Revert "mvebu: remove linux 4.4 support"

This reverts commit 51397d7d95d9f5e210a5557f65de1fa21e6f5921.
There are some unresolved random crashes on WRT1900AC v1 that still need
to be sorted out

Signed-off-by: Felix Fietkau <nbd@nbd.name>

1 files changed, 36 insertions, 0 deletions

diff --git a/target/linux/mvebu/patches-4.4/400-mvneta-tx-queue-workaround.patch b/target/linux/mvebu/patches-4.4/400-mvneta-tx-queue-workaround.patch
new file mode 100644
index 0000000000..5dba311d93
--- /dev/null
+++ b/target/linux/mvebu/patches-4.4/400-mvneta-tx-queue-workaround.patch
@@ -0,0 +1,36 @@
+The hardware queue scheduling is apparently configured with fixed
+priorities, which creates a nasty fairness issue where traffic from one
+CPU can starve traffic from all other CPUs.
+
+Work around this issue by forcing all tx packets to go through one CPU,
+until this issue is fixed properly.
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+--- a/drivers/net/ethernet/marvell/mvneta.c
++++ b/drivers/net/ethernet/marvell/mvneta.c
+@@ -3984,6 +3984,16 @@ static int mvneta_ethtool_set_eee(struct
+ 	return phylink_ethtool_set_eee(pp->phylink, eee);
+ }
+ 
++static u16 mvneta_select_queue(struct net_device *dev, struct sk_buff *skb,
++			       void *accel_priv,
++			       select_queue_fallback_t fallback)
++{
++	/* XXX: hardware queue scheduling is broken,
++	 * use only one queue until it is fixed */
++	return 0;
++}
++
++
+ static const struct net_device_ops mvneta_netdev_ops = {
+ 	.ndo_open            = mvneta_open,
+ 	.ndo_stop            = mvneta_stop,
+@@ -3994,6 +4004,7 @@ static const struct net_device_ops mvnet
+ 	.ndo_fix_features    = mvneta_fix_features,
+ 	.ndo_get_stats64     = mvneta_get_stats64,
+ 	.ndo_do_ioctl        = mvneta_ioctl,
++	.ndo_select_queue    = mvneta_select_queue,
+ };
+ 
+ const struct ethtool_ops mvneta_eth_tool_ops = {