From 009905ec50433259c05f474251000b040098564e Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Mon, 18 Sep 2023 15:48:38 +0300 Subject: media: v4l2-subdev: Document and enforce .s_stream() requirements The subdev .s_stream() operation must not be called to start an already started subdev, or stop an already stopped one. This requirement has never been formally documented. Fix it, and catch possible offenders with a WARN_ON() in the call_s_stream() wrapper. Signed-off-by: Laurent Pinchart Signed-off-by: Sakari Ailus Signed-off-by: Hans Verkuil --- include/media/v4l2-subdev.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/media') diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h index 820e38ec3dc9..5f59ff0796b7 100644 --- a/include/media/v4l2-subdev.h +++ b/include/media/v4l2-subdev.h @@ -446,7 +446,9 @@ enum v4l2_subdev_pre_streamon_flags { * @s_stream: start (enabled == 1) or stop (enabled == 0) streaming on the * sub-device. Failure on stop will remove any resources acquired in * streaming start, while the error code is still returned by the driver. - * Also see call_s_stream wrapper in v4l2-subdev.c. + * The caller shall track the subdev state, and shall not start or stop an + * already started or stopped subdev. Also see call_s_stream wrapper in + * v4l2-subdev.c. * * @g_pixelaspect: callback to return the pixelaspect ratio. * -- cgit