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Commit 7ce5b685 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/selftests: Use mul_u32_u32() for 32b x 32b -> 64b result 



As realised by commit 9e3d6223 ("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: default avatarChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20170913105154.2910-2-chris@chris-wilson.co.uk


Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
parent 3123698f

drivers/gpu/drm/i915/selftests/i915_gem_timeline.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -121,7 +121,7 @@ static int igt_sync(void *arg) 




static unsigned int random_engine(struct rnd_state *rnd)

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)

static int bench_sync(void *arg)

drivers/gpu/drm/i915/selftests/i915_random.c

+0 −5
Original line number Original line Diff line number Diff line
@@ -41,11 +41,6 @@ u64 i915_prandom_u64_state(struct rnd_state *rnd) 
	return x;

	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,

void i915_random_reorder(unsigned int *order, unsigned int count,

			 struct rnd_state *state)

			 struct rnd_state *state)

{

{

drivers/gpu/drm/i915/selftests/i915_random.h

+5 −0
Original line number Original line Diff line number Diff line
@@ -43,6 +43,11 @@ 




u64 i915_prandom_u64_state(struct rnd_state *rnd);

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,

unsigned int *i915_random_order(unsigned int count,

				struct rnd_state *state);

				struct rnd_state *state);

void i915_random_reorder(unsigned int *order,

void i915_random_reorder(unsigned int *order,