[Mesa-dev] [PATCH v2] dri3: For 1.2, use root window instead of pixmap drawable

[Olivier Fourdan]

get_supported_modifiers() and pixmap_from_buffers() requests both
expect a window as drawable, passing a pixmap will fail as the Xserver
will fail to match the given drawable to a window.

That leads to dri3_alloc_render_buffer() to return NULL and breaks
rendering when using GLX_DOUBLEBUFFER on pixmaps.

Query the root window of the pixmap on first init, and use the root
window instead of the pixmap drawable for get_supported_modifiers()
and pixmap_from_buffers().

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107117
Fixes: 069fdd5 ("egl/x11: Support DRI3 v1.1")
Signed-off-by: Olivier Fourdan <ofourdan at redhat.com>
---
 v2: Use the root window instead of reverting to pixmap_from_buffer()
     as suggested by Eric.

 src/loader/loader_dri3_helper.c | 31 +++++++++++++++++++++++++++++--
 src/loader/loader_dri3_helper.h |  1 +
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/src/loader/loader_dri3_helper.c b/src/loader/loader_dri3_helper.c
index f0ff2f07bd..c7ad67cd04 100644
--- a/src/loader/loader_dri3_helper.c
+++ b/src/loader/loader_dri3_helper.c
@@ -1091,6 +1091,21 @@ has_supported_modifier(struct loader_dri3_drawable *draw, unsigned int format,
    free(supported_modifiers);
    return found;
 }
+
+static xcb_window_t
+get_root_window (struct loader_dri3_drawable *draw)
+{
+   xcb_get_geometry_cookie_t cookie;
+   xcb_get_geometry_reply_t *reply;
+   xcb_window_t window = draw->drawable;
+
+   cookie = xcb_get_geometry(draw->conn, draw->drawable);
+   if ((reply = xcb_get_geometry_reply(draw->conn, cookie, NULL)))
+      window = reply->root;
+   free(reply);
+
+   return window;
+}
 #endif
 
 /** loader_dri3_alloc_render_buffer
@@ -1149,7 +1164,7 @@ dri3_alloc_render_buffer(struct loader_dri3_drawable *draw, unsigned int format,
          uint32_t count = 0;
 
          mod_cookie = xcb_dri3_get_supported_modifiers(draw->conn,
-                                                       draw->drawable,
+                                                       draw->window,
                                                        depth, buffer->cpp * 8);
          mod_reply = xcb_dri3_get_supported_modifiers_reply(draw->conn,
                                                             mod_cookie,
@@ -1281,7 +1296,7 @@ dri3_alloc_render_buffer(struct loader_dri3_drawable *draw, unsigned int format,
        buffer->modifier != DRM_FORMAT_MOD_INVALID) {
       xcb_dri3_pixmap_from_buffers(draw->conn,
                                    pixmap,
-                                   draw->drawable,
+                                   draw->window,
                                    num_planes,
                                    width, height,
                                    buffer->strides[0], buffer->offsets[0],
@@ -1432,7 +1447,19 @@ dri3_update_drawable(__DRIdrawable *driDrawable,
          xcb_unregister_for_special_event(draw->conn, draw->special_event);
          draw->special_event = NULL;
       }
+
+#ifdef HAVE_DRI3_MODIFIERS
+      /* get_supported_modifiers() and pixmap_from_buffers() expect a window,
+       * not just a drawable, and will fail if we pass the pixmap drawable.
+       * So, in case of a pixmap, use the root window instead.
+       */
+      if (draw->is_pixmap)
+         draw->window = get_root_window(draw);
+      else
+#endif
+         draw->window = draw->drawable;
    }
+
    dri3_flush_present_events(draw);
    mtx_unlock(&draw->mtx);
    return true;
diff --git a/src/loader/loader_dri3_helper.h b/src/loader/loader_dri3_helper.h
index 7e3d82947b..51d000343d 100644
--- a/src/loader/loader_dri3_helper.h
+++ b/src/loader/loader_dri3_helper.h
@@ -114,6 +114,7 @@ struct loader_dri3_drawable {
    xcb_connection_t *conn;
    __DRIdrawable *dri_drawable;
    xcb_drawable_t drawable;
+   xcb_window_t window;
    int width;
    int height;
    int depth;
-- 
2.17.1