This is a note to let you know that I've just added the patch titled
drm: Fix drm_fixp2int_round() making it add 0.5
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-fix-drm_fixp2int_round-making-it-add-0.5.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b529c471c591326e373506bf45b8f1b1d8155e61
Author: Arthur Grillo <arthurgrillo@xxxxxxxxxx>
Date: Sat Mar 16 13:25:20 2024 -0300
drm: Fix drm_fixp2int_round() making it add 0.5
[ Upstream commit 807f96abdf14c80f534c78f2d854c2590963345c ]
As well noted by Pekka[1], the rounding of drm_fixp2int_round is wrong.
To round a number, you need to add 0.5 to the number and floor that,
drm_fixp2int_round() is adding 0.0000076. Make it add 0.5.
[1]: https://lore.kernel.org/all/20240301135327.22efe0dd.pekka.paalanen@xxxxxxxxxxxxx/
Fixes: 8b25320887d7 ("drm: Add fixed-point helper to get rounded integer values")
Suggested-by: Pekka Paalanen <pekka.paalanen@xxxxxxxxxxxxx>
Reviewed-by: Harry Wentland <harry.wentland@xxxxxxx>
Reviewed-by: Melissa Wen <mwen@xxxxxxxxxx>
Signed-off-by: Arthur Grillo <arthurgrillo@xxxxxxxxxx>
Signed-off-by: Melissa Wen <melissa.srw@xxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20240316-drm_fixed-v2-1-c1bc2665b5ed@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h
index 0c9f917a4d4be..81572d32db0c2 100644
--- a/include/drm/drm_fixed.h
+++ b/include/drm/drm_fixed.h
@@ -71,7 +71,6 @@ static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B)
}
#define DRM_FIXED_POINT 32
-#define DRM_FIXED_POINT_HALF 16
#define DRM_FIXED_ONE (1ULL << DRM_FIXED_POINT)
#define DRM_FIXED_DECIMAL_MASK (DRM_FIXED_ONE - 1)
#define DRM_FIXED_DIGITS_MASK (~DRM_FIXED_DECIMAL_MASK)
@@ -90,7 +89,7 @@ static inline int drm_fixp2int(s64 a)
static inline int drm_fixp2int_round(s64 a)
{
- return drm_fixp2int(a + (1 << (DRM_FIXED_POINT_HALF - 1)));
+ return drm_fixp2int(a + DRM_FIXED_ONE / 2);
}
static inline int drm_fixp2int_ceil(s64 a)
