This is a note to let you know that I've just added the patch titled
drm/amd/display: fix overflow on MIN_I64 definition
to the 6.0-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-amd-display-fix-overflow-on-min_i64-definition.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 77ef1f27ce6143fc6e4c353cd3f857a3030be1bd
Author: David Gow <davidgow@xxxxxxxxxx>
Date: Thu Aug 11 17:43:26 2022 -0300
drm/amd/display: fix overflow on MIN_I64 definition
[ Upstream commit 6ae0632d17759852c07e2d1e0a31c728eb6ba246 ]
The definition of MIN_I64 in bw_fixed.c can cause gcc to whinge about
integer overflow, because it is treated as a positive value, which is
then negated. The temporary positive value is not necessarily
representable.
This causes the following warning:
../drivers/gpu/drm/amd/amdgpu/../display/dc/dml/calcs/bw_fixed.c:30:19:
warning: integer overflow in expression ‘-9223372036854775808’ of type
‘long long int’ results in ‘-9223372036854775808’ [-Woverflow]
30 | (int64_t)(-(1LL << 63))
| ^
Writing out (-MAX_I64 - 1) works instead.
Signed-off-by: David Gow <davidgow@xxxxxxxxxx>
Signed-off-by: Tales Aparecida <tales.aparecida@xxxxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/amd/display/dc/dml/calcs/bw_fixed.c b/drivers/gpu/drm/amd/display/dc/dml/calcs/bw_fixed.c
index 6ca288fb5fb9..2d46bc527b21 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/calcs/bw_fixed.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/calcs/bw_fixed.c
@@ -26,12 +26,12 @@
#include "bw_fixed.h"
-#define MIN_I64 \
- (int64_t)(-(1LL << 63))
-
#define MAX_I64 \
(int64_t)((1ULL << 63) - 1)
+#define MIN_I64 \
+ (-MAX_I64 - 1)
+
#define FRACTIONAL_PART_MASK \
((1ULL << BW_FIXED_BITS_PER_FRACTIONAL_PART) - 1)
