dmabuf: implement linux_dmabuf extension
authorPekka Paalanen <pekka.paalanen@collabora.co.uk>
Mon, 29 Sep 2014 18:18:40 +0000 (14:18 -0400)
committerPekka Paalanen <pekka.paalanen@collabora.co.uk>
Fri, 14 Aug 2015 12:53:25 +0000 (15:53 +0300)
v2 changes:
- implement the revised protocol
- add basic sanity checks when creating buffer and check for support
- add way to attach user data to the dmabuf for renderer use
- bump max number of planes to 4 to follow DRM AddFb2 ioctl
- improve errors handling
- use separate linux_dmabuf_buffer fields for the different wl_resource
  types
- as SERVER_ERROR code is no more, use a wl_display "generic" error for
  emergency-disconneting a client we fail to process
- more documentation
- change y-invert from per-plane boolean to per-buffer flag

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Makefile.am
src/compositor.c
src/compositor.h
src/linux-dmabuf.c [new file with mode: 0644]
src/linux-dmabuf.h [new file with mode: 0644]

index 7acbc2de2e08eb98cd9a13835c2189fc4220f2a5..9c1cf25851fccad38d944f4cca5902ed386afdc7 100644 (file)
@@ -87,6 +87,8 @@ weston_SOURCES =                                      \
        src/timeline.h                                  \
        src/timeline-object.h                           \
        src/main.c                                      \
+       src/linux-dmabuf.c                              \
+       src/linux-dmabuf.h                              \
        shared/helpers.h                                \
        shared/matrix.c                                 \
        shared/matrix.h                                 \
index 0268afcaece997add2c119230e64a333de190448..cbef4dc82cda2c9c76ff76dcb3b94edc2033ce45 100644 (file)
@@ -4672,6 +4672,34 @@ weston_compositor_read_presentation_clock(
        }
 }
 
+/** Import dmabuf buffer into current renderer
+ *
+ * \param compositor
+ * \param buffer the dmabuf buffer to import
+ * \return true on usable buffers, false otherwise
+ *
+ * This function tests that the linux_dmabuf_buffer is usable
+ * for the current renderer. Returns false on unusable buffers. Usually
+ * usability is tested by importing the dmabufs for composition.
+ *
+ * This hook is also used for detecting if the renderer supports
+ * dmabufs at all. If the renderer hook is NULL, dmabufs are not
+ * supported.
+ * */
+WL_EXPORT bool
+weston_compositor_import_dmabuf(struct weston_compositor *compositor,
+                               struct linux_dmabuf_buffer *buffer)
+{
+       struct weston_renderer *renderer;
+
+       renderer = compositor->renderer;
+
+       if (renderer->import_dmabuf == NULL)
+               return false;
+
+       return renderer->import_dmabuf(compositor, buffer);
+}
+
 WL_EXPORT void
 weston_version(int *major, int *minor, int *micro)
 {
index d1ca9ab7e7f3d8b26e576c88ec6f4d638048f255..c4c81f099b240106f4483adc8ccef1e606e12975 100644 (file)
@@ -57,6 +57,7 @@ struct weston_seat;
 struct weston_output;
 struct input_method;
 struct weston_pointer;
+struct linux_dmabuf_buffer;
 
 enum weston_keyboard_modifier {
        MODIFIER_CTRL = (1 << 0),
@@ -588,6 +589,10 @@ struct weston_renderer {
                                    void *target, size_t size,
                                    int src_x, int src_y,
                                    int width, int height);
+
+       /** See weston_compositor_import_dmabuf() */
+       bool (*import_dmabuf)(struct weston_compositor *ec,
+                             struct linux_dmabuf_buffer *buffer);
 };
 
 enum weston_capability {
@@ -1364,6 +1369,10 @@ weston_compositor_read_presentation_clock(
                        const struct weston_compositor *compositor,
                        struct timespec *ts);
 
+bool
+weston_compositor_import_dmabuf(struct weston_compositor *compositor,
+                               struct linux_dmabuf_buffer *buffer);
+
 void
 weston_compositor_shutdown(struct weston_compositor *ec);
 void
diff --git a/src/linux-dmabuf.c b/src/linux-dmabuf.c
new file mode 100644 (file)
index 0000000..90c9757
--- /dev/null
@@ -0,0 +1,497 @@
+/*
+ * Copyright © 2014, 2015 Collabora, Ltd.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of the copyright holders not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission.  The copyright holders make
