[PATCH v2 07/40] drm: Add a simple generator of random permutations

[Joonas Lahtinen]

On pe, 2016-12-16 at 07:46 +0000, Chris Wilson wrote:
> When testing, we want a random but yet reproducible order in which to
> process elements. Here we create an array which is a random (using the
> Tausworthe PRNG) permutation of the order in which to execute.
> 
> v2: Tidier code by David Herrmann
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: David Herrmann <dh.herrmann at gmail.com>

<SNIP>

> @@ -0,0 +1,41 @@
> +#include <linux/bitops.h>
> +#include <linux/kernel.h>
> +#include <linux/random.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +
> +#include "drm_random.h"
> +
> +static inline u32 prandom_u32_max_state(u32 ep_ro, struct rnd_state *state)
> +{
> +	return upper_32_bits((u64)prandom_u32_state(state) * ep_ro);
> +}
> +

To be submitted upstream. If you prefix the function here, there won't
be a conflict when the upstream part gets merged.

> +++ b/drivers/gpu/drm/lib/drm_random.h
> @@ -0,0 +1,21 @@
> +#ifndef __DRM_RANDOM_H__
> +#define __DRM_RANDOM_H
> +
> +#include <linux/random.h>
> +
> +#define RND_STATE_INITIALIZER(seed__) ({				\
> +	struct rnd_state state__;					\
> +	prandom_seed_state(&state__, (seed__));				\
> +	state__;							\
> +})
> +
> +#define RND_STATE(name__, seed__) \
> +	struct rnd_state name__ = RND_STATE_INITIALIZER(seed__)

For upstream submission too. Same comment as above.

Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation