media: subdev: Add checks for subdev features

Add some checks to verify that the subdev driver implements required
features.

A subdevice that supports streams (V4L2_SUBDEV_FL_STREAMS) must do one
of the following:

- Implement neither .enable/disable_streams() nor .s_stream(), if the
  subdev is part of a video driver that uses an internal method to
  enable the subdev.
- Implement only .enable/disable_streams(), if support for legacy
  sink-side subdevices is not needed.
- Implement .enable/disable_streams() and .s_stream(), if support for
  legacy sink-side subdevices is needed.

At the moment the framework doesn't check this requirement. Add the
check.

Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Umang Jain <umang.jain@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 56df3906eee69fefc0083a11b5d21ee4cd349561..09b4122d9ab7c22175c3ba0033e3b2d5f6761596 100644 (file)
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -1588,6 +1588,33 @@ int __v4l2_subdev_init_finalize(struct v4l2_subdev *sd, const char *name,
                                struct lock_class_key *key)
 {
        struct v4l2_subdev_state *state;
+       struct device *dev = sd->dev;
+       bool has_disable_streams;
+       bool has_enable_streams;
+       bool has_s_stream;
+
+       /* Check that the subdevice implements the required features */
+
+       has_s_stream = v4l2_subdev_has_op(sd, video, s_stream);
+       has_enable_streams = v4l2_subdev_has_op(sd, pad, enable_streams);
+       has_disable_streams = v4l2_subdev_has_op(sd, pad, disable_streams);
+
+       if (has_enable_streams != has_disable_streams) {
+               dev_err(dev,
+                       "subdev '%s' must implement both or neither of .enable_streams() and .disable_streams()\n",
+                       sd->name);
+               return -EINVAL;
+       }
+
+       if (sd->flags & V4L2_SUBDEV_FL_STREAMS) {
+               if (has_s_stream && !has_enable_streams) {
+                       dev_err(dev,
+                               "subdev '%s' must implement .enable/disable_streams()\n",
+                               sd->name);
+
+                       return -EINVAL;
+               }
+       }
 
        state = __v4l2_subdev_state_alloc(sd, name, key);
        if (IS_ERR(state))