gallium: add pipe_screen::resource_changed

Add a hook to tell drivers that an imported resource may have changed
and they need to update their internal derived resources.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

src/gallium/docs/source/screen.rst

@@ -707,6 +707,20 @@ which isn't multisampled.
 
 
 
+resource_changed
+^^^^^^^^^^^^^^^^
+
+Mark a resource as changed so derived internal resources will be recreated
+on next use.
+
+When importing external images that can't be directly used as texture sampler
+source, internal copies may have to be created that the hardware can sample
+from. When those resources are reimported, the image data may have changed, and
+the previously derived internal resources must be invalidated to avoid sampling
+from old copies.
+
+
+
 resource_destroy
 ^^^^^^^^^^^^^^^^
 

src/gallium/include/pipe/p_screen.h

@@ -224,6 +224,14 @@ struct pipe_screen {
 				  struct winsys_handle *handle,
 				  unsigned usage);
 
+   /**
+    * Mark the resource as changed so derived internal resources will be
+    * recreated on next use.
+    *
+    * This is necessary when reimporting external images that can't be directly
+    * used as texture sampler source, to avoid sampling from old copies.
+    */
+   void (*resource_changed)(struct pipe_screen *, struct pipe_resource *pt);
 
    void (*resource_destroy)(struct pipe_screen *,
 			    struct pipe_resource *pt);