Subject: Re: linux-next: build failure after merge of the header_cleanup tree

From: Stephen Rothwell <[email-masked]>
Date: Tue, 19 Dec 2023 14:57:34 +1100

Hi all,

On Mon, 18 Dec 2023 17:40:30 +1100 Stephen Rothwell <[email-masked]> wrote:
>
> After merging the header_cleanup tree, today's linux-next build (arm
> multi_v7_defconfig) failed like this:
> 
> In file included from include/linux/kernel.h:27,
>                  from drivers/gpu/ipu-v3/ipu-dp.c:7:
> include/drm/drm_color_mgmt.h: In function 'drm_color_lut_extract':
> include/drm/drm_color_mgmt.h:45:46: error: implicit declaration of function 'mul_u32_u32' [-Werror=implicit-function-declaration]
>    45 |                 return DIV_ROUND_CLOSEST_ULL(mul_u32_u32(user_input, (1 << bit_precision) - 1),
>       |                                              ^~~~~~~~~~~
> include/linux/math.h:104:36: note: in definition of macro 'DIV_ROUND_CLOSEST_ULL'
>   104 |         unsigned long long _tmp = (x) + (__d) / 2;      \
>       |                                    ^
> In file included from include/linux/time.h:6,
>                  from include/linux/videodev2.h:59,
>                  from include/video/imx-ipu-v3.h:16,
>                  from drivers/gpu/ipu-v3/ipu-dp.c:14:
> include/linux/math64.h: At top level:
> include/linux/math64.h:155:19: error: conflicting types for 'mul_u32_u32'; have 'u64(u32,  u32)' {aka 'long long unsigned int(unsigned int,  unsigned int)'}
>   155 | static inline u64 mul_u32_u32(u32 a, u32 b)
>       |                   ^~~~~~~~~~~
> include/drm/drm_color_mgmt.h:45:46: note: previous implicit declaration of 'mul_u32_u32' with type 'int()'
>    45 |                 return DIV_ROUND_CLOSEST_ULL(mul_u32_u32(user_input, (1 << bit_precision) - 1),
>       |                                              ^~~~~~~~~~~
> include/linux/math.h:104:36: note: in definition of macro 'DIV_ROUND_CLOSEST_ULL'
>   104 |         unsigned long long _tmp = (x) + (__d) / 2;      \
>       |                                    ^
> cc1: some warnings being treated as errors
> In file included from include/linux/kernel.h:27,
>                  from drivers/gpu/drm/omapdrm/dss/dispc_coefs.c:7:
> include/drm/drm_color_mgmt.h: In function 'drm_color_lut_extract':
> include/drm/drm_color_mgmt.h:45:46: error: implicit declaration of function 'mul_u32_u32' [-Werror=implicit-function-declaration]
>    45 |                 return DIV_ROUND_CLOSEST_ULL(mul_u32_u32(user_input, (1 << bit_precision) - 1),
>       |                                              ^~~~~~~~~~~
> include/linux/math.h:104:36: note: in definition of macro 'DIV_ROUND_CLOSEST_ULL'
>   104 |         unsigned long long _tmp = (x) + (__d) / 2;      \
>       |                                    ^
> In file included from include/linux/jiffies.h:7,
>                  from include/linux/ktime.h:25,
>                  from include/linux/timer.h:6,
>                  from include/linux/workqueue.h:9,
>                  from include/linux/mm_types.h:19,
>                  from include/linux/mmzone.h:22,
>                  from include/linux/gfp.h:7,
>                  from include/linux/stackdepot.h:25,
>                  from include/drm/drm_modeset_lock.h:28,
>                  from include/drm/drm_crtc.h:30,
>                  from drivers/gpu/drm/omapdrm/dss/omapdss.h:11,
>                  from drivers/gpu/drm/omapdrm/dss/dispc_coefs.c:9:
> include/linux/math64.h: At top level:
> include/linux/math64.h:155:19: error: conflicting types for 'mul_u32_u32'; have 'u64(u32,  u32)' {aka 'long long unsigned int(unsigned int,  unsigned int)'}
>   155 | static inline u64 mul_u32_u32(u32 a, u32 b)
>       |                   ^~~~~~~~~~~
> include/drm/drm_color_mgmt.h:45:46: note: previous implicit declaration of 'mul_u32_u32' with type 'int()'
>    45 |                 return DIV_ROUND_CLOSEST_ULL(mul_u32_u32(user_input, (1 << bit_precision) - 1),
>       |                                              ^~~~~~~~~~~
> include/linux/math.h:104:36: note: in definition of macro 'DIV_ROUND_CLOSEST_ULL'
>   104 |         unsigned long long _tmp = (x) + (__d) / 2;      \
>       |                                    ^
> cc1: some warnings being treated as errors

This turns out to be a semantic conflict (or exposing a bug in commit

 c6fbb6bca108 ("drm: Fix color LUT rounding")

from the drm tree.

I have applied the following merge fix up patch (which should probably
be applied to the drm tree, if possible).

From: Stephen Rothwell <[email-masked]>
Date: Tue, 19 Dec 2023 14:43:41 +1100
Subject: [PATCH] drm: using mul_u32_u32() requires linux/math64.h

Some pending include file cleanups produced this error:

In file included from include/linux/kernel.h:27,
                 from drivers/gpu/ipu-v3/ipu-dp.c:7:
include/drm/drm_color_mgmt.h: In function 'drm_color_lut_extract':
include/drm/drm_color_mgmt.h:45:46: error: implicit declaration of function 'mul_u32_u32' [-Werror=implicit-function-declaration]
   45 |                 return DIV_ROUND_CLOSEST_ULL(mul_u32_u32(user_input, (1 << bit_precision) - 1),
      |                                              ^~~~~~~~~~~

Signed-off-by: Stephen Rothwell <[email-masked]>
---
 include/drm/drm_color_mgmt.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/drm/drm_color_mgmt.h b/include/drm/drm_color_mgmt.h
index 54b2b2467bfd..ed81741036d7 100644
--- a/include/drm/drm_color_mgmt.h
+++ b/include/drm/drm_color_mgmt.h
@@ -24,6 +24,7 @@
 #define __DRM_COLOR_MGMT_H__
 
 #include <linux/ctype.h>
+#include <linux/math64.h>
 #include <drm/drm_property.h>
 
 struct drm_crtc;
-- 
2.40.1

-- 
Cheers,
Stephen Rothwell