2023-06-02 10:13:26

by GONG, Ruiqi

Subject: [PATCH] drm/amd/display: fix compilation error due to shifting negative value

Currently compiling linux-next with allmodconfig triggers the following
error:

./drivers/gpu/drm/amd/amdgpu/../display/include/fixed31_32.h: In function ‘dc_fixpt_truncate’:
./drivers/gpu/drm/amd/amdgpu/../display/include/fixed31_32.h:528:22: error: left shift of negative value [-Werror=shift-negative-value]
528 | arg.value &= (~0LL) << (FIXED31_32_BITS_PER_FRACTIONAL_PART - frac_bits);
| ^~

Use `unsigned long long` instead.

Signed-off-by: GONG, Ruiqi <[email protected]>
---
drivers/gpu/drm/amd/display/include/fixed31_32.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/include/fixed31_32.h b/drivers/gpu/drm/amd/display/include/fixed31_32.h
index ece97ae0e826..d4cf7ead1d87 100644
--- a/drivers/gpu/drm/amd/display/include/fixed31_32.h
+++ b/drivers/gpu/drm/amd/display/include/fixed31_32.h
@@ -525,7 +525,7 @@ static inline struct fixed31_32 dc_fixpt_truncate(struct fixed31_32 arg, unsigne

if (negative)
arg.value = -arg.value;
- arg.value &= (~0LL) << (FIXED31_32_BITS_PER_FRACTIONAL_PART - frac_bits);
+ arg.value &= (~0ULL) << (FIXED31_32_BITS_PER_FRACTIONAL_PART - frac_bits);
if (negative)
arg.value = -arg.value;
return arg;
--
2.25.1

2023-06-02 14:42:27

by Hamza Mahfooz

Subject: Re: [PATCH] drm/amd/display: fix compilation error due to shifting negative value

On 6/2/23 06:12, GONG, Ruiqi wrote:
> Currently compiling linux-next with allmodconfig triggers the following
> error:
>
> ./drivers/gpu/drm/amd/amdgpu/../display/include/fixed31_32.h: In function ‘dc_fixpt_truncate’:
> ./drivers/gpu/drm/amd/amdgpu/../display/include/fixed31_32.h:528:22: error: left shift of negative value [-Werror=shift-negative-value]
> 528 | arg.value &= (~0LL) << (FIXED31_32_BITS_PER_FRACTIONAL_PART - frac_bits);
> | ^~
>
> Use `unsigned long long` instead.
>
> Signed-off-by: GONG, Ruiqi <[email protected]>

Applied, thanks!

> ---
> drivers/gpu/drm/amd/display/include/fixed31_32.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/include/fixed31_32.h b/drivers/gpu/drm/amd/display/include/fixed31_32.h
> index ece97ae0e826..d4cf7ead1d87 100644
> --- a/drivers/gpu/drm/amd/display/include/fixed31_32.h
> +++ b/drivers/gpu/drm/amd/display/include/fixed31_32.h
> @@ -525,7 +525,7 @@ static inline struct fixed31_32 dc_fixpt_truncate(struct fixed31_32 arg, unsigne
>
> if (negative)
> arg.value = -arg.value;
> - arg.value &= (~0LL) << (FIXED31_32_BITS_PER_FRACTIONAL_PART - frac_bits);
> + arg.value &= (~0ULL) << (FIXED31_32_BITS_PER_FRACTIONAL_PART - frac_bits);
> if (negative)
> arg.value = -arg.value;
> return arg;
--
Hamza