diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index ea8e6e54672..2d2ff03ed72 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -6148,6 +6148,10 @@ typedef struct nir_lower_subgroups_options {
     */
    nir_instr_filter_cb filter;
 
+   /* In case the exact subgroup size is not known, subgroup_size should be
+    * set to 0. In that case, the maximum subgroup size will be calculated by
+    * ballot_components * ballot_bit_size.
+    */
    uint8_t subgroup_size;
    uint8_t ballot_bit_size;
    uint8_t ballot_components;
diff --git a/src/compiler/nir/nir_lower_subgroups.c b/src/compiler/nir/nir_lower_subgroups.c
index 20b486c2956..896cf11da36 100644
--- a/src/compiler/nir/nir_lower_subgroups.c
+++ b/src/compiler/nir/nir_lower_subgroups.c
@@ -30,6 +30,14 @@
  * \file nir_opt_intrinsics.c
  */
 
+static unsigned
+get_max_subgroup_size(const nir_lower_subgroups_options *options)
+{
+   return options->subgroup_size
+             ? options->subgroup_size
+             : options->ballot_components * options->ballot_bit_size;
+}
+
 static nir_intrinsic_instr *
 lower_subgroups_64bit_split_intrinsic(nir_builder *b, nir_intrinsic_instr *intrin,
                                       unsigned int component)
@@ -494,8 +502,9 @@ lower_boolean_shuffle(nir_builder *b, nir_intrinsic_instr *intrin,
    case nir_intrinsic_rotate: {
       nir_def *delta = nir_as_uniform(b, intrin->src[1].ssa);
       uint32_t cluster_size = nir_intrinsic_cluster_size(intrin);
-      cluster_size = cluster_size ? cluster_size : options->subgroup_size;
-      cluster_size = MIN2(cluster_size, options->subgroup_size);
+      unsigned subgroup_size = get_max_subgroup_size(options);
+      cluster_size = cluster_size ? cluster_size : subgroup_size;
+      cluster_size = MIN2(cluster_size, subgroup_size);
       if (cluster_size == 1) {
          return intrin->src[0].ssa;
       } else if (cluster_size == 2) {
@@ -845,7 +854,7 @@ lower_scan_reduce(nir_builder *b, nir_intrinsic_instr *intrin,
                   const nir_lower_subgroups_options *options)
 {
    const nir_op red_op = nir_intrinsic_reduction_op(intrin);
-   unsigned subgroup_size = options->subgroup_size;
+   unsigned subgroup_size = get_max_subgroup_size(options);
 
    /* Grab the cluster size */
    unsigned cluster_size = subgroup_size;