From: Chris Wilson Date: Wed, 13 Sep 2017 10:51:54 +0000 (+0100) Subject: drm/i915/selftests: Use mul_u32_u32() for 32b x 32b -> 64b result X-Git-Tag: v4.15-rc1~90^2~40^2~104 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=7ce5b6850b47824a2b8d0a17b5fe75f9942e5cd1;p=linux.git drm/i915/selftests: Use mul_u32_u32() for 32b x 32b -> 64b result As realised by commit 9e3d6223d209 ("math64, timers: Fix 32bit mul_u64_u32_shr() and friends"), GCC does not always generate ideal code for performing a 32b x 32b multiply returning a 64b result (i.e. where we idiomatically use u64 result = (u64)x * (u32)x). Signed-off-by: Chris Wilson Link: https://patchwork.freedesktop.org/patch/msgid/20170913105154.2910-2-chris@chris-wilson.co.uk Reviewed-by: Ville Syrjälä --- diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_timeline.c b/drivers/gpu/drm/i915/selftests/i915_gem_timeline.c index 7a44dab631b8..4795877abe56 100644 --- a/drivers/gpu/drm/i915/selftests/i915_gem_timeline.c +++ b/drivers/gpu/drm/i915/selftests/i915_gem_timeline.c @@ -121,7 +121,7 @@ static int igt_sync(void *arg) static unsigned int random_engine(struct rnd_state *rnd) { - return ((u64)prandom_u32_state(rnd) * I915_NUM_ENGINES) >> 32; + return i915_prandom_u32_max_state(I915_NUM_ENGINES, rnd); } static int bench_sync(void *arg) diff --git a/drivers/gpu/drm/i915/selftests/i915_random.c b/drivers/gpu/drm/i915/selftests/i915_random.c index d044bf9a6feb..ea0f5dbc0eb7 100644 --- a/drivers/gpu/drm/i915/selftests/i915_random.c +++ b/drivers/gpu/drm/i915/selftests/i915_random.c @@ -41,11 +41,6 @@ u64 i915_prandom_u64_state(struct rnd_state *rnd) return x; } -static inline u32 i915_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state) -{ - return upper_32_bits((u64)prandom_u32_state(state) * ep_ro); -} - void i915_random_reorder(unsigned int *order, unsigned int count, struct rnd_state *state) { diff --git a/drivers/gpu/drm/i915/selftests/i915_random.h b/drivers/gpu/drm/i915/selftests/i915_random.h index 6c9379871384..7dffedc501ca 100644 --- a/drivers/gpu/drm/i915/selftests/i915_random.h +++ b/drivers/gpu/drm/i915/selftests/i915_random.h @@ -43,6 +43,11 @@ u64 i915_prandom_u64_state(struct rnd_state *rnd); +static inline u32 i915_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state) +{ + return upper_32_bits(mul_u32_u32(prandom_u32_state(state), ep_ro)); +} + unsigned int *i915_random_order(unsigned int count, struct rnd_state *state); void i915_random_reorder(unsigned int *order,