Add new buffer capability flags to indicate if the VIDIOC_PREPARE_BUF or
VIDIOC_CREATE_BUFS ioctls are supported.
The reason for this is that there is currently no way for an application
to detect if VIDIOC_PREPARE_BUF is implemented other than trying it, but
then the buffer is already prepared. You would like to know this before
taking an irreversible action.
Since we need V4L2_BUF_CAP_SUPPORTS_PREPARE_BUF it makes sense to add
V4L2_BUF_CAP_SUPPORTS_CREATE_BUFS as well because not all drivers support
this ioctl.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Acked-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
---
Changes since v1:
- rebased
- improved commit msg
- added missing include for media/v4l2-ioctl.h
---
Documentation/media/uapi/v4l/vidioc-reqbufs.rst | 8 ++++++++
drivers/media/common/videobuf2/videobuf2-v4l2.c | 15 +++++++++++++--
include/uapi/linux/videodev2.h | 12 +++++++-----
3 files changed, 28 insertions(+), 7 deletions(-)
diff --git a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
index e62a15782790..092d6373380a 100644
--- a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
+++ b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
@@ -118,6 +118,8 @@ aborting or finishing any DMA in progress, an implicit
.. _V4L2-BUF-CAP-SUPPORTS-DMABUF:
.. _V4L2-BUF-CAP-SUPPORTS-REQUESTS:
.. _V4L2-BUF-CAP-SUPPORTS-ORPHANED-BUFS:
+.. _V4L2-BUF-CAP-SUPPORTS-PREPARE-BUF:
+.. _V4L2-BUF-CAP-SUPPORTS-CREATE-BUFS:
.. cssclass:: longtable
@@ -143,6 +145,12 @@ aborting or finishing any DMA in progress, an implicit
- The kernel allows calling :ref:`VIDIOC_REQBUFS` while buffers are still
mapped or exported via DMABUF. These orphaned buffers will be freed
when they are unmapped or when the exported DMABUF fds are closed.
+ * - ``V4L2_BUF_CAP_SUPPORTS_PREPARE_BUF``
+ - 0x00000020
+ - This buffer type supports :ref:`VIDIOC_PREPARE_BUF`.
+ * - ``V4L2_BUF_CAP_SUPPORTS_CREATE_BUFS``
+ - 0x00000040
+ - This buffer type supports :ref:`VIDIOC_CREATE_BUFS`.
Return Value
============
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 1244c246d0c4..5273f574fb7a 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -28,6 +28,7 @@
#include <media/v4l2-device.h>
#include <media/v4l2-fh.h>
#include <media/v4l2-event.h>
+#include <media/v4l2-ioctl.h>
#include <media/v4l2-common.h>
#include <media/videobuf2-v4l2.h>
@@ -870,6 +871,16 @@ static inline bool vb2_queue_is_busy(struct video_device *vdev, struct file *fil
return vdev->queue->owner && vdev->queue->owner != file->private_data;
}
+static void fill_buf_caps_vdev(struct video_device *vdev, u32 *caps)
+{
+ *caps = 0;
+ fill_buf_caps(vdev->queue, caps);
+ if (vdev->ioctl_ops->vidioc_prepare_buf)
+ *caps |= V4L2_BUF_CAP_SUPPORTS_PREPARE_BUF;
+ if (vdev->ioctl_ops->vidioc_create_bufs)
+ *caps |= V4L2_BUF_CAP_SUPPORTS_CREATE_BUFS;
+}
+
/* vb2 ioctl helpers */
int vb2_ioctl_reqbufs(struct file *file, void *priv,
@@ -878,7 +889,7 @@ int vb2_ioctl_reqbufs(struct file *file, void *priv,
struct video_device *vdev = video_devdata(file);
int res = vb2_verify_memory_type(vdev->queue, p->memory, p->type);
- fill_buf_caps(vdev->queue, &p->capabilities);
+ fill_buf_caps_vdev(vdev, &p->capabilities);
if (res)
return res;
if (vb2_queue_is_busy(vdev, file))
@@ -900,7 +911,7 @@ int vb2_ioctl_create_bufs(struct file *file, void *priv,
p->format.type);
p->index = vdev->queue->num_buffers;
- fill_buf_caps(vdev->queue, &p->capabilities);
+ fill_buf_caps_vdev(vdev, &p->capabilities);
/*
* If count == 0, then just check if memory and type are valid.
* Any -EBUSY result from vb2_verify_memory_type can be mapped to 0.
diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 2a223835214c..8ebc66e311e0 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -875,11 +875,13 @@ struct v4l2_requestbuffers {
};
/* capabilities for struct v4l2_requestbuffers and v4l2_create_buffers */
-#define V4L2_BUF_CAP_SUPPORTS_MMAP (1 << 0)
-#define V4L2_BUF_CAP_SUPPORTS_USERPTR (1 << 1)
-#define V4L2_BUF_CAP_SUPPORTS_DMABUF (1 << 2)
-#define V4L2_BUF_CAP_SUPPORTS_REQUESTS (1 << 3)
-#define V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS (1 << 4)
+#define V4L2_BUF_CAP_SUPPORTS_MMAP (1 << 0)
+#define V4L2_BUF_CAP_SUPPORTS_USERPTR (1 << 1)
+#define V4L2_BUF_CAP_SUPPORTS_DMABUF (1 << 2)
+#define V4L2_BUF_CAP_SUPPORTS_REQUESTS (1 << 3)
+#define V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS (1 << 4)
+#define V4L2_BUF_CAP_SUPPORTS_PREPARE_BUF (1 << 5)
+#define V4L2_BUF_CAP_SUPPORTS_CREATE_BUFS (1 << 6)
/**
* struct v4l2_plane - plane info for multi-planar buffers
--
2.19.1
