media: field-order.rst: clarify FIELD_ANY and FIELD_NONE

Rephrased the FIELD_ANY description: rather than explicitly list
field values, just say 'when any field format is acceptable'. The
list of FIELD values was outdated, so it was a bit confusing.

The FIELD_NONE description said that 'The driver may also indicate
this order when it cannot distinguish between V4L2_FIELD_TOP and
V4L2_FIELD_BOTTOM'. This is false, NONE really means a full frame
and userspace depends on that. So drop this line completely. There
are no drivers that do this anyway.

FIELD_TOP/BOTTOM/ALTERNATE indicate that the number of lines in the
buffer are that of a field, not frame, so returning NONE here would
cause huge problems.

Finally attempt to clarify 'progressive' and 'interlaced' a little
bit.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

diff --git a/Documentation/media/uapi/v4l/field-order.rst b/Documentation/media/uapi/v4l/field-order.rst
index 3fb473e3b8e2e205d4e0d6692a891d560eec3781..d640e922a9748c795ec670f4375098372052f6dd 100644 (file)
--- a/Documentation/media/uapi/v4l/field-order.rst
+++ b/Documentation/media/uapi/v4l/field-order.rst
@@ -75,12 +75,11 @@ enum v4l2_field
 
     * - ``V4L2_FIELD_ANY``
       - 0
-      - Applications request this field order when any one of the
-       ``V4L2_FIELD_NONE``, ``V4L2_FIELD_TOP``, ``V4L2_FIELD_BOTTOM``, or
-       ``V4L2_FIELD_INTERLACED`` formats is acceptable. Drivers choose
-       depending on hardware capabilities or e. g. the requested image
-       size, and return the actual field order. Drivers must never return
-       ``V4L2_FIELD_ANY``. If multiple field orders are possible the
+      - Applications request this field order when any field format
+       is acceptable. Drivers choose depending on hardware capabilities or
+       e.g. the requested image size, and return the actual field order.
+       Drivers must never return ``V4L2_FIELD_ANY``.
+       If multiple field orders are possible the
        driver must choose one of the possible field orders during
        :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` or
        :ref:`VIDIOC_TRY_FMT <VIDIOC_G_FMT>`. struct
@@ -88,9 +87,8 @@ enum v4l2_field
        ``V4L2_FIELD_ANY``.
     * - ``V4L2_FIELD_NONE``
       - 1
-      - Images are in progressive format, not interlaced. The driver may
-       also indicate this order when it cannot distinguish between
-       ``V4L2_FIELD_TOP`` and ``V4L2_FIELD_BOTTOM``.
+      - Images are in progressive (frame-based) format, not interlaced
+        (field-based).
     * - ``V4L2_FIELD_TOP``
       - 2
       - Images consist of the top (aka odd) field only.