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* [PATCH] drm/amd/display: use include guards instead of #pragma once in Core 2 headers
@ 2026-11-05 19:23 Jeff Johnson
  2026-11-15  7:38 ` Wayne Lin
  0 siblings, 1 reply; 2+ messages in thread
From: Jeff Johnson @ 2026-11-05 19:23 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter, Fangzhi Zuo,
	Jun Lei, Cheng, Tony
  Cc: amd-gfx, dri-devel, Jeff Johnson

Commit 9d1a737c3c82 ("drm/amd/display: Keep public DC lifecycle APIs
stable beside Core 2") added four headers that use #pragma once, the
only headers in drivers/gpu/drm/amd/display/ to do so; every other
header in the subsystem uses #ifndef include guards.

dc_core_interface.h is included more than once within a single
translation unit (via dc.h and again via api_shim.h / dc_core2.h). In
the amdgpu build all display include paths are spelled with a
"-I.../amdgpu/../display/..." prefix, so the header is reached through
two paths that differ only by a ".." component.

gcc canonicalizes the ".." and deduplicates the header by its real
path, so the normal CC build is fine. sparse (make C=1/C=2) does not
canonicalize ".." for #pragma once, treats the two spellings as
different files and processes the header twice, which breaks the build:

  dc_core_interface.h:14: error: redefinition of \
      unsigned int enum dc2_selection

This fails the CHECK pass for api_shim.c, dc_core2.c and core/dc.c.

Convert the four new headers to standard #ifndef include guards, which
sparse honors regardless of how the path is spelled, matching the rest
of the subsystem. No functional change for gcc builds.

Fixes: 9d1a737c3c82 ("drm/amd/display: Keep public DC lifecycle APIs stable beside Core 2")
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>
---
Issue debugged and patch generated using Claude Code Opus 4.8.
I have reviewed the patch and have verified a clean W=1 C=1 build.
---
 drivers/gpu/drm/amd/display/dc/core2/dc_core2.h           | 5 ++++-
 drivers/gpu/drm/amd/display/dc/core2/dc_core2_init.h      | 5 ++++-
 drivers/gpu/drm/amd/display/dc/dc_api_dispatch/api_shim.h | 5 ++++-
 drivers/gpu/drm/amd/display/dc/inc/dc_core_interface.h    | 5 ++++-
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core2/dc_core2.h b/drivers/gpu/drm/amd/display/dc/core2/dc_core2.h
index a761e85a9973..867fe9023fc7 100644
--- a/drivers/gpu/drm/amd/display/dc/core2/dc_core2.h
+++ b/drivers/gpu/drm/amd/display/dc/core2/dc_core2.h
@@ -3,7 +3,8 @@
  * Copyright 2026 Advanced Micro Devices, Inc.
  */
 
-#pragma once
+#ifndef DC_CORE2_H_
+#define DC_CORE2_H_
 
 #include "inc/dc_core_interface.h"
 
@@ -17,3 +18,5 @@ struct dc_core2 {
 const struct dc2_funcs *core2_funcs(void);
 void core2_construct(struct dc *dc);
 void core2_destruct(struct dc *dc);
+
+#endif /* DC_CORE2_H_ */
diff --git a/drivers/gpu/drm/amd/display/dc/core2/dc_core2_init.h b/drivers/gpu/drm/amd/display/dc/core2/dc_core2_init.h
index a4fa0365cd4f..b081801f664e 100644
--- a/drivers/gpu/drm/amd/display/dc/core2/dc_core2_init.h
+++ b/drivers/gpu/drm/amd/display/dc/core2/dc_core2_init.h
@@ -3,8 +3,11 @@
  * Copyright 2026 Advanced Micro Devices, Inc.
  */
 
-#pragma once
+#ifndef DC_CORE2_INIT_H_
+#define DC_CORE2_INIT_H_
 
 struct dc;
 
 void core2_hardware_init(struct dc *dc);
+
+#endif /* DC_CORE2_INIT_H_ */
diff --git a/drivers/gpu/drm/amd/display/dc/dc_api_dispatch/api_shim.h b/drivers/gpu/drm/amd/display/dc/dc_api_dispatch/api_shim.h
index fee03a5dd596..00cf48b14f53 100644
--- a/drivers/gpu/drm/amd/display/dc/dc_api_dispatch/api_shim.h
+++ b/drivers/gpu/drm/amd/display/dc/dc_api_dispatch/api_shim.h
@@ -3,7 +3,8 @@
  * Copyright 2026 Advanced Micro Devices, Inc.
  */
 
-#pragma once
+#ifndef DC_API_DISPATCH_API_SHIM_H_
+#define DC_API_DISPATCH_API_SHIM_H_
 
 #include "dc.h"
 #include "inc/dc_core_interface.h"
@@ -17,3 +18,5 @@ struct dc2 {
 #define TO_DC2(ptr) ((struct dc2 *)(ptr))
 
 void api_shim_construct(struct dc *dc, const struct dc_init_data *init_params);
+
+#endif /* DC_API_DISPATCH_API_SHIM_H_ */
diff --git a/drivers/gpu/drm/amd/display/dc/inc/dc_core_interface.h b/drivers/gpu/drm/amd/display/dc/inc/dc_core_interface.h
index 35a6218c1285..264bd8bf3bc0 100644
--- a/drivers/gpu/drm/amd/display/dc/inc/dc_core_interface.h
+++ b/drivers/gpu/drm/amd/display/dc/inc/dc_core_interface.h
@@ -3,7 +3,8 @@
  * Copyright 2026 Advanced Micro Devices, Inc.
  */
 
-#pragma once
+#ifndef DC_CORE_INTERFACE_H_
+#define DC_CORE_INTERFACE_H_
 
 struct dc;
 
@@ -29,3 +30,5 @@ struct dc2_funcs {
 void legacy_hardware_init(struct dc *dc);
 void legacy_hardware_release(struct dc *dc);
 const struct dc2_funcs *dc2_legacy_funcs(void);
+
+#endif /* DC_CORE_INTERFACE_H_ */

---
base-commit: d7e11a5269dc892cbee8a01dccbdb20bb4f653da
change-id: 20261105-amdgpu-local-fix-908074837d48


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2026-11-05 19:23 [PATCH] drm/amd/display: use include guards instead of #pragma once in Core 2 headers Jeff Johnson
2026-11-15  7:38 ` Wayne Lin

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