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+ * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "config.h"
+
+#include <assert.h>
+#include <unistd.h>
+#include <sys/types.h>
+
+#include "compositor.h"
+#include "linux-dmabuf.h"
+#include "linux-dmabuf-server-protocol.h"
+
+static void
+linux_dmabuf_buffer_destroy(struct linux_dmabuf_buffer *buffer)
+{
+       int i;
+
+       for (i = 0; i < buffer->n_planes; i++) {
+               close(buffer->dmabuf_fd[i]);
+               buffer->dmabuf_fd[i] = -1;
+       }
+
+       buffer->n_planes = 0;
+       free(buffer);
+}
+
+static void
+destroy_params(struct wl_resource *params_resource)
+{
+       struct linux_dmabuf_buffer *buffer;
+
+       buffer = wl_resource_get_user_data(params_resource);
+
+       if (!buffer)
+               return;
+
+       linux_dmabuf_buffer_destroy(buffer);
+}
+
+static void
+params_destroy(struct wl_client *client, struct wl_resource *resource)
+{
+       wl_resource_destroy(resource);
+}
+
+static void
+params_add(struct wl_client *client,
+          struct wl_resource *params_resource,
+          int32_t name_fd,
+          uint32_t plane_idx,
+          uint32_t offset,
+          uint32_t stride,
+          uint32_t modifier_hi,
+          uint32_t modifier_lo)
+{
+       struct linux_dmabuf_buffer *buffer;
+
+       buffer = wl_resource_get_user_data(params_resource);
+       if (!buffer) {
+               wl_resource_post_error(params_resource,
+                       ZLINUX_BUFFER_PARAMS_ERROR_ALREADY_USED,
+                       "params was already used to create a wl_buffer");
+               close(name_fd);
+               return;
+       }
+
+       assert(buffer->params_resource == params_resource);
+       assert(!buffer->buffer_resource);
+
+       if (plane_idx >= MAX_DMABUF_PLANES) {
+               wl_resource_post_error(params_resource,
+                       ZLINUX_BUFFER_PARAMS_ERROR_PLANE_IDX,
+                       "plane index %u is too high", plane_idx);
+               close(name_fd);
+               return;
+       }
+
+       if (buffer->dmabuf_fd[plane_idx] != -1) {
+               wl_resource_post_error(params_resource,
+                       ZLINUX_BUFFER_PARAMS_ERROR_PLANE_SET,
+                       "a dmabuf has already been added for plane %u",
+                       plane_idx);
+               close(name_fd);
+               return;
+       }
+
+       buffer->dmabuf_fd[plane_idx] = name_fd;
+       buffer->offset[plane_idx] = offset;
+       buffer->stride[plane_idx] = stride;
+       buffer->modifier[plane_idx] = ((uint64_t)modifier_hi << 32) |
+                                     modifier_lo;
+       buffer->n_planes++;
+}
+
+static void
+linux_dmabuf_wl_buffer_destroy(struct wl_client *client,
+                              struct wl_resource *resource)
+{
+       wl_resource_destroy(resource);
+}
+
+static const struct wl_buffer_interface linux_dmabuf_buffer_implementation = {
+       linux_dmabuf_wl_buffer_destroy
+};
+
+static void
+destroy_linux_dmabuf_wl_buffer(struct wl_resource *resource)
+{
+       struct linux_dmabuf_buffer *buffer;
+
+       buffer = wl_resource_get_user_data(resource);
+       assert(buffer->buffer_resource == resource);
+       assert(!buffer->params_resource);
+
+       if (buffer->user_data_destroy_func)
+               buffer->user_data_destroy_func(buffer);
+
+       linux_dmabuf_buffer_destroy(buffer);
+}
+
+static void
+params_create(struct wl_client *client,
+             struct wl_resource *params_resource,
+             int32_t width,
+             int32_t height,
+             uint32_t format,
+             uint32_t flags)
+{
+       struct linux_dmabuf_buffer *buffer;
+       int i;
+
+       buffer = wl_resource_get_user_data(params_resource);
+
+       if (!buffer) {
+               wl_resource_post_error(params_resource,
+                       ZLINUX_BUFFER_PARAMS_ERROR_ALREADY_USED,
+                       "params was already used to create a wl_buffer");
+               return;
+       }
+
+       assert(buffer->params_resource == params_resource);
+       assert(!buffer->buffer_resource);
+
+       /* Switch the linux_dmabuf_buffer object from params resource to
+        * eventually wl_buffer resource.
