This implementations bypasses gbm and passes the dmabuf handles directly
to libdrm for composition.

Signed-off-by: Tomohito Esaki <[email protected]>
---
 libweston/compositor-drm.c | 125 ++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 107 insertions(+), 18 deletions(-)

diff --git a/libweston/compositor-drm.c b/libweston/compositor-drm.c
index a707fc4..b15fa01 100644
--- a/libweston/compositor-drm.c
+++ b/libweston/compositor-drm.c
@@ -151,6 +151,9 @@ struct drm_fb {
 
        /* Used by dumb fbs */
        void *map;
+
+       /* Used by dmabuf */
+       bool is_dmabuf;
 };
 
 struct drm_edid {
@@ -389,6 +392,76 @@ drm_fb_destroy_dumb(struct drm_fb *fb)
        drmIoctl(fd, DRM_IOCTL_MODE_DESTROY_DUMB, &destroy_arg);
 }
 
+static inline void
+close_drm_handle(int fd, uint32_t handle)
+{
+       struct drm_gem_close gem_close = { .handle = handle };
+       int ret;
+
+       ret = drmIoctl(fd, DRM_IOCTL_GEM_CLOSE, &gem_close);
+       if (ret)
+               weston_log("DRM_IOCTL_GEM_CLOSE failed.(%s)\n",
+                          strerror(errno));
+}
+
+static struct drm_fb *
+drm_fb_create_dmabuf(struct linux_dmabuf_buffer *dmabuf,
+                    struct drm_backend *backend, uint32_t format)
+{
+       struct drm_fb *fb = NULL;
+       uint32_t width, height, fb_id, handles[4] = {0};
+       int i, ret;
+
+       if (!format)
+               return NULL;
+
+       width = dmabuf->attributes.width;
+       height = dmabuf->attributes.height;
+       if (backend->min_width > width ||
+           width > backend->max_width ||
+           backend->min_height > height ||
+           height > backend->max_height)
+               return NULL;
+
+       for (i = 0; i < dmabuf->attributes.n_planes; i++) {
+               ret = drmPrimeFDToHandle(backend->drm.fd,
+                                        dmabuf->attributes.fd[i],
+                                        &handles[i]);
+               if (ret)
+                       goto done;
+       }
+
+       ret = drmModeAddFB2(backend->drm.fd, width, height,
+                           format, handles, dmabuf->attributes.stride,
+                           dmabuf->attributes.offset, &fb_id, 0);
+       if (ret)
+               goto done;
+
+       fb = zalloc(sizeof *fb);
+       if (!fb)
+           goto done;
+
+       fb->fb_id = fb_id;
+       fb->stride = dmabuf->attributes.stride[0];
+       fb->fd = backend->drm.fd;
+       fb->is_dmabuf = true;
+
+done:
+       for (i = 0; i < dmabuf->attributes.n_planes; i++) {
+               if (!handles[i])
+                       continue;
+               close_drm_handle(backend->drm.fd, handles[i]);
+       }
+
+       return fb;
+}
+
+static void
+drm_fb_destroy_dmabuf(struct drm_fb *fb)
+{
+       drm_fb_destroy(fb, fb->fd);
+}
+
 static struct drm_fb *
 drm_fb_get_from_bo(struct gbm_bo *bo,
                   struct drm_backend *backend, uint32_t format)
@@ -475,6 +548,8 @@ drm_output_release_fb(struct drm_output *output, struct 
drm_fb *fb)
        if (fb->map &&
             (fb != output->dumb[0] && fb != output->dumb[1])) {
                drm_fb_destroy_dumb(fb);
+       } else if (fb->is_dmabuf) {
+               drm_fb_destroy_dmabuf(fb);
        } else if (fb->bo) {
                if (fb->is_client_buffer)
                        gbm_bo_destroy(fb->bo);
@@ -486,12 +561,12 @@ drm_output_release_fb(struct drm_output *output, struct 
drm_fb *fb)
 
 static uint32_t
 drm_output_check_scanout_format(struct drm_output *output,
-                               struct weston_surface *es, struct gbm_bo *bo)
+                               struct weston_surface *es, uint32_t format)
 {
-       uint32_t format;
        pixman_region32_t r;
 
-       format = gbm_bo_get_format(bo);
+       /* We relay on the GBM format enum and DRM format enum to be
+          identical */
 
        if (format == GBM_FORMAT_ARGB8888) {
                /* We can scanout an ARGB buffer if the surface's
@@ -521,12 +596,13 @@ drm_output_prepare_scanout_view(struct drm_output *output,
        struct drm_backend *b = to_drm_backend(output->base.compositor);
        struct weston_buffer *buffer = ev->surface->buffer_ref.buffer;
        struct weston_buffer_viewport *viewport = &ev->surface->buffer_viewport;
-       struct gbm_bo *bo;
+       struct linux_dmabuf_buffer *dmabuf;
+       struct gbm_bo *bo = NULL;
        uint32_t format;
 
        if (ev->geometry.x != output->base.x ||
            ev->geometry.y != output->base.y ||
-           buffer == NULL || b->gbm == NULL ||
+           buffer == NULL ||
            buffer->width != output->base.current_mode->width ||
            buffer->height != output->base.current_mode->height ||
            output->base.transform != viewport->buffer.transform ||
@@ -536,22 +612,35 @@ drm_output_prepare_scanout_view(struct drm_output *output,
        if (ev->geometry.scissor_enabled)
                return NULL;
 
-       bo = gbm_bo_import(b->gbm, GBM_BO_IMPORT_WL_BUFFER,
-                          buffer->resource, GBM_BO_USE_SCANOUT);
+       dmabuf = linux_dmabuf_buffer_get(buffer->resource);
+       if (dmabuf) {
+               format = drm_output_check_scanout_format(
+                       output, ev->surface, dmabuf->attributes.format);
+               if (format == 0)
+                       return NULL;
 
-       /* Unable to use the buffer for scanout */
-       if (!bo)
-               return NULL;
+               output->next = drm_fb_create_dmabuf(dmabuf, b, format);
+               if (!output->next)
+                       return NULL;
+       } else if (b->gbm) {
+               bo = gbm_bo_import(b->gbm, GBM_BO_IMPORT_WL_BUFFER,
+                                  buffer->resource, GBM_BO_USE_SCANOUT);
 
-       format = drm_output_check_scanout_format(output, ev->surface, bo);
-       if (format == 0) {
-               gbm_bo_destroy(bo);
-               return NULL;
-       }
+               /* Unable to use the buffer for scanout */
+               if (!bo)
+                       return NULL;
 
-       output->next = drm_fb_get_from_bo(bo, b, format);
-       if (!output->next) {
-               gbm_bo_destroy(bo);
+               format = drm_output_check_scanout_format(
+                       output, ev->surface, gbm_bo_get_format(bo));
+               if (format == 0)
+                       return NULL;
+
+               output->next = drm_fb_get_from_bo(bo, b, format);
+               if (!output->next) {
+                       gbm_bo_destroy(bo);
+                       return NULL;
+               }
+       } else {
                return NULL;
        }
 
-- 
2.7.4

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