[PATCH v3 2/7] dt-bindings: net: dsa: mediatek,mt7530: add passthrough mode

[Caleb James DeLisle <cjd@cjdns.fr>]

MT7530 switches can be configured to blindly pass packets between their
CPU/upstream port and a downstream DSA port, in particular, without
altering the MediaTek DSA Tag on the packets. This mode is used in some
integrations where an SoC integrated switch exists, but a more capable
MCM switch is added to effectively replace it.

Signed-off-by: Caleb James DeLisle <cjd@cjdns.fr>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
---
 .../devicetree/bindings/net/dsa/mediatek,mt7530.yaml       | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml b/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml
index 90b3582b7619..e29fb8693498 100644
--- a/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml
+++ b/Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml
@@ -73,6 +73,13 @@ description: |
 
       Check out example 7.
 
+  The MT7530 and MT7531 switches are capable of being operated in "passthrough"
+  mode. In this mode, traffic is unconditionally passed between the CPU port
+  and the DSA port which links to a second switch. To use passthrough mode, the
+  upstream switch is configured with a DSA link to the downstream switch. In
+  passthrough mode the upstream switch is restricted, with no other ports or
+  switch configuration allowed.
+
 properties:
   compatible:
     oneOf:
-- 
2.39.5