[PATCH v4 01/15] docs: phy: Add a part about PHY mode and submode

[Paul Kocialkowski]

Besides giving pointers to the relevant functions for PHY mode and
submode configuration, this clarifies the need to set them before
powering on the PHY.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski at bootlin.com>
Reviewed-by: Maxime Ripard <mripard at kernel.org>
---
 Documentation/driver-api/phy/phy.rst | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Documentation/driver-api/phy/phy.rst b/Documentation/driver-api/phy/phy.rst
index 8fc1ce0bb905..6cbc72707a49 100644
--- a/Documentation/driver-api/phy/phy.rst
+++ b/Documentation/driver-api/phy/phy.rst
@@ -195,3 +195,21 @@ DeviceTree Binding
 
 The documentation for PHY dt binding can be found @
 Documentation/devicetree/bindings/phy/phy-bindings.txt
+
+PHY Mode and Submode
+====================
+
+Once a reference to a PHY is obtained by a controller, the PHY can be configured
+to a PHY mode and submode. PHY modes are described in the `phy_mode` enum while
+submodes are specific to the selected PHY mode.
+
+Mode and submode configuration is done by calling::
+
+	int phy_set_mode_ext(struct phy *phy, enum phy_mode mode, int submode);
+
+If no submode is to be configured, users can call::
+
+	int phy_set_mode(struct phy *phy, enum phy_mode mode);
+
+The PHY mode and submode must not be configured after the PHY has already been
+powered on.
-- 
2.29.2