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

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On 04/04/2024 14:09, Sakari Ailus wrote:
Moi,

On Thu, Apr 04, 2024 at 01:50:00PM +0300, Tomi Valkeinen wrote:
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@xxxxxxxxxxxxxxxx>
---
  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;

There is v4l2_subdev_has_op(). Please also run:

	./scripts/checkpatch.pl --strict --max-line-length=80

on this.

+
+	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) {

Is the s_stream callback allowed to be something else than NULL or
v4l2_subdev_s_stream_helper?

v4l2_subdev_s_stream_helper() only supports subdevs with a single source pad. The driver can implement its own version.

 Tomi





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