Reference counting to subdev file handles and media bus code enumeration

index 46562de..7600714 100644
@@ -382,7 +382,6 @@ static int media_enum_entities(struct media_device *media)
 
 		entity = &media->entities[media->entities_count];
 		memset(entity, 0, sizeof(*entity));
-		entity->fd = -1;
 		entity->info.id = id | MEDIA_ENT_ID_FLAG_NEXT;
 		entity->media = media;
 

index 2296fe2..79934a7 100644
@@ -49,6 +49,7 @@ struct media_entity {
 
 	char devname[32];
 	int fd;
+	unsigned int open_count;
 	__u32 padding[6];
 };
 

174 lines not on this page · raw message

index 5d55482..43d5c1f 100644
@@ -30,19 +30,21 @@ struct media_entity;
  * @brief Open a sub-device.
  * @param entity - sub-device media entity.
  *
- * Open the V4L2 subdev device node associated with @a entity. The file
- * descriptor is stored in the media_entity structure.
+ * Open the V4L2 subdev device node associated with @a entity. The
+ * file descriptor is stored in the media_entity structure. The subdev
+ * will stay open until the last user has closed it using
+ * v4l2_subdev_close(), i.e. the calls are reference-counted.
  *
  * @return 0 on success, or a negative error code on failure.
  */
 int v4l2_subdev_open(struct media_entity *entity);
 
 /**
- * @brief Close a sub-device.
+ * @brief Release a sub-device.
  * @param entity - sub-device media entity.
  *
- * Close the V4L2 subdev device node associated with the @a entity and opened by
- * a previous call to v4l2_subdev_open() (either explicit or implicit).
+ * Releases a reference to a sub-device. The device will stay open
+ * until the last remaining user has released the device.
  */
 void v4l2_subdev_close(struct media_entity *entity);
 

index 56964ce..946c030 100644
@@ -27,6 +27,7 @@
 #include <fcntl.h>
 #include <stdbool.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 

@@ -64,6 +65,51 @@ void v4l2_subdev_close(struct media_entity *entity)
 	}
 }
 
+struct v4l2_subdev_mbus_codes *
+v4l2_subdev_enum_mbus_code(struct media_entity *entity, unsigned int pad)
+{
+	struct v4l2_subdev_mbus_code_enum c;
+	struct v4l2_subdev_mbus_codes *codes = NULL;
+	int ret;
+
+	ret = v4l2_subdev_open(entity);
+	if (ret < 0)
+		return NULL;
+
+	memset(&c, 0, sizeof(c));
+	c.pad = pad;
+
+	for (; ; c.index++) {
+		void *tmp;
+
+		ret = ioctl(entity->fd, VIDIOC_SUBDEV_ENUM_MBUS_CODE, &c);
+		if (ret == -1) {
+			if (errno == EINVAL)
+				break;
+			else
+				goto out_err;
+		}
+
+		tmp = realloc(codes, sizeof(*codes)
+			      + (c.index + 1) * sizeof(codes->code[0]));
+		if (!tmp)
+			goto out_err;
+		codes = tmp;
+
+		codes->code[c.index] = c.code;
+	}
+
+	codes->ncode = c.index;
+
+	v4l2_subdev_close(entity);
+	return codes;
+
+out_err:
+	v4l2_subdev_close(entity);
+	free(codes);
+	return NULL;
+}
+
 int v4l2_subdev_get_format(struct media_entity *entity,
 	struct v4l2_mbus_framefmt *format, unsigned int pad,
 	enum v4l2_subdev_format_whence which)

index 43d5c1f..8b42f4d 100644
@@ -48,6 +48,26 @@ int v4l2_subdev_open(struct media_entity *entity);
  */
 void v4l2_subdev_close(struct media_entity *entity);
 
+struct v4l2_subdev_mbus_codes {
+	unsigned int ncode;
+	unsigned int code[0];
+} __packed;
+
+/**
+ * @brief Enumerate mbus pixel codes.
+ * @param entity - subdev-device media entity.
+ * @param pad - the pad of the media entity
+ *
+ * Enumerate media bus pixel codes. This is just a wrapper for
+ * VIDIOC_SUBDEV_ENUM_MBUS_CODE IOCTL.
+ *
+ * @return NULL on error; otherwise struct v4l2_subdev_mbus_code_enum
+ * containing the media bus codes. The user MUST use free(3) to
+ * release the returned struct once the user no longer needs it.
+ */
+struct v4l2_subdev_mbus_codes *
+v4l2_subdev_enum_mbus_code(struct media_entity *entity, unsigned int pad);
+
 /**
  * @brief Retrieve the format on a pad.
  * @param entity - subdev-device media entity.

index 946c030..d553216 100644
@@ -65,6 +65,19 @@ void v4l2_subdev_close(struct media_entity *entity)
 	}
 }
 
+static int mbus_code_sort(const void *p1, const void *p2)
+{
+	const unsigned int *c1 = p1, *c2 = p2;
+
+	if (*c1 < *c2)
+		return -1;
+
+	if (*c1 > *c2)
+		return 1;
+
+	return 0;
+}
+
 struct v4l2_subdev_mbus_codes *
 v4l2_subdev_enum_mbus_code(struct media_entity *entity, unsigned int pad)
 {

@@ -100,6 +113,7 @@ v4l2_subdev_enum_mbus_code(struct media_entity *entity, unsigned int pad)
 	}
 
 	codes->ncode = c.index;
+	qsort(codes->code, codes->ncode, sizeof(*codes->code), &mbus_code_sort);
 
 	v4l2_subdev_close(entity);
 	return codes;