[PATCH v3 03/29] media: v4l2-subdev: Prepare for changes in getting frame descriptors

Introduce v4l2_subdev_alloc_frame_desc() and v4l2_subdev_free_frame_desc()
to both facilitate implementing drivers that need frame descriptors as
well as prepare for having a larger number of frame descriptors.
If the remote sub-device does not support frame descriptors,
v4l2_subdev_get_frame_desc() creates one (with a single entry)
opportunistically, thus avoiding the need to add frame descriptor support
to sensor drivers the device for which only generates a single stream, or
managing the situation on the caller side.

Signed-off-by: Sakari Ailus <[email protected]>
Reviewed-by: Frank Li <[email protected]>
---
 drivers/media/v4l2-core/v4l2-subdev.c | 75 +++++++++++++++++++++++++++
 include/media/v4l2-subdev.h           | 34 ++++++++++++
 2 files changed, 109 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index d93ed50255ed..a5c53dc8c396 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -20,6 +20,7 @@
 #include <linux/version.h>
 #include <linux/videodev2.h>
 
+#include <media/mipi-csi2.h>
 #include <media/v4l2-ctrls.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-event.h>
@@ -2671,6 +2672,80 @@ int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
 }
 EXPORT_SYMBOL_GPL(v4l2_subdev_get_frame_desc_passthrough);
 
+struct v4l2_mbus_frame_desc *
+v4l2_subdev_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
+			   enum v4l2_mbus_frame_desc_type type)
+{
+	int ret;
+
+	if (type != V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL &&
+	    type != V4L2_MBUS_FRAME_DESC_TYPE_CSI2)
+		return ERR_PTR(-EINVAL);
+
+	struct v4l2_mbus_frame_desc *desc = kzalloc_obj(*desc, GFP_KERNEL);
+	if (!desc)
+		return ERR_PTR(-ENOMEM);
+
+	desc->type = type;
+
+	if (v4l2_subdev_has_op(sd, pad, get_frame_desc)) {
+		unsigned int type = desc->type;
+
+		ret = v4l2_subdev_call(sd, pad, get_frame_desc, pad, desc);
+		if (ret < 0)
+			goto err_free;
+
+		if (desc->type != type) {
+			dev_dbg(sd->dev,
+				"wrong type of frame descriptor for pad %d (got %u, expected %u)\n",
+				pad, desc->type, type);
+			ret = -EINVAL;
+			goto err_free;
+		}
+
+		return desc;
+	}
+
+	struct v4l2_subdev_format subdev_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		.pad = pad,
+	};
+	struct v4l2_subdev_state *state =
+		v4l2_subdev_lock_and_get_active_state(sd);
+	ret = v4l2_subdev_call(sd, pad, get_fmt, state, &subdev_fmt);
+	v4l2_subdev_unlock_state(state);
+	if (ret < 0)
+		goto err_free;
+
+	struct v4l2_mbus_frame_desc_entry *entry = &desc->entry[0];
+
+	entry->pixelcode = subdev_fmt.format.code;
+
+	if (desc->type == V4L2_MBUS_FRAME_DESC_TYPE_CSI2) {
+		ret = media_bus_fmt_to_csi2_dt(subdev_fmt.format.code);
+		if (ret < 0)
+			goto err_free;
+
+		entry->bus.csi2.dt = ret;
+	}
+
+	desc->num_entries = 1;
+
+	return desc;
+
+err_free:
+	v4l2_subdev_free_frame_desc(desc);
+
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_get_frame_desc);
+
+void v4l2_subdev_free_frame_desc(struct v4l2_mbus_frame_desc *desc)
+{
+	kfree(desc);
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_free_frame_desc);
+
 #endif /* CONFIG_VIDEO_V4L2_SUBDEV_API */
 
 #endif /* CONFIG_MEDIA_CONTROLLER */
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index d256b7ec8f84..e7127953ac22 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -8,6 +8,7 @@
 #ifndef _V4L2_SUBDEV_H
 #define _V4L2_SUBDEV_H
 
+#include <linux/cleanup.h>
 #include <linux/types.h>
 #include <linux/v4l2-subdev.h>
 #include <media/media-entity.h>
@@ -1778,6 +1779,39 @@ int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
 					   unsigned int pad,
 					   struct v4l2_mbus_frame_desc *fd);
 
+/**
+ * v4l2_subdev_get_frame_desc() - Get a frame descriptor for a pad
+ * @sd: The sub-device
+ * @pad: The number of the pad in @sd from which to obtain the frame descriptor
+ * @type: The type of the frame descriptor
+ *
+ * Obtain a frame descriptor from a sub-device. If the sub-device supports the
+ * get_frame_desc pad operation, its result is returned, just like calling it
+ * directly using v4l2_subdev_call(). If the sub-device driver does not support
+ * it, then a frame descriptor containing a single entry is created using the
+ * information from the sub-device format for types
+ * V4L2_MBUS_FRAME_DESC_TYPE_CSI2 and V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL.
+ *
+ * The caller is required to set @desc->type to the expected bus type.
+ *
+ * The caller is required to release the memory of the frame descriptor entries
+ * for each frame descriptor obtained by calling this function using
+ * v4l2_subdev_free_frame_desc().
+ *
+ * Return: The frame descriptor on success or a negative error code on failure.
+ */
+struct v4l2_mbus_frame_desc *
+v4l2_subdev_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
+			   enum v4l2_mbus_frame_desc_type type);
+
+/**
+ * v4l2_subdev_free_frame_desc() - Release the memory of a frame descriptor
+ * @desc: A pointer to a frame descriptor
+ *
+ * Release the frame descriptor.
+ */
+void v4l2_subdev_free_frame_desc(struct v4l2_mbus_frame_desc *desc);
+
 #endif /* CONFIG_VIDEO_V4L2_SUBDEV_API */
 
 #endif /* CONFIG_MEDIA_CONTROLLER */
-- 
2.47.3