+        */
+       wl_resource_set_user_data(buffer->params_resource, NULL);
+       buffer->params_resource = NULL;
+
+       if (!buffer->n_planes) {
+               wl_resource_post_error(params_resource,
+                       ZLINUX_BUFFER_PARAMS_ERROR_INCOMPLETE,
+                       "no dmabuf has been added to the params");
+               goto err_out;
+       }
+
+       /* Check for holes in the dmabufs set (e.g. [0, 1, 3]) */
+       for (i = 0; i < buffer->n_planes; i++) {
+               if (buffer->dmabuf_fd[i] == -1) {
+                       wl_resource_post_error(params_resource,
+                               ZLINUX_BUFFER_PARAMS_ERROR_INCOMPLETE,
+                               "no dmabuf has been added for plane %i", i);
+                       goto err_out;
+               }
+       }
+
+       buffer->width = width;
+       buffer->height = height;
+       buffer->format = format;
+       buffer->flags = flags;
+
+       if (width < 1 || height < 1) {
+               wl_resource_post_error(params_resource,
+                       ZLINUX_BUFFER_PARAMS_ERROR_INVALID_DIMENSIONS,
+                       "invalid width %d or height %d", width, height);
+               goto err_out;
+       }
+
+       for (i = 0; i < buffer->n_planes; i++) {
+               off_t size;
+
+               if ((uint64_t) buffer->offset[i] + buffer->stride[i] > UINT32_MAX) {
+                       wl_resource_post_error(params_resource,
+                               ZLINUX_BUFFER_PARAMS_ERROR_OUT_OF_BOUNDS,
+                               "size overflow for plane %i", i);
+                       goto err_out;
+               }
+
+               if (i == 0 &&
+                  (uint64_t) buffer->offset[i] +
+                  (uint64_t) buffer->stride[i] * height > UINT32_MAX) {
+                       wl_resource_post_error(params_resource,
+                               ZLINUX_BUFFER_PARAMS_ERROR_OUT_OF_BOUNDS,
+                               "size overflow for plane %i", i);
+                       goto err_out;
+               }
+
+               /* Don't report an error as it might be caused
+                * by the kernel not supporting seeking on dmabuf */
+               size = lseek(buffer->dmabuf_fd[i], 0, SEEK_END);
+               if (size == -1)
+                       break;
+
+               if (buffer->offset[i] >= size) {
+                       wl_resource_post_error(params_resource,
+                               ZLINUX_BUFFER_PARAMS_ERROR_OUT_OF_BOUNDS,
+                               "invalid offset %i for plane %i",
+                               buffer->offset[i], i);
+                       goto err_out;
+               }
+
+               if (buffer->offset[i] + buffer->stride[i] > size) {
+                       wl_resource_post_error(params_resource,
+                               ZLINUX_BUFFER_PARAMS_ERROR_OUT_OF_BOUNDS,
+                               "invalid stride %i for plane %i",
+                               buffer->stride[i], i);
+                       goto err_out;
+               }
+
+               /* Only valid for first plane as other planes might be
+                * sub-sampled according to fourcc format */
+               if (i == 0 &&
+                   buffer->offset[i] + buffer->stride[i] * height > size) {
+                       wl_resource_post_error(params_resource,
+                               ZLINUX_BUFFER_PARAMS_ERROR_OUT_OF_BOUNDS,
+                               "invalid buffer stride or height for plane %i", i);
+                       goto err_out;
+               }
+       }
+
+       /* XXX: Some additional sanity checks could be done with respect
+        * to the fourcc format. A centralized collection (kernel or
+        * libdrm) would be useful to avoid code duplication for these
+        * checks (e.g. drm_format_num_planes).
