cogl/renderer: Always try to use GLX_NV_robustness_video_memory_purge

It was always set to TRUE and mutter is the only user.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3887>

cogl/cogl/cogl-context.h

@@ -253,10 +253,6 @@ typedef enum _CoglGraphicsResetStatus
  * extension in which case this will only ever return
  * #COGL_GRAPHICS_RESET_STATUS_NO_ERROR.
  *
- * Applications must explicitly use a backend specific method to
- * request that errors get reported such as X11's
- * cogl_xlib_renderer_request_reset_on_video_memory_purge().
- *
  * Return value: a #CoglGraphicsResetStatus
  */
 COGL_EXPORT CoglGraphicsResetStatus

cogl/cogl/cogl-renderer-private.h

@@ -63,7 +63,6 @@ struct _CoglRenderer
 #ifdef HAVE_X11
   Display *foreign_xdpy;
   gboolean xlib_enable_event_retrieval;
-  gboolean xlib_want_reset_on_video_memory_purge;
 #endif
 
   CoglDriver driver;

cogl/cogl/cogl-renderer.c

@@ -224,16 +224,6 @@ cogl_xlib_renderer_set_foreign_display (CoglRenderer *renderer,
      it will also do its own event retrieval */
   renderer->xlib_enable_event_retrieval = FALSE;
 }
-
-void
-cogl_xlib_renderer_request_reset_on_video_memory_purge (CoglRenderer *renderer,
-                                                        gboolean enable)
-{
-  g_return_if_fail (COGL_IS_RENDERER (renderer));
-  g_return_if_fail (!renderer->connected);
-
-  renderer->xlib_want_reset_on_video_memory_purge = enable;
-}
 #endif /* HAVE_X11 */
 
 gboolean

cogl/cogl/cogl-xlib-renderer.h

@@ -112,45 +112,4 @@ COGL_EXPORT void
 cogl_xlib_renderer_set_foreign_display (CoglRenderer *renderer,
                                         Display *display);
 
-/**
- * cogl_xlib_renderer_request_reset_on_video_memory_purge: (skip)
- * @renderer: a #CoglRenderer
- * @enable: The new value
- *
- * Sets whether Cogl should make use of the
- * NV_robustness_video_memory_purge extension, if exposed by the
- * driver, by initializing the GLX context appropriately.
- *
- * The extension is only useful when running on certain versions of
- * the NVIDIA driver. Quoting from the spec:
- *
- * "The NVIDIA OpenGL driver architecture on Linux has a limitation:
- *  resources located in video memory are not persistent across certain
- *  events. VT switches, suspend/resume events, and mode switching
- *  events may erase the contents of video memory. Any resource that
- *  is located exclusively in video memory, such as framebuffer objects
- *  (FBOs), will be lost."
- *
- * "This extension provides a way for applications to discover when video
- *  memory content has been lost, so that the application can re-populate
- *  the video memory content as necessary."
- *
- * "Any driver that exposes this extension is a driver that considers
- *  video memory to be volatile. Once the driver stack has been
- *  improved, the extension will no longer be exposed."
- *
- * cogl_get_graphics_reset_status() needs to be called at least once
- * every frame to find out if video memory was purged.
- *
- * Note that this doesn't cause Cogl to enable robust buffer access
- * but other context reset errors may still happen and be reported via
- * cogl_get_graphics_reset_status() if external factors cause the
- * driver to trigger them.
- *
- * This defaults to %FALSE and is effective only if called before
- * cogl_display_setup() .
- */
-COGL_EXPORT void
-cogl_xlib_renderer_request_reset_on_video_memory_purge (CoglRenderer *renderer,
-                                                        gboolean enable);
 G_END_DECLS

cogl/cogl/winsys/cogl-winsys-glx.c

@@ -628,8 +628,7 @@ create_gl3_context (CoglDisplay *display,
   /* We can't check the presence of this extension with the usual
      COGL_WINSYS_FEATURE machinery because that only gets initialized
      later when the CoglContext is created. */
-  if (display->renderer->xlib_want_reset_on_video_memory_purge &&
-      strstr (glx_renderer->glXQueryExtensionsString (xlib_renderer->xdpy,
+  if (strstr (glx_renderer->glXQueryExtensionsString (xlib_renderer->xdpy,
                                                       DefaultScreen (xlib_renderer->xdpy)),
               "GLX_NV_robustness_video_memory_purge"))
     {

src/backends/x11/meta-renderer-x11.c

@@ -88,7 +88,6 @@ meta_renderer_x11_create_cogl_renderer (MetaRenderer *renderer)
   cogl_renderer_set_custom_winsys (cogl_renderer, get_x11_cogl_winsys_vtable,
                                    NULL);
   cogl_xlib_renderer_set_foreign_display (cogl_renderer, xdisplay);
-  cogl_xlib_renderer_request_reset_on_video_memory_purge (cogl_renderer, TRUE);
 
   return cogl_renderer;
 }