v4l: subdev: Add pad config allocator and init

Add a new subdev operation to initialize a subdev pad config array, and a helper function to allocate and initialize the array. This can be used by bridge drivers to implement try format based on subdev pad operations.

Signed-off-by Laurent Pinchart <[email protected]>

Acked-by Vaibhav Hiremath <[email protected]>

---
 drivers/media/v4l2-core/v4l2-subdev.c | 19 ++++++++++++++++++-
 include/media/v4l2-subdev.h           |  3 +++
 2 files changed, 21 insertions(+), 1 deletion(-)

drivers/media/v4l2-core/v4l2-subdev.c +18 -1

index 63596063b213..d594fe566be2 100644
@@ -35,7 +35,7 @@
 static int subdev_fh_init(struct v4l2_subdev_fh *fh, struct v4l2_subdev *sd)
 {
 #if defined(CONFIG_VIDEO_V4L2_SUBDEV_API)
-	fh->pad = kzalloc(sizeof(*fh->pad) * sd->entity.num_pads, GFP_KERNEL);
+	fh->pad = v4l2_subdev_alloc_pad_config(sd);
 	if (fh->pad == NULL)
 		return -ENOMEM;
 #endif

@@ -569,6 +569,23 @@ int v4l2_subdev_link_validate(struct media_link *link)
 		sink, link, &source_fmt, &sink_fmt);
 }
 EXPORT_SYMBOL_GPL(v4l2_subdev_link_validate);
+
+struct v4l2_subdev_pad_config *v4l2_subdev_alloc_pad_config(struct v4l2_subdev *sd)
+{
+	struct v4l2_subdev_pad_config *cfg;
+
+	if (!sd->entity.num_pads)
+		return NULL;
+
+	cfg = kcalloc(sd->entity.num_pads, sizeof(*cfg), GFP_KERNEL);
+	if (!cfg)
+		return NULL;
+
+	v4l2_subdev_call(sd, pad, init_cfg, cfg);
+
+	return cfg;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_alloc_pad_config);
 #endif /* CONFIG_MEDIA_CONTROLLER */
 
 void v4l2_subdev_init(struct v4l2_subdev *sd, const struct v4l2_subdev_ops *ops)

include/media/v4l2-subdev.h +2 -0

index 8f5da73dacff..7860d67574f5 100644
@@ -483,6 +483,8 @@ struct v4l2_subdev_pad_config {
  *                  may be adjusted by the subdev driver to device capabilities.
  */
 struct v4l2_subdev_pad_ops {
+	void (*init_cfg)(struct v4l2_subdev *sd,
+			 struct v4l2_subdev_pad_config *cfg);
 	int (*enum_mbus_code)(struct v4l2_subdev *sd,
 			      struct v4l2_subdev_pad_config *cfg,
 			      struct v4l2_subdev_mbus_code_enum *code);

include/media/v4l2-subdev.h +0 -0

 #endif /* CONFIG_MEDIA_CONTROLLER */
 void v4l2_subdev_init(struct v4l2_subdev *sd,
 		      const struct v4l2_subdev_ops *ops);

Hi Laurent,

Looks good, but I have one question. See below.

Quoted 12 lines · Laurent Pinchart

Add a new subdev operation to initialize a subdev pad config array, and a helper function to allocate and initialize the array. This can be used by bridge drivers to implement try format based on subdev pad operations.

Signed-off-by Laurent Pinchart <[email protected]>

Acked-by Vaibhav Hiremath <[email protected]>

---

 drivers/media/v4l2-core/v4l2-subdev.c | 19 ++++++++++++++++++-
 include/media/v4l2-subdev.h           |  3 +++
 2 files changed, 21 insertions(+), 1 deletion(-)

Quoted 18 lines

include/media/v4l2-subdev.h +2 -0

index 8f5da73dacff..7860d67574f5 100644
@@ -483,6 +483,8 @@ struct v4l2_subdev_pad_config {
  *                  may be adjusted by the subdev driver to device
  capabilities. */
 
 struct v4l2_subdev_pad_ops {
+	void (*init_cfg)(struct v4l2_subdev *sd,
+			 struct v4l2_subdev_pad_config *cfg);
 	int (*enum_mbus_code)(struct v4l2_subdev *sd,
 			      struct v4l2_subdev_pad_config *cfg,

include/media/v4l2-subdev.h +0 -0

 			      struct v4l2_subdev_mbus_code_enum *code);

@@ -675,6 +677,7 @@ int v4l2_subdev_link_validate_default(struct
 v4l2_subdev *sd,
 				      struct v4l2_subdev_format *source_fmt,
 				      struct v4l2_subdev_format *sink_fmt);

include/media/v4l2-subdev.h int v4l2_subdev_link_validate_default(struct · line 682

Quoted 3 lines

include/media/v4l2-subdev.h +1 -0

 int v4l2_subdev_link_validate(struct media_link *link);
+struct v4l2_subdev_pad_config *v4l2_subdev_alloc_pad_config(struct
 v4l2_subdev *sd);

Would it make sense to add a simple static inline v4l2_subdev_free_pad_config here? All it does is a kfree, but still it makes it symmetrical and if we ever need to do more than a kfree, then we are able to do so.

At the very least this header needs a comment if we don't add a free_pad_config that the caller needs to kfree the pointer.

Quoted 3 lines

include/media/v4l2-subdev.h +0 -0

 #endif /* CONFIG_MEDIA_CONTROLLER */

void v4l2_subdev_init(struct v4l2_subdev *sd,
const struct v4l2_subdev_ops *ops);