[PATCH 03/17] media: v4l2-subdev: Prepare for changes in getting frame descriptors

[Sakari Ailus <sakari.ailus@linux.intel.com>]

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 <sakari.ailus@linux.intel.com>
---
 drivers/media/v4l2-core/v4l2-subdev.c | 59 +++++++++++++++++++++++++++
 include/media/v4l2-subdev.h           | 20 +++++++++
 2 files changed, 79 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index d93ed50255ed..b8acce8f9c33 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 +2672,64 @@ int v4l2_subdev_get_frame_desc_passthrough(struct v4l2_subdev *sd,
 }
 EXPORT_SYMBOL_GPL(v4l2_subdev_get_frame_desc_passthrough);
 
+int v4l2_subdev_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
+			       struct v4l2_mbus_frame_desc *desc)
+{
+	struct v4l2_subdev_format subdev_fmt = {
+		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
+		.pad = pad,
+	};
+	int ret;
+
+	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)
+			return ret;
+
+		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);
+			return -EINVAL;
+		}
+
+		return ret;
+	}
+
+	if (desc->type != V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL &&
+	    desc->type != V4L2_MBUS_FRAME_DESC_TYPE_CSI2)
+		return -EINVAL;
+
+	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)
+		return ret;
+
+	struct v4l2_mbus_frame_desc_entry entry = {
+		.pixelcode = subdev_fmt.format.code,
+	};
+
+	if (desc->type == V4L2_MBUS_FRAME_DESC_TYPE_CSI2) {
+		int dt;
+
+		dt = mipi_csi2_dt_for_mbus(subdev_fmt.format.code);
+		if (dt < 0)
+			return dt;
+
+		entry.bus.csi2.dt = dt;
+	}
+
+	desc->entry[0] = entry;
+	desc->num_entries = 1;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_get_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..c9e74566c85a 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -1778,6 +1778,26 @@ 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
+ * @desc: A pointer to a frame descriptor, with its type field set
+ *
+ * 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.
+ *
+ * Return: %0 on success or negative error code on failure.
+ */
+int v4l2_subdev_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
+			       struct v4l2_mbus_frame_desc *desc);
+
 #endif /* CONFIG_VIDEO_V4L2_SUBDEV_API */
 
 #endif /* CONFIG_MEDIA_CONTROLLER */
-- 
2.47.3