media: v4l2-subdev: Add which field to struct v4l2_subdev_frame_interval

Due to a historical mishap, the v4l2_subdev_frame_interval structure
is the only part of the V4L2 subdev userspace API that doesn't contain a
'which' field. This prevents trying frame intervals using the subdev
'TRY' state mechanism.

Adding a 'which' field is simple as the structure has 8 reserved fields.
This would however break userspace as the field is currently set to 0,
corresponding to V4L2_SUBDEV_FORMAT_TRY, while the corresponding ioctls
currently operate on the 'ACTIVE' state. We thus need to add a new
subdev client cap, V4L2_SUBDEV_CLIENT_CAP_INTERVAL_USES_WHICH, to
indicate that userspace is aware of this new field.

All drivers that implement the subdev .get_frame_interval() and
.set_frame_interval() operations are updated to return -EINVAL when
operating on the TRY state, preserving the current behaviour.

While at it, fix a bad copy&paste in the documentation of the struct
v4l2_subdev_frame_interval_enum 'which' field.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de> # for imx-media
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com> # for tegra-video
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/media/i2c/ov5648.c b/drivers/media/i2c/ov5648.c
index d0d7e9968f48..4b86d2631bd1 100644
--- a/drivers/media/i2c/ov5648.c
+++ b/drivers/media/i2c/ov5648.c
@@ -2276,6 +2276,13 @@ static int ov5648_get_frame_interval(struct v4l2_subdev *subdev,
 	const struct ov5648_mode *mode;
 	int ret = 0;
 
+	/*
+	 * FIXME: Implement support for V4L2_SUBDEV_FORMAT_TRY, using the V4L2
+	 * subdev active state API.
+	 */
+	if (interval->which != V4L2_SUBDEV_FORMAT_ACTIVE)
+		return -EINVAL;
+
 	mutex_lock(&sensor->mutex);
 
 	mode = sensor->state.mode;