[GRAPH] Match maxChannels for gfx942 CUs (#1302)

[ROCm/rccl commit: 6632183efe]

projects/rccl/src/graph/connect.cc

@@ -804,10 +804,10 @@ ncclResult_t ncclTopoPostset(struct ncclComm* comm, int* firstRanks, int* treePa
     }
   }
 
-  // Only use full MAXCHANNELS for gfx94x and gfx950
-  maxChannels = (IsArchMatch(comm->topo->nodes[GPU].nodes[0].gpu.gcn, "gfx942") || IsArchMatch(comm->topo->nodes[GPU].nodes[0].gpu.gcn, "gfx950")) ?
-    ((comm->topo->nodes[GPU].nodes[0].gpu.cu == 80 || comm->topo->nodes[GPU].nodes[0].gpu.cu == 20 || comm->topo->nodes[GPU].nodes[0].gpu.cu == 38)
-      ? comm->topo->nodes[GPU].nodes[0].gpu.cu : MAXCHANNELS) : 2*CHANNEL_LIMIT;
+  // Only use full MAXCHANNELS for gfx942 (MI300X) and gfx950
+  maxChannels = (IsArchMatch(comm->topo->nodes[GPU].nodes[0].gpu.gcn, "gfx942") ||
+                 IsArchMatch(comm->topo->nodes[GPU].nodes[0].gpu.gcn, "gfx950"))
+                 ? std::min(comm->topo->nodes[GPU].nodes[0].gpu.cu, MAXCHANNELS) : 2*CHANNEL_LIMIT;
 
   if (graphs[NCCL_ALGO_RING]->nIntraChannels > 0 || comm->nNodes > 1) {
     maxChannels = std::min(64, maxChannels);