+        */
+
+       if (!weston_compositor_import_dmabuf(buffer->compositor, buffer))
+               goto err_failed;
+
+       buffer->buffer_resource = wl_resource_create(client,
+                                                    &wl_buffer_interface,
+                                                    1, 0);
+       if (!buffer->buffer_resource) {
+               wl_resource_post_no_memory(params_resource);
+               goto err_buffer;
+       }
+
+       wl_resource_set_implementation(buffer->buffer_resource,
+                                      &linux_dmabuf_buffer_implementation,
+                                      buffer, destroy_linux_dmabuf_wl_buffer);
+
+       zlinux_buffer_params_send_created(params_resource,
+                                         buffer->buffer_resource);
+
+       return;
+
+err_buffer:
+       if (buffer->user_data_destroy_func)
+               buffer->user_data_destroy_func(buffer);
+
+err_failed:
+       zlinux_buffer_params_send_failed(params_resource);
+
+err_out:
+       linux_dmabuf_buffer_destroy(buffer);
+}
+
+static const struct zlinux_buffer_params_interface
+zlinux_buffer_params_implementation = {
+       params_destroy,
+       params_add,
+       params_create
+};
+
+static void
+linux_dmabuf_destroy(struct wl_client *client, struct wl_resource *resource)
+{
+       wl_resource_destroy(resource);
+}
+
+static void
+linux_dmabuf_create_params(struct wl_client *client,
+                          struct wl_resource *linux_dmabuf_resource,
+                          uint32_t params_id)
+{
+       struct weston_compositor *compositor;
+       struct linux_dmabuf_buffer *buffer;
+       uint32_t version;
+       int i;
+
+       version = wl_resource_get_version(linux_dmabuf_resource);
+       compositor = wl_resource_get_user_data(linux_dmabuf_resource);
+
+       buffer = zalloc(sizeof *buffer);
+       if (!buffer)
+               goto err_out;
+
+       for (i = 0; i < MAX_DMABUF_PLANES; i++)
+               buffer->dmabuf_fd[i] = -1;
+
+       buffer->compositor = compositor;
+       buffer->params_resource =
+               wl_resource_create(client,
+                                  &zlinux_buffer_params_interface,
+                                  version, params_id);
+       if (!buffer->params_resource)
+               goto err_dealloc;
+
+       wl_resource_set_implementation(buffer->params_resource,
+                                      &zlinux_buffer_params_implementation,
+                                      buffer, destroy_params);
+
+       return;
+
+err_dealloc:
+       free(buffer);
+
+err_out:
+       wl_resource_post_no_memory(linux_dmabuf_resource);
+}
+
+/** Get the linux_dmabuf_buffer from a wl_buffer resource
+ *
+ * If the given wl_buffer resource was created through the linux_dmabuf
+ * protocol interface, returns the linux_dmabuf_buffer object. This can
+ * be used as a type check for a wl_buffer.
+ *
+ * \param resource A wl_buffer resource.
+ * \return The linux_dmabuf_buffer if it exists, or NULL otherwise.
