ipa_modem.c
+++ b/drivers/net/ipa/ipa_modem.c
@@ -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)
{