winsys/radeon: allow mapping a user buffer

OpenGL requires this.

Reviewed-by: Christian König <christian.koenig@amd.com>

src/gallium/winsys/radeon/drm/radeon_drm_bo.c

@@ -345,6 +345,10 @@ void *radeon_bo_do_map(struct radeon_bo *bo)
     struct drm_radeon_gem_mmap args = {0};
     void *ptr;
 
+    /* If the buffer is created from user memory, return the user pointer. */
+    if (bo->user_ptr)
+        return bo->user_ptr;
+
     /* Return the pointer if it's already mapped. */
     if (bo->ptr)
         return bo->ptr;
@@ -900,6 +904,7 @@ static struct pb_buffer *radeon_winsys_bo_from_ptr(struct radeon_winsys *rws,
     bo->base.vtbl = &radeon_bo_vtbl;
     bo->mgr = mgr;
     bo->rws = mgr->rws;
+    bo->user_ptr = pointer;
     bo->va = 0;
     bo->initial_domain = RADEON_DOMAIN_GTT;
     pipe_mutex_init(bo->map_mutex);

src/gallium/winsys/radeon/drm/radeon_drm_bo.h

@@ -50,6 +50,7 @@ struct radeon_bo {
 
     struct radeon_bomgr *mgr;
     struct radeon_drm_winsys *rws;
+    void *user_ptr; /* from buffer_from_ptr */
 
     void *ptr;
     pipe_mutex map_mutex;

src/gallium/winsys/radeon/drm/radeon_winsys.h

@@ -394,8 +394,8 @@ struct radeon_winsys {
                                             unsigned *stride);
 
     /**
-     * Get a winsys buffer from a user pointer. The resulting buffer can't be
-     * mapped or exported. Both pointer and size must be page aligned.
+     * Get a winsys buffer from a user pointer. The resulting buffer can't
+     * be exported. Both pointer and size must be page aligned.
      *
      * \param ws        The winsys this function is called from.
      * \param pointer   User pointer to turn into a buffer object.