diff --git a/drivers/gpu/drm/amd/include/cik_structs.h b/drivers/gpu/drm/amd/include/cik_structs.h
index 749eab94e335..699e658c3cec 100644
--- a/drivers/gpu/drm/amd/include/cik_structs.h
+++ b/drivers/gpu/drm/amd/include/cik_structs.h
@@ -282,8 +282,7 @@ struct cik_sdma_rlc_registers {
 	uint32_t reserved_123;
 	uint32_t reserved_124;
 	uint32_t reserved_125;
-	uint32_t reserved_126;
-	uint32_t reserved_127;
+	/* reserved_126,127: repurposed for driver-internal use */
 	uint32_t sdma_engine_id;
 	uint32_t sdma_queue_id;
 };
diff --git a/drivers/gpu/drm/amd/include/v9_structs.h b/drivers/gpu/drm/amd/include/v9_structs.h
index ceaf4932258d..8b383dbe1cda 100644
--- a/drivers/gpu/drm/amd/include/v9_structs.h
+++ b/drivers/gpu/drm/amd/include/v9_structs.h
@@ -151,8 +151,7 @@ struct v9_sdma_mqd {
 	uint32_t reserved_123;
 	uint32_t reserved_124;
 	uint32_t reserved_125;
-	uint32_t reserved_126;
-	uint32_t reserved_127;
+	/* reserved_126,127: repurposed for driver-internal use */
 	uint32_t sdma_engine_id;
 	uint32_t sdma_queue_id;
 };
diff --git a/drivers/gpu/drm/amd/include/vi_structs.h b/drivers/gpu/drm/amd/include/vi_structs.h
index 717fbae1d362..c17613287cd0 100644
--- a/drivers/gpu/drm/amd/include/vi_structs.h
+++ b/drivers/gpu/drm/amd/include/vi_structs.h
@@ -151,8 +151,7 @@ struct vi_sdma_mqd {
 	uint32_t reserved_123;
 	uint32_t reserved_124;
 	uint32_t reserved_125;
-	uint32_t reserved_126;
-	uint32_t reserved_127;
+	/* reserved_126,127: repurposed for driver-internal use */
 	uint32_t sdma_engine_id;
 	uint32_t sdma_queue_id;
 };