[PATCH net 2/4] docs: net: dsa: update platform_data documentation

[Vladimir Oltean <vladimir.oltean@nxp.com>]

We were documenting a bunch of stuff which was removed in commit
93e86b3bc842 ("net: dsa: Remove legacy probing support"). There's some
further cleanup to do in struct dsa_chip_data, so rather than describing
every possible field (when maybe we should be switching to kerneldoc
format), just say what's important about it.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 Documentation/networking/dsa/dsa.rst | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/Documentation/networking/dsa/dsa.rst b/Documentation/networking/dsa/dsa.rst
index 0c326a42eb81..676c92136a0e 100644
--- a/Documentation/networking/dsa/dsa.rst
+++ b/Documentation/networking/dsa/dsa.rst
@@ -413,18 +413,17 @@ PHYs, external PHYs, or even external switches.
 Data structures
 ---------------
 
-DSA data structures are defined in ``include/net/dsa.h`` as well as
-``net/dsa/dsa_priv.h``:
-
-- ``dsa_chip_data``: platform data configuration for a given switch device,
-  this structure describes a switch device's parent device, its address, as
-  well as various properties of its ports: names/labels, and finally a routing
-  table indication (when cascading switches)
-
-- ``dsa_platform_data``: platform device configuration data which can reference
-  a collection of dsa_chip_data structures if multiple switches are cascaded,
-  the conduit network device this switch tree is attached to needs to be
-  referenced
+DSA data structures are defined in ``include/linux/platform_data/dsa.h``,
+``include/net/dsa.h`` as well as ``net/dsa/dsa_priv.h``:
+
+- ``dsa_chip_data``: platform data configuration for a given switch device.
+  Most notably, it is necessary to the DSA core because it holds a reference to
+  the conduit interface. It must be accessible through the
+  ``ds->dev->platform_data`` pointer at ``dsa_register_switch()`` time. It is
+  populated by board-specific code. The hardware switch driver may also have
+  its own portion of ``platform_data`` description. In that case,
+  ``ds->dev->platform_data`` can point to a switch-specific structure, which
+  encapsulates ``struct dsa_chip_data`` as its first element.
 
 - ``dsa_switch_tree``: structure assigned to the conduit network device under
   ``dsa_ptr``, this structure references a dsa_platform_data structure as well as
-- 
2.34.1