nv50_gr_chan
struct nv50_gr *gr = nv50_gr_chan(object)->gr;
nv50_gr_chan = {
struct nv50_gr_chan *chan;
nvkm_object_ctor(&nv50_gr_chan, oclass, &chan->object);
#define nv50_gr_chan(p) container_of((p), struct nv50_gr_chan, object)