media: videodev2.h: add new capabilities for buffer types

VIDIOC_REQBUFS and VIDIOC_CREATE_BUFFERS will return capabilities
telling userspace what the given buffer type is capable of.

Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

diff --git a/Documentation/media/uapi/v4l/vidioc-create-bufs.rst b/Documentation/media/uapi/v4l/vidioc-create-bufs.rst
index a39e18d..eadf6f7 100644 (file)
--- a/Documentation/media/uapi/v4l/vidioc-create-bufs.rst
+++ b/Documentation/media/uapi/v4l/vidioc-create-bufs.rst
@@ -102,7 +102,19 @@ than the number requested.
       - ``format``
       - Filled in by the application, preserved by the driver.
     * - __u32
-      - ``reserved``\ [8]
+      - ``capabilities``
+      - Set by the driver. If 0, then the driver doesn't support
+        capabilities. In that case all you know is that the driver is
+       guaranteed to support ``V4L2_MEMORY_MMAP`` and *might* support
+       other :c:type:`v4l2_memory` types. It will not support any others
+       capabilities. See :ref:`here <v4l2-buf-capabilities>` for a list of the
+       capabilities.
+
+       If you want to just query the capabilities without making any
+       other changes, then set ``count`` to 0, ``memory`` to
+       ``V4L2_MEMORY_MMAP`` and ``format.type`` to the buffer type.
+    * - __u32
+      - ``reserved``\ [7]
       - A place holder for future extensions. Drivers and applications
        must set the array to zero.
 

diff --git a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
index 316f52c..d4bbbb0 100644 (file)
--- a/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
+++ b/Documentation/media/uapi/v4l/vidioc-reqbufs.rst
@@ -88,10 +88,50 @@ any DMA in progress, an implicit
        ``V4L2_MEMORY_DMABUF`` or ``V4L2_MEMORY_USERPTR``. See
        :c:type:`v4l2_memory`.
     * - __u32
-      - ``reserved``\ [2]
+      - ``capabilities``
+      - Set by the driver. If 0, then the driver doesn't support
+        capabilities. In that case all you know is that the driver is
+       guaranteed to support ``V4L2_MEMORY_MMAP`` and *might* support
+       other :c:type:`v4l2_memory` types. It will not support any others
+       capabilities.
+
+       If you want to query the capabilities with a minimum of side-effects,
+       then this can be called with ``count`` set to 0, ``memory`` set to
+       ``V4L2_MEMORY_MMAP`` and ``type`` set to the buffer type. This will
+       free any previously allocated buffers, so this is typically something
+       that will be done at the start of the application.
+    * - __u32
+      - ``reserved``\ [1]
       - A place holder for future extensions. Drivers and applications
        must set the array to zero.
 
+.. tabularcolumns:: |p{6.1cm}|p{2.2cm}|p{8.7cm}|
+
+.. _v4l2-buf-capabilities:
+.. _V4L2-BUF-CAP-SUPPORTS-MMAP:
+.. _V4L2-BUF-CAP-SUPPORTS-USERPTR:
+.. _V4L2-BUF-CAP-SUPPORTS-DMABUF:
+.. _V4L2-BUF-CAP-SUPPORTS-REQUESTS:
+
+.. cssclass:: longtable
+
+.. flat-table:: V4L2 Buffer Capabilities Flags
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       3 1 4
+
+    * - ``V4L2_BUF_CAP_SUPPORTS_MMAP``
+      - 0x00000001
+      - This buffer type supports the ``V4L2_MEMORY_MMAP`` streaming mode.
+    * - ``V4L2_BUF_CAP_SUPPORTS_USERPTR``
+      - 0x00000002
+      - This buffer type supports the ``V4L2_MEMORY_USERPTR`` streaming mode.
+    * - ``V4L2_BUF_CAP_SUPPORTS_DMABUF``
+      - 0x00000004
+      - This buffer type supports the ``V4L2_MEMORY_DMABUF`` streaming mode.
+    * - ``V4L2_BUF_CAP_SUPPORTS_REQUESTS``
+      - 0x00000008
+      - This buffer type supports :ref:`requests <media-request-api>`.
 
 Return Value
 ============

diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 2350151..55d45a3 100644 (file)
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -856,9 +856,16 @@ struct v4l2_requestbuffers {
        __u32                   count;
        __u32                   type;           /* enum v4l2_buf_type */
        __u32                   memory;         /* enum v4l2_memory */
-       __u32                   reserved[2];
+       __u32                   capabilities;
+       __u32                   reserved[1];
 };
 
+/* 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)
+
 /**
  * struct v4l2_plane - plane info for multi-planar buffers
  * @bytesused:         number of bytes occupied by data in the plane (payload)
@@ -2319,6 +2326,7 @@ struct v4l2_dbg_chip_info {
  *             return: number of created buffers
  * @memory:    enum v4l2_memory; buffer memory type
  * @format:    frame format, for which buffers are requested
+ * @capabilities: capabilities of this buffer type.
  * @reserved:  future extensions
  */
 struct v4l2_create_buffers {
@@ -2326,7 +2334,8 @@ struct v4l2_create_buffers {
        __u32                   count;
        __u32                   memory;
        struct v4l2_format      format;
-       __u32                   reserved[8];
+       __u32                   capabilities;
+       __u32                   reserved[7];
 };
 
 /*