[RFC v3 9/9] media: Documentation: Add binning and sub-sampling controls

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Document the binning and scaling controls (V4L2_CID_BINNING and
V4L2_CID_SUBSAMPLING_{HORIZONTAL,VERTICAL}) in the common raw sensor
model.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 .../media/v4l/subdev-config-model.rst           | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/Documentation/userspace-api/media/v4l/subdev-config-model.rst b/Documentation/userspace-api/media/v4l/subdev-config-model.rst
index 1ae20800f34b..06a94ff4d2b4 100644
--- a/Documentation/userspace-api/media/v4l/subdev-config-model.rst
+++ b/Documentation/userspace-api/media/v4l/subdev-config-model.rst
@@ -113,7 +113,10 @@ separately horizontally and vertically.
 Binning and sub-sampling are configured using the ``V4L2_SEL_TGT_COMPOSE``
 rectangle, relative to the analogue crop rectangle, on (pad, stream) pair
 1/0. It depends on the driver which of these operations are being used to
-achieve the resulting size.
+achieve the resulting size. Binning and sub-sampling are also directly
+configured using :ref:`V4L2_CID_BINNING <v4l2-cid-camera-sensor-binning>` and
+:ref:`V4L2_CID_SUBSAMPLING_HORIZONTAL and V4L2_CID_SUBSAMPLING_VERTICAL
+<v4l2-cid-camera-sensor-subsampling>` controls on drivers that support them.
 
 The digital crop operation takes place after binning and sub-sampling. It is
 configured by setting the ``V4L2_SEL_TGT_CROP`` rectangle on (pad, stream) pair
@@ -169,9 +172,15 @@ Also refer to :ref:`Selection targets <v4l2-selection-targets-table>`.
       - \-
       - X
       - Binning and sub-sampling. This rectangle is relative to the
-        ``V4L2_SEL_TGT_CROP`` rectangle on the same (pad, stream). The
-        combination of binning and sub-sampling is configured using this
-        selection target.
+        ``V4L2_SEL_TGT_CROP`` rectangle on the same (pad, stream). Binning is
+        configured using the :ref:`V4L2_CID_BINNING
+        <v4l2-cid-camera-sensor-binning>` control and sub-sampling is configured
+        using the :ref:`V4L2_CID_SUBSAMPLING_HORIZONTAL and
+        V4L2_CID_SUBSAMPLING_VERTICAL <v4l2-cid-camera-sensor-subsampling>`
+        controls on drivers that support these controls. To configure binning
+        and sub-sampling on drivers that do not support these controls, the
+        selection rectangle may be changed directly to configure the combined
+        effect on the image size.
     * - 2/0
       - Format
       - X
-- 
2.39.5