+ */
+WL_EXPORT struct linux_dmabuf_buffer *
+linux_dmabuf_buffer_get(struct wl_resource *resource)
+{
+       struct linux_dmabuf_buffer *buffer;
+
+       if (!resource)
+               return NULL;
+
+       if (!wl_resource_instance_of(resource, &wl_buffer_interface,
+                                    &linux_dmabuf_buffer_implementation))
+               return NULL;
+
+       buffer = wl_resource_get_user_data(resource);
+       assert(buffer);
+       assert(!buffer->params_resource);
+       assert(buffer->buffer_resource == resource);
+
+       return buffer;
+}
+
+/** Set renderer-private data
+ *
+ * Set the user data for the linux_dmabuf_buffer. It is invalid to overwrite
+ * a non-NULL user data with a new non-NULL pointer. This is meant to
+ * protect against renderers fighting over linux_dmabuf_buffer user data
+ * ownership.
+ *
+ * The renderer-private data is usually set from the
+ * weston_renderer::import_dmabuf hook.
+ *
+ * \param buffer The linux_dmabuf_buffer object to set for.
+ * \param data The new renderer-private data pointer.
+ * \param func Destructor function to be called for the renderer-private
+ *             data when the linux_dmabuf_buffer gets destroyed.
+ *
+ * \sa weston_compositor_import_dmabuf
+ */
+WL_EXPORT void
+linux_dmabuf_buffer_set_user_data(struct linux_dmabuf_buffer *buffer,
+                                 void *data,
+                                 dmabuf_user_data_destroy_func func)
+{
+       assert(data == NULL || buffer->user_data == NULL);
+
+       buffer->user_data = data;
+       buffer->user_data_destroy_func = func;
+}
+
+/** Get renderer-private data
+ *
+ * Get the user data from the linux_dmabuf_buffer.
+ *
+ * \param buffer The linux_dmabuf_buffer to query.
+ * \return Renderer-private data pointer.
+ *
+ * \sa linux_dmabuf_buffer_set_user_data
+ */
+WL_EXPORT void *
+linux_dmabuf_buffer_get_user_data(struct linux_dmabuf_buffer *buffer)
+{
+       return buffer->user_data;
+}
+
+static const struct zlinux_dmabuf_interface linux_dmabuf_implementation = {
+       linux_dmabuf_destroy,
+       linux_dmabuf_create_params
+};
+
+static void
+bind_linux_dmabuf(struct wl_client *client,
+                 void *data, uint32_t version, uint32_t id)
+{
+       struct weston_compositor *compositor = data;
+       struct wl_resource *resource;
+
+       resource = wl_resource_create(client, &zlinux_dmabuf_interface,
+                                     version, id);
+       if (resource == NULL) {
+               wl_client_post_no_memory(client);
+               return;
+       }
+
+       wl_resource_set_implementation(resource, &linux_dmabuf_implementation,
+                                      compositor, NULL);
+
+       /* EGL_EXT_image_dma_buf_import does not provide a way to query the
+        * supported pixel formats. */
+       /* XXX: send formats */
+}
+
+/** Advertise linux_dmabuf support
+ *
+ * Calling this initializes the zlinux_dmabuf protocol support, so that
+ * the interface will be advertised to clients. Essentially it creates a
+ * global. Do not call this function multiple times in the compositor's
+ * lifetime. There is no way to deinit explicitly, globals will be reaped
+ * when the wl_display gets destroyed.
+ *
+ * \param compositor The compositor to init for.
+ * \return Zero on success, -1 on failure.
+ */
+WL_EXPORT int
+linux_dmabuf_setup(struct weston_compositor *compositor)
+{
+       if (!wl_global_create(compositor->wl_display,
+                             &zlinux_dmabuf_interface, 1,
+                             compositor, bind_linux_dmabuf))
+               return -1;
+
+       return 0;
+}
+
+/** Resolve an internal compositor error by disconnecting the client.
+ *
+ * This function is used in cases when the dmabuf-based wl_buffer
+ * turns out unusable and there is no fallback path. This is used by
+ * renderers which are the fallback path in the first place.
+ *
+ * It is possible the fault is caused by a compositor bug, the underlying
+ * graphics stack bug or normal behaviour, or perhaps a client mistake.
