[PATCH 1/4] media: subdev: Add checks for subdev features

Tomi Valkeinen
2024-04-04T10:50:21Z

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.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
drivers/media/v4l2-core/v4l2-subdev.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 4c6198c48dd6..b90b5185e87f 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -1519,6 +1519,33 @@ 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 = sd->ops && sd->ops->video && sd->ops->video->s_stream;
+ has_enable_streams = sd->ops && sd->ops->pad && sd->ops->pad->enable_streams;
+ has_disable_streams = sd->ops && sd->ops->pad && sd->ops->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))

--
2.34.1