Lifetime rules seem to be solid around ->import_attach. So this patch just properly documents them.
Note that pointing directly at the attachment might have issues for devices that have multiple struct device *dev parts constituting the logical gpu and so might need multiple attachment points. Similarly for drm devices which don't need a dma attachment at all (like udl).
But fixing that up is material for different patches.
Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch --- include/drm/drmP.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/include/drm/drmP.h b/include/drm/drmP.h index cd57646..baf030c 100644 --- a/include/drm/drmP.h +++ b/include/drm/drmP.h @@ -681,7 +681,16 @@ struct drm_gem_object { /* dma buf exported from this GEM object */ struct dma_buf *export_dma_buf;
- /* dma buf attachment backing this object */ + /** + * import_attach - dma buf attachment backing this object + * + * Any foreign dma_buf imported as a gem object has this set to the + * attachment point for the device. This is invariant over the lifetime + * of a gem object. + * + * The driver's ->gem_free_object callback is responsible for cleaning + * up the dma_buf attachment and references acquired at import time. + */ struct dma_buf_attachment *import_attach; };