Change return type from inxed_t to uint32_t for GetFlagValue.

Update doc.

include/ck/utility/work_scheduling.hpp

@@ -65,18 +65,19 @@ class StridedReductionTileLoop
     /// @brief      Calculate this workgroup flag index.
     ///
     /// @note       Note this scheduler intentionaly does not have flag index as its member, since
-    ///             the number of `k_tiles` may change when iterating (ie. in grouped gemm,
-    ///             different groups may have different `k_tiles` in K dimension).
+    ///             current workgroup may process tiles across different MN-output tiles or
+    ///             acorss different GEMMs (grouped gemm).
     ///
-    /// @param[in]  k_tiles               The number of data tiles in the reduced dimension.
-    /// @param[in]  output_tile_idx         The output (MN) tile index (of current GEMM).
-    /// @param[in]  output_tile_idx_offset  The output tile index offset.
+    /// @param[in]  k_tiles                 The number of data tiles in the reduced dimension.
+    /// @param[in]  output_tile_idx         The output (MN) linear tile index (of current GEMM).
+    /// @param[in]  output_tile_idx_offset  The accumulated offset of output tiles from previous
+    ///                                     GEMMs.
     ///
     /// @return     The workgroup flag index.
     ///
-    __device__ index_t GetWorkgroupFlagIdx(index_t k_tiles,
-                                           index_t output_tile_idx,
-                                           index_t output_tile_idx_offset) const
+    __device__ uint32_t GetWorkgroupFlagIdx(index_t k_tiles,
+                                            index_t output_tile_idx,
+                                            index_t output_tile_idx_offset) const
     {
         return (output_tile_idx + output_tile_idx_offset) % GetFlagCount(k_tiles);
     }
@@ -91,8 +92,9 @@ class StridedReductionTileLoop
     __device__ void
     FlagFinished(index_t k_tiles, index_t output_tile_idx, index_t output_tile_idx_offset)
     {
-        finished_block_flags_.inc(
-            GetWorkgroupFlagIdx(k_tiles, output_tile_idx, output_tile_idx_offset));
+        const auto fidx = GetWorkgroupFlagIdx(k_tiles, output_tile_idx, output_tile_idx_offset);
+
+        finished_block_flags_.inc(fidx);
     }
 
     ///
@@ -149,12 +151,12 @@ class StridedReductionTileLoop
     /// @param[in]  output_tile_idx         The output (MN) tile index.
     /// @param[in]  output_tile_idx_offset  The output tile index offset.
     ///
-    __device__ index_t GetFlagValue(index_t k_tiles,
-                                    index_t output_tile_idx,
-                                    index_t output_tile_idx_offset) const
+    __device__ uint32_t GetFlagValue(index_t k_tiles,
+                                     index_t output_tile_idx,
+                                     index_t output_tile_idx_offset) const
     {
-        return static_cast<index_t>(finished_block_flags_.ld(
-            GetWorkgroupFlagIdx(k_tiles, output_tile_idx, output_tile_idx_offset)));
+        return finished_block_flags_.ld(
+            GetWorkgroupFlagIdx(k_tiles, output_tile_idx, output_tile_idx_offset));
     }
 
     const index_t tile_count_;