net: airoha: defer GDM3/GDM4 WAN mode and GDM2 loopback to QoS offload

GDM3 and GDM4 ports require GDM2 loopback to be enabled for hardware
QoS offload to function. Without it, HTB and ETS offload on these ports
do not work.
Previously, GDM3/GDM4 ports were automatically configured as WAN with
GDM2 loopback enabled during ndo_init().
Add the capability to configure GDM3/GDM4 as WAN/LAN on demand when QoS
offload is created or destroyed.
Hook airoha_enable_qos_for_gdm34() into TC_HTB_CREATE so that requesting
HTB offload on a GDM3/GDM4 LAN port switches it to WAN mode and enables
GDM2 loopback.
Introduce the AIROHA_DEV_F_TX_QOS flag to track whether a device has an
active TX HTB qdisc; set it in airoha_tc_setup_qdisc_htb() on successful
TC_HTB_CREATE and clear it on TC_HTB_DESTROY. The device keeps its WAN
role after qdisc teardown so that its configuration is preserved until
another device explicitly needs the WAN role for QoS offload.
If another GDM3/GDM4 device already holds the WAN role without an active
TX qdisc, demote it to LAN before promoting the requesting device. Skip
the demotion when the requesting device is itself already the WAN device.
Since airoha_dev_set_qdma() can now be called on a running device to
migrate between QDMA blocks, make dev->qdma an RCU pointer so the TX path
can safely dereference it without holding RTNL.
When migrating between QDMA blocks, stop TX queues, swap the pointer via
rcu_assign_pointer(), then synchronize_rcu() to ensure no in-flight
ndo_start_xmit holds the old pointer.
Serialize netdev_tx_completed_queue() calls via per-TX-queue spinlocks
txq_lock[] so that both the old and new QDMA NAPI instances can complete
packets concurrently on the same netdev TX queues without racing on
dql_completed().
Hold flow_offload_mutex in airoha_enable_qos_for_gdm34() and
airoha_disable_qos_for_gdm34() around the dev->flags update,
airoha_dev_set_qdma() and GDM2 loopback configuration, serializing
against concurrent airoha_ppe_hw_init() in the TC_SETUP_CLSFLOWER
offload path.
Introduce airoha_qdma_deref() helper that wraps rcu_dereference_protected()
with a lockdep condition accepting either rtnl_lock or flow_offload_mutex,
and use it across all control-path dereferences of the RCU-protected
dev->qdma pointer.
Add airoha_disable_gdm2_loopback() to disable GDM2 hw loopback.

Tested-by: Madhur Agarwal <madhur.agrawal@airoha.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20260725-airoha-ethtool-priv_flags-v12-3-5136a30b2157@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

0 files changed, 0 insertions, 0 deletions