+ * In any case, the options are to either composite garbage or nothing,
+ * or disconnect the client. This is a helper function for the latter.
+ *
+ * The error is sent as a INVALID_OBJECT error on the client's wl_display.
+ *
+ * \param buffer The linux_dmabuf_buffer that is unusable.
+ * \param msg A custom error message attached to the protocol error.
+ */
+WL_EXPORT void
+linux_dmabuf_buffer_send_server_error(struct linux_dmabuf_buffer *buffer,
+                                     const char *msg)
+{
+       struct wl_client *client;
+       struct wl_resource *display_resource;
+       uint32_t id;
+
+       assert(buffer->buffer_resource);
+       id = wl_resource_get_id(buffer->buffer_resource);
+       client = wl_resource_get_client(buffer->buffer_resource);
+       display_resource = wl_client_get_object(client, 1);
+
+       assert(display_resource);
+       wl_resource_post_error(display_resource,
+                              WL_DISPLAY_ERROR_INVALID_OBJECT,
+                              "linux_dmabuf server error with "
+                              "wl_buffer@%u: %s", id, msg);
+}
diff --git a/src/linux-dmabuf.h b/src/linux-dmabuf.h
new file mode 100644 (file)
index 0000000..162ff58
--- /dev/null
@@ -0,0 +1,84 @@
+/*
+ * Copyright © 2014, 2015 Collabora, Ltd.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and
+ * its documentation for any purpose is hereby granted without fee, provided
+ * that the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of the copyright holders not be used in
+ * advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission.  The copyright holders make
+ * no representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
+ * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef WESTON_LINUX_DMABUF_H
+#define WESTON_LINUX_DMABUF_H
+
+#include <stdint.h>
+
+#define MAX_DMABUF_PLANES 4
+
+struct linux_dmabuf_buffer;
+typedef void (*dmabuf_user_data_destroy_func)(
+                       struct linux_dmabuf_buffer *buffer);
+
+struct linux_dmabuf_buffer {
+       struct wl_resource *buffer_resource;
+       struct wl_resource *params_resource;
+       struct weston_compositor *compositor;
+       int32_t width;
+       int32_t height;
+       uint32_t format;
+       uint32_t flags; /* enum zlinux_buffer_params_flags */
+       int n_planes;
+       int dmabuf_fd[MAX_DMABUF_PLANES];
+       uint32_t offset[MAX_DMABUF_PLANES];
+       uint32_t stride[MAX_DMABUF_PLANES];
+       uint64_t modifier[MAX_DMABUF_PLANES];
+
+       void *user_data;
+       dmabuf_user_data_destroy_func user_data_destroy_func;
+
+       /* XXX:
+        *
+        * Add backend private data. This would be for the backend
+        * to do all additional imports it might ever use in advance.
+        * The basic principle, even if not implemented in drivers today,
+        * is that dmabufs are first attached, but the actual allocation
+        * is deferred to first use. This would allow the exporter and all
+        * attachers to agree on how to allocate.
+        *
+        * The DRM backend would use this to create drmFBs for each
+        * dmabuf_buffer, just in case at some point it would become
+        * feasible to scan it out directly. This would improve the
+        * possibilities to successfully scan out, avoiding compositing.
+        */
+};
+
+int
+linux_dmabuf_setup(struct weston_compositor *compositor);
+
+struct linux_dmabuf_buffer *
+linux_dmabuf_buffer_get(struct wl_resource *resource);
+
+void
+linux_dmabuf_buffer_set_user_data(struct linux_dmabuf_buffer *buffer,
+                                 void *data,
+                                 dmabuf_user_data_destroy_func func);
+void *
+linux_dmabuf_buffer_get_user_data(struct linux_dmabuf_buffer *buffer);
+
+void
+linux_dmabuf_buffer_send_server_error(struct linux_dmabuf_buffer *buffer,
+                                     const char *msg);
+
+#endif /* WESTON_LINUX_DMABUF_H */