[PATCH iwl-next,v1 3/3] igc: Add default Rx Queue into documentation

[Song Yoong Siang]

From: Blanco Alcaine Hector <hector.blanco.alcaine@xxxxxxxxx>

Add description on default Rx Queue, including the get and set
method, into documentation.

Signed-off-by: Blanco Alcaine Hector <hector.blanco.alcaine@xxxxxxxxx>
Signed-off-by: Song Yoong Siang <yoong.siang.song@xxxxxxxxx>
---
 .../device_drivers/ethernet/intel/igc.rst     | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Documentation/networking/device_drivers/ethernet/intel/igc.rst b/Documentation/networking/device_drivers/ethernet/intel/igc.rst
index 08b2cfacc7c0..bef396d9ec53 100644
--- a/Documentation/networking/device_drivers/ethernet/intel/igc.rst
+++ b/Documentation/networking/device_drivers/ethernet/intel/igc.rst
@@ -63,6 +63,27 @@ diagnostics, as well as displaying statistical information. The latest ethtool
 version is required for this functionality. Download it at:
 https://www.kernel.org/pub/software/network/ethtool/
 
+Default Rx queue selection
+--------------------------
+In Multiple Receive Queues modes, ingress traffic may be redirected to specific
+Rx queue based on different programmable filters.
+
+When none of the filters is matched, the incoming frame will be redirected to
+the "Default Rx queue", which is Rx Queue 0 by default.
+
+For configurations where Queue 0 pair is used for high priority traffic (like
+AF_XDP), this may not be desirable. To address this, the driver provides the
+option to modify the default Rx queue via sysfs.
+
+A sysfs attribute "default_rx_queue" is available under /sys/devices. E.g.:
+/sys/devices/pci0000:00/.../default_rx_queue
+
+To check the currently configured default Rx queue:
+cat /sys/devices/pci0000:00/.../default_rx_queue
+
+To set the default queue to a desired value, for example 3:
+echo 3 > /sys/devices/pci0000:00/.../default_rx_queue
+
 
 Support
 =======
-- 
2.34.1